Untersuchungen über Morphologie, Entwicklungsgeschichte und systematische Bedeutung des pseudomonomeren Gynoeceums

Floral morphogenesis of Celtis species: implications for breeding system and reduced floral structure

Article

Full-text available

Sep 2021

Premise: Celtis is the most species-rich genus of Cannabaceae, an economically important family. Celtis species have been described as wind-pollinated and andromonoecious. However, the andromonoecy of Celtis has been debated because there are reports of monoclinous flowers with non-opening anthers on short filaments. Our objective was to study the floral morphogenesis of Celtis to establish the breeding system and to better understand the developmental patterns that lead to the formation of reduced flowers in the genus. Methods: Flowers and floral buds of Celtis species were studied using scanning electron microscopy, high-resolution x-ray computed tomography, and light microscopy. Results: All flowers initiate stamens and carpels during early floral development, but either stamens or carpels abort during later stages. Thus, at anthesis, flowers are either functionally pistillate or functionally staminate. In pistillate flowers, stamens abort late and become staminodes with normal-looking anthers. These anthers have no functional endothecium and, in most of the species studied, produce no viable pollen grains. The gynoecium is pseudomonomerous, and its vascularization is similar in the sampled species. In staminate flowers, the gynoecium aborts early resulting in small pistillodes. No vestiges of petals were found. Conclusions: The species studied are monoecious and not andromonoecious as described earlier. The absence of petals, the carpel and stamen abortion, and the pseudomonomerous gynoecium result in the reduced flowers of Celtis species. The use of high-resolution x-ray computed tomography was essential for a more accurate interpretation of ovary vascularization, confirming the pseudomonomerous structure of the gynoecium.

Flower morphogenesis and gametophyte fertility attest to the rare condition of gynomonoecy in Parietaria debilis (Urticaceae)

Article

Full-text available

Aug 2020

Parietaria debilis G. Forst. is gynomonoecious, which is a rare condition in the Urticaceae family and among angiosperms. Apetalous flowers of two different morph types (monoclinous, pistillate) occur in the same inflorescence and are reduced in size and in the number of whorls and of organs per whorl. The objective of this study was to compare the morphogenesis of monoclinous and pistillate flowers to determine whether the monoclinous flowers produce fertile gametophytes, and elucidate the pathways leading to the absence of stamens and to the changes in number of whorls and organs per whorl. Flower buds and flowers (non-fertilized, fertilized) were processed for surface and anatomical studies. Pollen ultrastructure and viability were determined. Inflorescences with fertilized flowers were checked for the presence and location of fruits/viable seeds. The monoclinous flower has four sepals, four stamens, and a uniovulate pseudomonomerous gynoecium. In the pistillate flower, the stamens are absent or, rarely, aborted. No petals are formed. The gynoecium is pseudomonomerous, originated as a central primordium that differentiates into two carpels, but only one develops and houses an ovule. Monoclinous and pistillate flowers produce viable seeds. Thus, our data confirmed that this species is indeed gynomonoecious.

Comparative floral development reveals novel aspects of structure and diversity of flowers in Cannabaceae

Preprint

Full-text available

Feb 2020

Species of Cannabaceae are wind pollinated, have inconspicuous and reduced flowers that are pistillate, staminate and apparently perfect on the same individual or on different individuals, with a single-whorled perianth and a pseudomonomerous gynoecium. Our objective is to understand the developmental processes that lead to such a reduced flower morphology and polygamy in Cannabis sativa, Celtis iguanaea and Trema micrantha. Floral buds and flowers were processed for surface, histological examinations and 3D reconstructions of vasculature. The single-whorled perianth is interpreted as a calyx because the organs are robust, have a broad base, an acute apex and quincuncial aestivation and are opposite the stamens. Petals are absent from inception. The dicliny is established at different development stages: stamens or carpels are absent from inception (Cannabis sativa), initiated and aborted during early (Trema micrantha, before sporo/gametogenesis) or late (Celtis iguanaea, after sporo/gametogenesis) development. Furthermore, in all species studied the carpels are congenitally united and the pseudomonomerous nature of the gynoecium is confirmed. Glandular trichomes are distributed on the bracts, sepals, anther connective and receptacle. Special floral features shared by species of Cannabaceae include precocious ovule development and sepals that are each vascularized by one bundle. The reduced flowers of Cannabaceae are the result of the absence from inception and/or abortion of organs and even of a whole whorl at different developmental stages, which were probably selected in response to pressures exerted by the similar pollination mechanism.

A comparative ontogenetic approach to understanding the pseudomonomerous gynoecium in Moraceae

Article

Feb 2020

Premise of research. Moraceae, the well-known mulberry or fig family, displays small, inconspicuous, diclinous flowers that are very different from many other rosids. One remarkable condition is the gynoecium that is unilocular and uniovulate but composed of two carpels, characterizing a type of pseudomonomery. The pathways that lead to the formation of such a pseudomonomerous gynoecium are insufficiently known. Therefore, the objective of the present study was to elucidate the developmental pathways of this intriguing type of gynoecium in six species representing six of seven tribes recognized in Moraceae: Brosimum gaudichaudii, Castilla elastica, Clarisia ilicifolia, Ficus citrifolia, Maclura tinctoria, and Morus nigra. Methodology. Buds at different stages of development and flowers were processed for surface and anatomical studies. Pivotal results. The gynoecium meristem forms at first a single protuberance in the center of the flower, which then divides, originating two carpels that elongate asymmetrically, but only one initiates an ovule. After elongation of the young carpels, significant differences are found: (1) the two carpels take part in ovary, style, and stigma formation, although only one initiates an ovule in the ovary, and (2) the longer carpel contains an ovule, whereas the smaller carpel is simply a component of the ovary (M. tinctoria). The developed ovary of all species is vascularized by two dorsal traces, attesting to the participation of two carpels. All species except M. tinctoria have two stigmatic branches that, at the time of receptivity, may differ in length. Conclusions. The formation of a pseudomonomerous gynoecium in Moraceae is a condition of carpel dimorphism that manifests itself along an ontogenetic gradient. Such a gradient is evident in the stigma formation, which may involve both carpels, ovulate or not, resulting in symmetrical stigmatic branches or in asymmetrical stigmatic branches, with the shortening or complete absence of one branch. The structure of the pseudomonomerous gynoecium may be the reflection of a balance between the decrease in the number of ovules and the increase and/or maintenance of the equivalent stigmatic surface.

Comparative study of the floral morphology and anatomy in Anacardiaceae, Burseraceae, and Kirkiaceae (Sapindales)

Thesis

Jan 2009

Julien B. Bachelier

Summary This doctoral dissertation focuses on three families of flowering plants, Anacardiaceae, Burseraceae, and Kirkiaceae, which appear all in the same order Sapindales based on recent molecular phylogenetic studies. Currently Anacardiaceae and Burseraceae form a well supported clade. The two genera of Kirkiaceae were earlier placed in another sapindalean family, Simaroubaceae, and the position of Kirkiaceae within the order is still uncertain, either unresolved or sister to Anacardiaceae plus Burseraceae. The present study is the first comparative study of floral morphology and anatomy of Burseraceae, Kirkiaceae, and components of Anacardiaceae, and also the first comparative study of the group in the light of current molecular phylogenetic analyses. The first part concentrates on an enigmatic genus of Anacardiaceae, the wind-pollinated Amphipterygium with puzzling female inflorescences and unique cupular, one-seeded infructescences, which earlier prompted the creation of a separate family, Julianiaceae, consisting of Amphipterygium (earlier: Juliania) and Orthopterygium. However, affinities of the family with Anacardiaceae were obvious before the onset of molecular studies, which showed that Amphipterygium and Orthopterygium are sisters and nested within Anacardioideae, the larger of the two subfamilies of Anacardiaceae. This part tackles two problems. The first is the morphological structure of the complex inflorescences of Amphipterygium whose parts are condensed and variously fused. Our comparative developmental studies revealed that they are thyrsoids, and each cupule represents a few-flowered dichasial-mono-chasial cyme with a single fertile flower, which gives rise to a single fertile seed. The second problem is the relation-ship of Amphipterygium with other Anacardioideae, of which Pistacia has the putatively most similar flowers to Amphipterygium but a critical comparison has never been made. A comparative developmental study of the flowers of both genera showed that similarities are indeed intimate. Both have an unusually large and complex funicle-ovule complex, which shares more similarities in detail than with any other Anacardiaceae studied as yet. This is either a synapomorphy for Amphipterygium and Pistacia or an unusual convergent autapomorphy for each genus. The second part is the first comparative analysis of the floral structure of a representative of the family Kirkiaceae and also the first attempt to discuss their floral features in a broader systematic context. Our results support the position of Kirkiaceae in Sapindales and a putative sister relationship with Anacardiaceae and Burseraceae, as found in a recent molecular phylogenetic study. The most conspicuous shared feature is the development of the gynoecium, which comprises an extensive synascidiate zone and an unusual convex central protrusion derived from the former floral apex, and extending beyond the ovary locules. This may represent a synapomorphy for the potential clade of Kirkiaceae and Anacardiaceae plus Burseraceae. The third part is the most extensive chapter of the thesis. It is a broad comparative study of the floral morphology and anatomy in Anacardiaceae and Burseraceae. In the past, they have traditionally been placed far apart from each other because of their different direction of ovule curvature (apotropous vs. epitropous) and different ovule number (1 vs. 2) per locule. In Anacardiaceae and Burseraceae five and three tribes have traditionally been distinguished. Our results showed that the best supported clades retrieved in molecular phylogenetic studies, i.e., the clade of Anacardiaceae plus Burseraceae, Anacardioideae of Anacardiaceae, the core Burseraceae, and Beiselia as sister to the core Burseraceae, are also best supported by floral features. The clade of Anacardiaceae plus Burseraceae is supported by a number of shared features, es¬pecially in the basalmost representatives of each family. The most conspicuous features are the development of an extensive synascidiate zone in the gynoecium, which extends beyond the ovary locules, and the postgenital union of the free carpel tips. In Beiselia, the position of the former centre of the floral apex is far beyond the locules, whereas it is enclosed in the ovary in core Burseraceae. In Anacardiaceae, the funicle is unusually long with the ovule in median position and the direction of curvature placing its dorsal side in tight contact with the pollen tube transmitting tract of the stylar canal, forming a bridge for the pollen tubes towards the nucellus. The gynoecium in Anacardiaceae differs from that of Burseraceae by a tendency towards monosymmetry and (pseudo)monomery. In Anacardioideae, it is uniformly unilocular, whereas in Spondioideae it is more variable. The presence of unusual features shared by the phylogenetically basal representatives of Anacardiaceae and Burseraceae, and by Kirkiaceae, requires molecular phylogenetic studies with a broader representation of genera. This should provide better resolution of the deepest nodes within this clade and a better understanding of the flower and gynoecium evolution within Sapindales, especially for the development of the centre of the former floral apex and its potential impact on the direction of ovule curvature at anthesis.

Ontogeny and Vascularization Elucidate the Atypical Floral Structure of Ampelocera glabra , a Tropical Species of Ulmaceae

Article

Full-text available

Apr 2018

Premise of research. Ampelocera glabra is an andromonoecious, wind-pollinated species of Ulmaceae, the elm family. This family comprises two clades: tropical and temperate. The species that have been morphologically studied so far all belong to the temperate clade. Ampelocera glabra is included in the tropical clade and is remarkable due to its atypical flower merism when compared to other Ulmaceae and to most other rosids: tetramerous calyx, polyandrous androecium, and pseudomonomerous gynoecium. Thus, our objective was to study the ontogeny and vascularization of the A. glabra flower to elucidate the processes involved in the atypical merism and in the reduced structure of the whorls. Additionally, the mating system of A. glabra was checked and its floral structure was associated with anemophily, thus contributing to reproductive studies of this species under threat of extinction. Methodology. Flowers and early to late floral buds were processed for surface (SEM) and histological (LM) investigations and 3D reconstructions (X-ray microcomputed tomography). Pivotal results. Ampelocera glabra is actually a monoecious species with functionally staminate and functionally pistillate flowers, containing carpellodes and staminodes, respectively. The single perianth whorl is composed of sepals, and there is no hypanthium. Each primordium of the sepals and stamens arises individually. A central common primordium gives rise to two carpels, but only one houses an ovule. Each carpel is vascularized by one dorsal bundle, and the carpel that bears the ovule is also vascularized by one ventral bundle. Thus, the gynoecium displays a reduction in the vascular bundle in the nonovulate carpel. Conclusions. The differences in merism between the calyx and the androecium are explained by the space that can support the increase in organ number. The increase in stamen number and the reduced gynoecium (pseudomonomerous) enable a high pollen∶ovule ratio, which is an important condition for any anemophilous species.

Floral structure of Emmotum (Icacinaceae sensu stricto or Emmotaceae), a phylogenetically isolated genus of lamiids with a unique pseudotrimerous gynoecium, bitegmic ovules and monosporangiate thecae

Article

Full-text available

Aug 2014

Background and Aims Icacinaceae sensu stricto consist of a group of early branching lineages of lamiids whose relationships are not yet resolved and whose detailed floral morphology is poorly known. The most bizarre flowers occur in Emmotum: the gynoecium has three locules on one side and none on the other. It has been interpreted as consisting of three fertile and two sterile carpels or of one fertile carpel with two longitudinal septa and two sterile carpels. This study focused primarily on the outer and inner morphology of the gynoecium to resolve its disputed structure, and ovule structure was also studied. In addition, the perianth and androecium were investigated.

Systematic treatment of morphological fruit types in plants of the class Liliopsida of the flora of Ukraine

Article

Full-text available

Aug 2021

In this review, the scope of morphological diversity of fruits within the class Liliopsida belonging to the flora of Ukraine compared to the world flora diversity was analyzed. For the first time, the taxonomic diversity of monocot plants of the flora of Ukraine was analyzed, which includes 235 genera and about 1050 species, and the distribution of fruit types in the largest monocot families revealed. It was found that among monocot plants of the world flora, as also of the Ukrainian flora, more than 70% of generic and species diversity is taken up by the Orchidaceae, Poaceae, and Cyperaceae families having dry uniform fruits: inferior capsule (Orchidaceae) and one-seeded enveloped fruit (Poaceae and Cyperaceae). An annotated list of morphological fruit types was compiled for all 38 families of the natural and cultural flora of monocot plants of Ukraine. Among 12 families of the subclass Alismatidae, apocarpous polymerous or trimerous fruits, mostly with one-seeded fruitlets, occur in six families (Alismataceae, Butomaceae, Potamogetonaceae, Ruppiaceae, Scheuchzeriaceae, Zannichelliaceae). In 12 of 16 families of the subclass Liliidae, trimerous capsules are the most common (Agapanthaceae, Agavaceae, Alliaceae, Amaryllidaceae, Asphodelaceae, Colchicaceae, Hemerocallidacae, Hyacinthaceae, Iridaceae, Liliасеае, Melanthiaceae, Orchidaceae), while in six families berry-like fruit occurs in all members or in the single genus (Asparagaceae, Ruscaceae, Dioscoreaceae, Melanthiaceae (Paris), Liliасеае (Streptopus), Smilacaceae). Among 10 families of the subclass Commelinidae, in four families superior dry one-seeded fruits occur (Cyperaceae, Poaceae, Sparganiaceae, Typhaceae), while another four families have trimerous capsules (Cannaceae, Commelinaceae, Juncaceae, Pontederiaceae). In general, the most typical fruit on the familial taxonomical level is the capsule (17 families), berries occur in 10 families, aggregate fruits and one-seeded fruits are represented each in seven families, while the rarest fruit type is the schizocarp (Juncaginaceae). No monomerous follicles, poricide and operculate capsules, winged fruits and loments were found. The most controversial fruit types are found in two groups of families, for both of them the problem is the gynoecium type. These are families with one-seeded fruit (Аrасеае (Lemna), Cyperaceae, Hydrocharitaceae (Najas), Poaceae, Sparganiaceae, Typhaceae, Zosteraceae) and families with initial carpel fusion (Hydrocharitaceae (Stratiotes), Juncaginaceae, Melanthiaceae (Veratrum), Scheuchzeriaceae, Tofieldiaceae). As a result of our work, the key and the most relevant areas of carpological studies in Ukraine were defined, particularly, unifying the terminology, examination of the anatomical structure of the pericarp, revealing of the evolutionary and ecological aspects of fruit morphology.

Flower Structure and Development of Spondias Tuberosa and Tapirira Guianensis (Spondioideae): Implications for the Evolution of the Unisexual Flowers and Pseudomonomery in Anacardiaceae

Article

Aug 2021

Premise of research. Anacardiaceae comprise two subfamilies (Anacardioideae and Spondioideae) with small nectariferous flowers that are typically morphologically bisexual, whereas sometimes only the androecium or gynoecium is functional. In most Spondioideae, flowers are typically polysymmetric and obdiplostemonous, with as many antepetalous carpels as there are sepals (or petals), but frequently not all carpels are fertile, and the gynoecium can also be pseudomonomerous or more rarely monomerous. Pseudomonomery has received little or no attention in Spondioideae, and here we compare flowers of Spondias tuberosa, where all carpels form a locule but only one yields a fully developed ovule, and Tapirira guianensis, where only one carpel is fertile. Methodology. In these two species, we studied the flower structure and development using microtome serial sections, and light and scanning electron microscopy. Pivotal results. Both species share morphologically bisexual flowers with a similar floral bauplan and developmental pathway toward functionally male flowers. Their gynoecia share a syncarpous and entirely synascidiate ovary with the former center of the floral apex exposed between the free (and entirely plicate) styles and stigmas. In addition, the position of their single fertile locule varies in each flower and in S. tuberosa remains unclear until the development of the ovules. Conclusions. Functionally unisexual flowers and pseudomonomery likely evolved independently several times in Spondioideae and Anacardiaceae as a whole, and the structural differences between pseudomonomerous gynoecia in each subfamily are the results of heterochronic development. The evolutionary and functional significance of pseudomonomerous gynoecium in Anacardiaceae remains to be explored.

Floral development elucidates the formation of a tubular calyx and connate stamens in Cecropieae species (Urticaceae)

Article

Full-text available

Jul 2020

Small flowers with tubular calyces and connate stamens, a small number of whorls and organs per whorl are found in species of the tribe Cecropieae (Urticaceae). This study elucidates the processes that lead to such floral conditions by comparing the morphology of the developing flowers of Cecropia pachystachya, Coussapoa microcarpa and Pourouma cecropiifolia. Buds and flowers were examined under scanning electron and light microscopy. The tubular calyx originates from the activity of a peripheral annular meristem that results in a tube with two or three lobes. In the staminate floral meristem, the androecium primordium arises as a central bulge that elongates and originates two stamens with the filaments basally or totally united; the anthers can also be united. In the pistillate floral meristem, the gynoecium primordium also arises as a central bulge that elongates and originates two carpel primordia: one expands, forming a cleft and an ovule, and the other does not differentiate and remains rudimentary. Pistillate and staminate flowers result from the absence of the stamen or carpel, respectively, from inception. Petals are also absent from inception. The formation of the tubular calyx and connate stamens occurs very early in development, characterizing a congenital union. The union of anthers by the connectives in C. microcarpa is postgenital and occurs between epidermal cell walls through a weak

Floral development elucidates the formation of a tubular calyx and connate stamens in Cecropieae species (Urticaceae)

Article

Full-text available

Jul 2020
PLANT SYST EVOL

Small flowers with tubular calyces and connate stamens, a small number of whorls and organs per whorl are found in species of the tribe Cecropieae (Urticaceae). This study elucidates the processes that lead to such floral conditions by comparing the morphology of the developing flowers of Cecropia pachystachya, Coussapoa microcarpa and Pourouma cecropiifolia. Buds and flowers were examined under scanning electron and light microscopy. The tubular calyx originates from the activity of a peripheral annular meristem that results in a tube with two or three lobes. In the staminate floral meristem, the androecium primordium arises as a central bulge that elongates and originates two stamens with the filaments basally or totally united; the anthers can also be united. In the pistillate floral meristem, the gynoecium primordium also arises as a central bulge that elongates and originates two carpel primordia: one expands, forming a cleft and an ovule, and the other does not differentiate and remains rudimentary. Pistillate and staminate flowers result from the absence of the stamen or carpel, respectively, from inception. Petals are also absent from inception. The formation of the tubular calyx and connate stamens occurs very early in development, characterizing a congenital union. The union of anthers by the connectives in C. microcarpa is postgenital and occurs between epidermal cell walls through a weak cohesion. The floral development of Cecropieae is quite similar and less labile than in the other Urticaceae species.

Morphological diversity and function of the stigma in Ficus species (Moraceae)

Article

Feb 2018
ACTA OECOL

The stigma plays several roles such as pollen hydration and selection, and pollen tube nutrition. In the Ficus-fig wasp mutualism, stigmata have an additional, almost unknown, function by representing a physical interface for both plant and wasp reproduction. We used light and electron microscopy to compare the detailed morphology of the stigmata of nine Ficus species of different sections and with different pollination modes and sexual expressions. Figs were collected at the stage when the stigmata were receptive for pollination. Stigmata in actively pollinated monoecious species have well developed papillae concentrated on the adaxial surface exposed towards the fig cavity. Conversely, the passively pollinated monoecious species have the whole surface of the stigmata covered by somewhat smaller papillae. In both actively and passively pollinated monoecious species these features are consistent, irrespective of style length. In all actively pollinated gynodioecious species, the stigmata of pistillate flowers were tubular or infundibuliform whereas in almost all actively pollinated monoecious species (except F. racemosa) the stigmata were filiform, with one branch or two asymmetric branches. In gynodioecious species the short-styled flowers in “male” figs show a limited receptive surface with small papillae, while the stigmata of long-styled flowers in “female” figs are covered by papillae that extend down the sides of the style, increasing the stigmatic surface. In actively pollinated species, stigmata are cohesive, forming a common surface for pollen tube germination (= synstigma). The synstigma arrangement was quite variable: lax, cohesive or very cohesive, with entanglement by stigmatic papillae and stylar trichomes. Entanglement by stylar trichomes is common in gynodioecious species. The synstigma arrangement did not correlate with phylogeny or breeding system. This study is the first to report a very loose synstigma in actively pollinated monoecious Ficus species. Our analyses revealed that, in Ficus, the synstigma is functionally analogous to an extra-gynoecial compitum. Comparative studies will be required to test further hypotheses about the evolutionary determinants of such variation.

Gynoecium Evolution in Angiosperms: Monomery, Pseudomonomery, and Mixomery (English translation)

Article

Full-text available

Sep 2017

The presence of a gynoecium composed of carpels is a key feature of angiosperms. The carpel is often regarded as a homologue of the gymnosperm megasporophyll (that is, an ovule-bearing leaf), but higher complexity of the morphological nature of carpel cannot be ruled out. Angiosperm carpels can fuse to form a syncarpous gynoecium. A syncarpous gynoecium usually includes a well-developed compitum, an area where the pollen tube transmitting tracts of individual carpels unite to enable the transition of pollen tubes from one carpel to another. This phenomenon is a precondition to the emergence of carpel dimorphism manifested as the absence of a functional stigma or fertile ovules in part of the carpels. Pseudomonomery, which is characterized by the presence of a fertile ovule (or ovules) in one carpel only, is a specific case of carpel dimorphism. A pseudomonomerous gynoecium usually has a single plane of symmetry and is likely to share certain features of the regulation of morphogenesis with the monosymmetric perianth and androecium. A genuine monomerous gynoecium consists of a single carpel. Syncarpous gynoecia can be abruptly transformed into monomerous gynoecia in the course of evolution or undergo sterilization and gradual reduction of some carpels. Partial or nearly complete loss of carpel individuality that precludes the assignment of an ovule (or ovules) to an individual carpel is observed in a specific group of gynoecia. We termed this phenomenon mixomery, since it should be distinguished from pseudomonomery.

Evolution of angiosperm gynoecium: monomery, pseudomonomery and mixomery

Article

Full-text available

Aug 2017

The presence of a gynoecium composed by carpels is a key feature of angiosperms. The carpel is often viewed as homologous to megasporophyll of gymnosperms (i.e., a leaf bearing ovules), but it is possible that its morphological nature is more complex. Carpels of angiosperms can unite to form a syncarpous gynoecium. Most syncarpous gynoecia possess a compitum, which is a region where pollen tube transmitting tracts of individual carpels unite in a way that pollen tubes can grow from one carpel to another. The presence of a compitum is a precondition for evolution of carpel dimorphism, where some carpels do not possess functional stigma or fertile ovules. Pseudomonomery is a kind of carpel dimorphism where only one carpel has a fertile ovule (or ovules). Pseudomonomerous gynoecium usually has a single symmetry plane and it is likely that regulation of its development is similar to those of monosymmetric perianth and androecium. Monomerous gynoecium consists of a single carpel. In course of evolution, syncarpous gynoecia can jump abruptly to monomerous gynoecia or undergo sterilization and gradual reduction of some carpels. There is a peculiar group of gynoecia with partial or complete loss of carpel individuality, so that it is impossible to assign an ovule (or ovules) to particular carpel. A term mixomery is proposed for this phenomenon, which is not identical to pseudomonomery.

Morfología comparada de diez taxones del género Celtis (Cannabaceae) del Cono Sur Sudamericano

Article

Full-text available

Jul 2021

The genus Celtis L. (Cannabaceae) comprises around 73 species distributed in temperate and tropical regions of both hemispheres. Most South American species belong to the subgenus Mertensia Planch., and they are characterized by showing high morphological plasticity. A recent taxonomic revision of this group was carried out with an excessively reductionist criterion regarding the number of accepted species and that does not clearly reflect the morphological differences among them. In order to contribute to the correct delimitation of the specific entities, a morpho-descriptive approach is presented for ten taxa of the genus Celtis (C. brasiliensis, C. chichape, C. clausseniana, C. fluminensis, C. pallida var. pallida, C pallida var. discolor, C. serratissima, C. spinosa, C. spinosissima and C. tala) growing in South American Southern Cone. The morphology was analyzed through the use of a stereomicroscope and/or the tpsDig program for digital images of specimens. As a result, a key is provided for the determination of the aforementioned species and a detailed morphological description of the vegetative (habit, bark, branches, spines, brachyblasts, indumentum and leaves) and reproductive structures (inflorescences, flowers, fruits and endocarp -pyrene-). In addition, a specimen collection guide is proposed with a list of the main morphological characters that should be observed in the field, to facilitate future identifications.

Development resolves the uncommon floral construction of urticalean rosids

Chapter

Jun 2020

Species of Cannabaceae, Moraceae, Urticaceae and Ulmaceae form the group of urticalean rosids. This group shares the presence of small, slightly showy, diclinous (unisexual), achlamydeous or monochlamydeous flowers, that have a bicarpellate pseudomonomerous gynoecium with a single functional ovule. The flower is considered to be reduced in relation to the other rosids. This study shows that development can explain such an uncommon floral construction of urticalean rosids. Our data are based on studies of at least 20 species, summarized as follows: (1) The monochlamydeous flower results from the absence of a petal whorl from the inception. The interspecific variation in the sepal number is also due to the absence of sepal primordia in the floral meristem. (2) The dicliny results from abortion of stamens and carpels, resulting in staminate flowers with a pistillode and pistillate flowers with staminodes. (3) The pseudomonomerous gynoecium results by the arising of one primordium at the center of the floral meristem that differentiates into two carpels; only one develops normally and produces an ovule while the other does not initiate any ovule, although part of its tissues composes the ovary and even the style and the stigma. (4) The association of the floral organ arrangement with wind pollination is remarkable in the staminate flower of some species. The pistillode inflates during flower development, propelling the anthers enveloped by the sepals outward from the floral center, releasing explosively agglutinated pollen. In the entomophylous species, the union of several stigmas of different flowers forming platforms (Ficus), or the supply of pollen and varied secretions to the pollinating insects (Artocarpus, Castila, Dorstenia) guarantee the formation of seeds. Concluding, floral development is conserved and supports the monophyly of the group. On the contrary, floral specializations are responses to the selection pressures exerted by the different pollinators in the group.

Comparative carpological study of Poikilospermum (Urticaceae) in relation to taxonomy

Article

Full-text available

Apr 2020

Fruit morphology and the anatomical structure of the pericarp, fruiting perianth, and seed coat were studied in 15 species of Poikilospermum, a genus whose position within the Urticaceae has long been controversial. Possible evolutionary trends of their transformation are suggested for both subgenera; plesiomorphies were found in P. oblongifolium and P. scabrinervium. Structural peculiarities of the fruit connected with its ejection out of the tubular perianth are discussed. The archaism of the fruit in Poikilospermum is revealed, indicated, as in Boehmeria, by the presence of the rudiment of an aborted carpel in the form of a large two-lobed rib. Using carpological anatomical characters, the species studied are classified into informal groups, such characters being able to pull the species within the subgenera into rough groupings where gross morphology has been unable to do so. It is shown that heterobathmy may be strongly associated with the genus Poikilospermum. Each subgenus has its own set of primitive carpological characters: in subgenus Poikilospermum the absence of a fruiting perianth which encases the fruit, and also of capitate inflorescences with swollen receptacles; in subgenus Ligulistigma remnant rudiment of the second carpel and ovary loculus, as well as a primitive, less simplified seed coat. Though the position of Poikilospermum as indicated by molecular data is within Urera, our results suggest that Dendrocnide (the only genus of the Urticeae that has a pyrenarium fruit type) may be closest to Poikilospermum, although the pericarp structure and dissemination behaviour in Poikilospermum are more specialised than those exhibited by Dendrocnide. Seed coat structure is also shown to exhibit traits seen in Moraceae.

Development resolves the uncommon floral construction of urticalean rosids

Chapter

Jun 2020

Species of Cannabaceae, Moraceae, Urticaceae and Ulmaceae form the group of urticalean rosids. This group shares the presence of small, slightly showy, diclinous (unisexual), achlamydeous or monochlamydeous flowers, that have a bicarpellate pseudomonomerous gynoecium with a single functional ovule. The flower is considered to be reduced in relation to the other rosids. This study shows that development can explain such an uncommon floral construction of urticalean rosids. Our data are based on studies of at least 20 species, summarized as follows: (1) The monochlamydeous flower results from the absence of a petal whorl from the inception. The interspecific variation in the sepal number is also due to the absence of sepal primordia in the floral meristem. (2) The dicliny results from abortion of stamens and carpels, resulting in staminate flowers with a pistillode and pistillate flowers with staminodes. (3) The pseudomonomerous gynoecium results by the arising of one primordium at the center of the floral meristem that differentiates into two carpels; only one develops normally and produces an ovule while the other does not initiate any ovule, although part of its tissues composes the ovary and even the style and the stigma. (4) The association of the floral organ arrangement with wind pollination is remarkable in the staminate flower of some species. The pistillode inflates during flower development, propelling the anthers enveloped by the sepals outward from the floral center, releasing explosively agglutinated pollen. In the entomophylous species, the union of several stigmas of different flowers forming platforms (Ficus), or the supply of pollen and varied secretions to the pollinating insects (Artocarpus, Castila, Dorstenia) guarantee the formation of seeds. Concluding, floral development is conserved and supports the monophyly of the group. On the contrary, floral specializations are responses to the selection pressures exerted by the different pollinators in the group.

Floral development of Moraceae species with emphasis on the perianth and androecium

Article

Mar 2018
FLORA

The mulberry and fig family (Moraceae) has tiny flowers with a single whorled or absent perianth and inner whorls with a reduced number of organs. Relevant questions about this reduced floral structure still remain unresolved. Thus, we studied the ontogenic processes that culminate in such a reduced flower, as well as the close relationship between the floral envelope and the androecium in Brosimum gaudichaudii, Castilla elastica, Clarisia ilicifolia, Maclura tinctoria and Morus nigra. Flower buds and flowers were processed for surface (scanning electron microscopy) and anatomical (light microscopy) analyses. The perianth consists of sepals, except the flowers of B. gaudichaudii and C. elastica (staminate), in which the perianth is lacking. The staminate flower of B. gaudichaudii exhibits a bracteole enveloping the stamens. In monochlamydeous flowers the order of sepal initiation is helical or asynchronous. No petals are initiated. The calyx displays different degrees of synorganization being united only basally or along its entire extension. The sepals can have tector and glandular trichomes or only tector trichomes. Laticifers, phenolic and crystalliferous idioblasts occur in the sepal mesophyll. Stamens initiate concomitant with the pistillode in B. gaudichaudii and after initiation of the pistillode in M. tinctoria and M. nigra. In C. ilicifolia there is no pistillode and the stamens initiate after the sepals. The stamens show variation in filament shape and connective structure. The filament is inflexed in M. tinctoria and M. nigra and straight in the other species, although these structures are anatomically similar. The connective is expanded (except in M. nigra and C. ilicifolia) and has phenolic idioblasts. We conclude that the tiny flowers of these species result of two distinct ontogenetic pathways: absence of organs from the inception and by abortion, mechanisms that act to decrease the number of floral whorls as well as the number of organs in each whorl.

Taxonomic significance of inflorescences, floral morphology and anatomy in Passerina (Thymelaeaceae)

Article

Full-text available

Dec 2001

Comparative studies were undertaken on the inflorescence, bracts and floral morphology of all taxa of the genus Passerina L. in southern Africa. Information is given in tabular form and a key based on bract morphology is presented. Floral morphology supported the status of tire infrageneric taxa and also proved to be of taxonomic significance in the genus. Controversy Surrounding the interpretation of a number of floral morphological structures in Passerina has been resolved. Morphological and anatomical evidence allowed a re-interpretation of the structure of the receptacle, hypanthium and sepals, ovary type and position, structure of the seed coat, ovule type and position, obturator, fruit and seed. On this basis an authentic generic description of the floral morphology was compiled. Passerina is distinguished by the following set of characters, a very short floral receptacle, tubular hypanthium, petaloid calyx, absence of petals and petaloid scales, diplostemonous dimorphic androecium, extrorse anthers, superior ovary, anatropous, ventrally epitropous, ovule, an obturator of elongated cells, a 1-seeded berry or an achene and tegmic seed with nuclear endosperm becoming cellular throughout. On this basis the flower in Passerina is considered a phylogenetically advanced structure, supporting the view that the genus is advanced within the Thymelaeoideae. The proposed taxonomic relationship between Thymelaeaceae and Malvales is confirmed by floral morphological evidence.

Vascularisation de la fleur d' Orontium aquaticum L. (Aracées)

Article

Jul 2014

Chez Orontium, les fleurs hermaphrodites possèdent 5 ou 6 étamines et 6 tépales. L'ovaire supère contient un ovule hémi-anatrope inséré sur un placenta basal. Le gynécée d'Orontium est généralement tricarpellé. Chaque carpelle comporte un faisceau dorsal et deux faisceaux ventraux. Les neuf faisceaux carpellaires s'individualisent à partir d'un anneau horizontal d'anastomoses situés à la base de la paroi ovarienne. Dans les gynécées bicarpellés, on ne trouve que 5 faisceaux: deux dorsaux, deux ventraux simples et un ventral complexe, résultant de l'union de deux faisceaux ventraux appartenant à des carpelles différents. Ces gynécées sont donc pseudomonomères mais peu condensés. La fleur d'Orontium présente certains points communs avec celle de Calla: ovaire supère uniloculaire, gynécée trimère, organisation vasculaire semblable, placentation basale. D'un autre côté, les gynécées dimères que l'on trouve quelquefois chez Orontium présentent certaines similitudes avec ceux de Lysichitum camtschatckense. Orontium partage certains autres caractères avec Symplocarpus et Lysichitum: fleur périanthée, graine albuminée, pollen monosulqué, nervures de 2ème et 3ème ordres réticulées. Devant ces faits nous préférons, pour le moment, conserver la classification de Krause (1908) qui divise les Calloideae en deux tribus: la première comprend les genres Lysichitum, Symplocarpus et Orontium, la seconde le genre Calla.

Comparative floral structure and systematics of the clade of Lophopyxidaceae and Putranjivaceae (Malpighiales)

Article

Aug 2013

In molecular phylogenetic studies, Lophopyxidaceae and Putranjivaceae are well supported as sisters in the large rosid order Malpighiales. As the floral structure of both families is poorly known and the two families have never been compared, the present comparative study was carried out, as part of a larger project on the comparative floral structure of Malpighiales, using microtome section series and scanning electron microscopy (SEM) studies. Similar to other angiosperm clades, it appears that the structure of the ovules is a strong marker for suprafamilial relationships in Malpighiales. Both families have two collateral pendant antitropous ovules per carpel associated with obturators (as in some Euphorbiaceae s.l., to which Putranjivaceae belonged in earlier classifications). However, in contrast with Euphorbiaceae s.l., the ovules are not crassinucellar, but either incompletely tenuinucellar or only weakly crassinucellar with a long and conspicuously slender nucellus and an endothelium, and do not have a nucellar beak, but a normal micropyle, features they share with families other than Euphorbiaceae s.l. among Malpighiales. Other shared features of the two families include the following. The outer sepals tend to be smaller than the inner ones and the sepals do not protect the gynoecium in older buds. Sepals of some taxa have a single vascular trace. A short zone of synsepaly tends to be present. Stamens tend to be antesepalous in haplostemonous flowers. A short gynophore is present. The synascidiate zone extends up to above the placenta, but is restricted to the ovary in taxa with more than one carpel. The micropyle is formed by the inner integument. The ventral carpel slits extend down into the synascidiate zone as postgenitally fused furrows. The carpels have a broad dorsal band of vascular bundles in the style. The overall floral structure of the two families corroborates their sister position well and does not support the earlier association of Putranjivaceae with Euphorbiaceae s.l. or of Lophopyxidaceae with Geraniales–Sapindales–Celastrales, which rely on shared superficial floral similarities. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172, 404–448.

Entwicklung und Diversität der Blüte

Chapter

Dec 2024

Regine Claßen-Bockhoff

Morphological and taxonomical treatments of fruits in the subclass Rosidae Takht. of the flora of Ukraine

Article

Full-text available

Jun 2023

Anastasiya Odintsova

Introduction. Rosids is the pivotal clade of eudicots, whose taxonomic composition was significantly changed based on molecular phylogeny. Molecular insight led to the re-evaluation of many phenotypic features, especially in reproductive morphology. Although the floral structure and evolution within the current scope of rosids were actively investigated, the morphological structure of fruit was almost fully neglected. The present study aimed to survey the morphological diversity of fruits in rosids (subclass Rosidae) in the flora of Ukraine to reveal the most common fruit types, analyze the distribution of the basic fruit types among rosids, and survey some comparative-morphological features of gynoecium and fruit. Materials and Methods. Fruit features have been surveyed based on many carpological sources. We also analyzed the gynoecium characteristics crucial for fruit development, i.e., the type of ovary insertion, placentation, and ovule and locule number. For Rosidae, seven basic fruit types were recognized using the approach previously elaborated for the monocot plants of Ukraine: aggregate fruit, multi-seeded monocarp, capsule, berry, multi-seeded pyrenarium, schizocarp, and one-seeded fruit. Results. As a result, the annotated list of morphological characteristics for each of the 54 families of Rosidae occurring in Ukraine was composed. In this list, the complementary and the most contrasting definitions of fruits from different sources were combined. Discussion. According to our calculations, the subclass Rosidae in the flora of Ukraine is represented by 326 genera and at least 1617 species. Our results demonstrated that the most widespread fruit types at the family level seem to be capsular and one-seeded fruits, while at genus and species level the portion of multi-seeded monocarps and aggregate fruits is also significant. Nine families reveal more than one basic fruit type in the flora of Ukraine. Some fruits are ambiguously classified into one or another fruit type because of their intermediate features. Thus, fuzzy boundaries between most fruit types are evident. Conclusions. The obtained results have been compared with our previously reported results for the monocot clade in the flora of Ukraine. In both cases, the predominance of capsular fruits at the family-level spectrum of basic fruit types was clearly demonstrated. The results of our analysis suggest that the model of basic fruit types has the potential to be applied to the formal treatment of fruit structure in other groups of angiosperms.

References

Article

Mar 2022

Louis P. Ronse De Craene

Floral morphology is key for understanding floral evolution and plant identification. Floral diagrams are two-dimensional representations of flowers that replace extensive descriptions or elaborate drawings to convey information in a clear and unbiased way. Following the same outline as the first edition, this comprehensive guide includes updated and relevant literature, represents the latest phylogeny, and features 28 new diagrams. Diagrams are presented in the context of the most recent classifications, covering a variety of families and illustrating the floral diversity of major groups of plants. A strong didactic tool for observing and understanding floral structures, these diagrams are the obvious counterpart to any genetic study in flowering plants and to the discussion of major adaptations and evolutionary trends of flowers. This book is invaluable for researchers and students working on plant structure, development and systematics, as well as being an important resource for plant ecologists, evolutionary botanists and horticulturists.

Evolutionary and ecological estimation of fruit structure in monocotyledonous plants of the flora of Ukraine

Article

Full-text available

Oct 2022

Background. Monocot plants in the flora of Ukraine embrace about 1000 species. The members of this group have various fruit types and ways of dissemination. In this review, the results of the evolutionary-morphological analysis of fruits in monocot plants of the flora of Ukraine and their structural adaptations to dispersal are presented. Gynoecium structure and morphogenetic fruit types in monocots. The features of the inner gynoecium structure and the relation between gynoecium and fruit structure were analyzed, and the main problems of fruit classification were detected. It was revealed that apocarpous fruits are often polymerous or oligomerous, composed of 3–6 one-seeded fruitlets. The species with inferior ovary often develop capsular fruits. One-seeded fruits represent the most reduced variant of the gynoecium structure and fruit wall anatomy, providing few structural traits for analysis. Ecological and functional features of fruits in monocots. The characteristics of dehiscent and indehiscent fruits, as well as adaptations to various ways of dispersal: myrmeco-, endozoo-, epizoo-, anemo-, hydro- and autochory are presented. Dehiscent fruits (follicle and capsule) reveal ventral, dorsal or double, dorsoventral dehiscence. One-seeded fruits and fruitlets are often adapted to hydrochory or anemochory. Trends of evolutionary changes of fruits in monocots. The most diverse fruits are found in low-species taxa of early monocots. Within the monocots, we can observe certain evolutionary trends: incomplete carpel fusion, the occurrence of superior one-seeded fruits and inferior many-seeded fruits. Each of these trends may be evoked by adaptations for pollination in gynoecium at the flowering stage. Conclusions. The present evolutionary morphological and ecological studies of fruits in monocot plants of the flora of Ukraine are impeded by controversial structural types of the gynoecium in some species and a scarcity of data on ways of dispersal of fruits and seeds. The precise carpological and carpoecological investigations of the monocots are desirable for many plants of the flora of Ukraine.

A comparative approach reveals diversity of floral developmental processes in Urticaceae

Article

Jun 2022

Most species of Urticaceae, the nettle family, have small and inconspicuous, diclinous flowers, in which the perianth, androecium and gynoecium tend to vary in number. Our objective was to study the morphology of the developing flowers of seven species of Urticaceae to understand the pathways that lead to the different patterns of floral reduction and the complex development of pseudomonomerous gynoecia. Buds and flowers were prepared for electron and light microscopy. Vascularization was studied via high resolution X-ray computed tomography micro-CT. Only one whorl of perianth organs is initiated, except for Phenax sonneratii, the flower of which is achlamydeous; variation in perianth merosity results from absence of organs from inception; dicliny results from the absence of stamens from inception (pistillate flowers) and from pistil abortion at intermediate developmental stages (staminate flowers). The gynoecium results from a primordium that divides partially forming two congenitally united primordia (most species) or from a single primordium that apparently does not divide. The gynoecium is served by a single (four species), or two vascular bundles. This second condition is expected for a pseudomonomerous gynoecium. Pistillode or rudimentary carpels occur in staminate flowers. The comparison among species shows that the developmental processes acting in the floral construction in Urticaceae is diverse.

The development of pseudomonomerous gynoecia: Anacardiaceae (subfamily Anacardioideae) as a case study

Chapter

Mar 2020

The diversity of gynoecium morphology is an important topic of evolutionary biology since this floral organ plays a central role in the reproduction of angiosperms. Gynoecia are called pseudomonomerous when they present only one fertile carpel and more or less prominent traces of sterile carpels, having evolved independently multiple times in angiosperm history. Here we revisit this particular gynoecium feature in the subfamily Anacardioideae (Anacardiaceae) and use the results as a case study to demonstrate how different patterns of development lead to a pseudomonomerous gynoecium and how a detailed morphological analysis can improve our understanding about the mechanisms behind the great floral diversity of the angiosperms. We describe and compare gynoecium development and vasculature in three species of Anacardioideae using SEM and LM. A database from published reports was compiled in order to explore the development of pseudomonomerous gynoecia across major clades. Anacardioideae species have an asymmetrical development of the gynoecium, leading to pseudomonomery; however, all carpels are connected by a compitum. In species belonging to genera like Anacardium and Mangifera, numerous vascular traces indicate that there was a reduction in the number of carpels in this subfamily, from three to one. Similar developmental patterns are addressed in other lineages of angiosperms. This may represent a key evolutionary novelty in Anacardioideae. We also discuss the role of pseudomonomerous gynoecium in a phylogenetic and evolutionary context in other lineages of angiosperms.

Entwicklungsrhythmen von Obstgewächsen in Finnland II. Blütenentwicklung einiger Kultursorten von Ribes nigrum L. und von R. alpinum L. in verschiedenen geographischen Breiten Finnlands

Article

Sep 1968

Otti Zeller

In den Jahren 1962 und 1964 wurden in Finnland an 6 verschiedenen Standorten zwischen dem 60.° und 70.° nördlicher Breite die Blütendifferenzierung und die Blütenentwicklung an einjährigen Langtrieben der Schwarzen Johannisbeersorten Brödtorp und Lepaan musta und der beiden Wildarten Ribes alpinum L. und Ribes spicatum Robson in With. entwicklungsmorphologisch und entwicklungsgeschichtlich geklärt. Die Untersuchungen brachten folgende Ergebnisse: Die Blütenknospen am einjährigen Langtrieb und die Einzelblüten an der Blütentraube zeigen eine ausgeprägte basitone Förderung. Die Blüteninduktion ist abhängig vom Ende der Wachstumsperiode der Langtriebe. Sie beginnt im basalen Triebabschnitt, während das Wachstum am Triebende noch langsam weiterläuft. In Helsinki, in Südfinnland, liegen Blütendifferenzierung und der grösste Teil der Blütenentwicklung noch in der Vegetationsperiode von August bis Anfang Oktober. In den Wintermonaten vollziehen sich weitere Entwicklungsschritte. In Rovaniemi, am Polarkreis, ist die vegetative Wachstumsperiode im extremen Langtag ausgeprägter als in Helsinki. Sie schliesst erst am Ende der Vegetationsperiode ab und die Triebenden verholzen oft ungenügend. Die Blütendifferenzierung setzt wenige Tage vor dem kurzen Herbst ein. Die Blütenanlagen gehen auf sehr niederen Entwicklungsstufen in den Winter. Die jüngsten Blütenanlagen aus der Endzone der Infloreszenz sterben im Winter ab. Die Hauptphase der Blütenentwicklung liegt im Frühsommer des folgenden Jahres. Im Winter besteht keine gesicherte Weiterentwicklung der Blütenprimordien. Untersuchungen an Ribes alpinum am 61.° nördlicher Breite und an Ribes spicatum am 69° 45’ nördlicher Breite zeigen, dass hier Blütendifferenzierung und Blütenentwicklung in der gleichen für den Anbau günstigen Periodizität ablaufen wie in Helsinki.

Waking sleeping beauties: a molecular phylogeny and nomenclator of Halgania (Ehretiaceae, Boraginales)

Article

Full-text available

Apr 2018

Halgania (Ehretiaceae, Boraginales) comprises ~20 species of ericoid shrubs endemic to Australia. The current taxonomic concepts based on morphology are confusing and are sometimes based on misidentification or lack of information about the type material. We describe the morphological diversity and infer relationships using molecular phylogenetics. The five petals in all Halgania species are blue to violet (rarely white). The yellow or yellow-purple anthers are connected into a cone surrounding the single style. Differences among the species are mainly found in the indumentum of the plants, the leaf margin (i.e. degree of serration), the sepals (being either of equal or of unequal size) and the length of the beak-like anther appendages. A phylogenetic tree mainly based on ITS sequences retrieves three highly supported groups. The H. andromedifolia clade uniquely has sepals of unequal size, and the H. anagalloides clade exhibits dolabriform trichomes. The remaining taxa (constituting the H. littoralis clade) lack such diagnostic morphological traits, but are reliably retrieved as sister group to the H. anagalloides clade. As a first step towards the taxonomic revision of Halgania, we have compiled a nomenclatural list of all validly published names (at the species level and below), provide information about herbarium deposition of original material and discuss the current use of the names.

PISTIL DEVELOPMENT AND PARIETAL PLACENTATION IN THE PSEUDOMONOMEROUS OVARY OF ZELKOVA SERRATA (ULMACEAE)

Article

Aug 1992

Development of female flowers in Zelkova serrata was observed using epi-illuminated microscopy and scanning electron microscopy, with particular attention given to placentation. After the inception of staminodial primordia, the floral apex becomes flat, and the first and subsequently the second carpel primordia appear at opposite comers of the pistil primordium. Inside each carpel primordium a fossette forms. Through differential growth this depression becomes clear and the carpel wall encircles one side of the future placental region. The placental region is detectable even in early stages, but clear signs of ovule inception appear late when the placental region is elevated onto one side of the ovary wall by intercalary growth. Although the relative size of the two carpels varies among flowers, the placental position always appears to be the border between the two carpels and the floral apex. This suggests that the placentation of Zelkova is parietal. The ovule position in tricarpellate ovaries also suggests an evolutionary derivation from ovaries with parietal placentation. Parietal placentation appears to be the original condition in Urticales.

STUDIES IN THE FLORAL MORPHOLOGY OF THE THYMELAEACEAE

Article

Feb 1951

Katherine H. Heinig

INFLORESCENCE AND FLOWER DEVELOPMENT IN THE PIPERACEAE III. FLORAL ONTOGENY OF PIPER

Article

Oct 1982

Shirley C. Tucker

Floral development in Piper was compared between four-staminate species (P. aduncum and P. marginatum) and six-staminate species (P. amalago). All Piper species have a syncarpous gynoecium composed of three or four carpels. The floral apex is initiated by a periclinal division in the subsurface layer in the axil of a bract 40-55 μm high; initiation of the bracts occurs separately and considerably earlier. The floral primordium widens and the first pair of stamens are initiated at either side. The median anterior stamen forms next, and the median posterior later. This sequence is common to all species studied. In the six-staminate P. amalago, the last two stamens form simultaneously in lateral-anterior positions. The stamens hence arise as pairs, and symmetry is bilateral or dorsiventral. The three or four carpels arise simultaneously; they are soon elevated on a gynoecial ring by growth of the receptacle below the level of attachment of the carpels to produce a syncarpous gynoecium. The floral apex lastly produces the solitary basal ovule and is used up in its formation.

Developmental morphology of female flowers of G yrostemon and Tersonia and floral evolution among Gyrostemonaceae

Article

Nov 1996

Larry Hufford

Floral simplifications and specializations in the evolution of Gyrostemonaceae have confused the systematics of the family. Recent phylogenetic analyses have demonstrated their placement among Capparales. This investigation presents a phylogenetic analysis of Gyrostemonaceae, demonstrating that Codonocarpus and Gyrostemon form a clade that is the sister group of Cypselocarpus, Tersonia, and Walteranthus. These phylogenetic results and data on development of Gyrostemon and Tersonia are used to discuss the morphology and evolutionary diversification of female flowers of Gyrostemonaceae. The uniseriate perianth of Gyrostemonaceae consists of four to eight tepals with an unusual lateral to median developmental sequence. The female flowers of Gyrostemon and Tersonia display no distinctive evidence of an androecium, although the former has late-forming, primordium-like structures positioned between the tepals and gynoecium that may be the vestiges of either a second perianth series or the androecium. The gynoecium of Gyrostemonaceae is syncarpous, although the two main clades in the family differ in the expression of ovarian synorganization. The Codonocarpus–Gyrostemon clade is unusual in having largely separate carpels that are only syncarpous because the ventral side of each is formed by the flank of the floral apex. All Gyrostemonaceae, however, incorporate the flank of the floral apex as the ventral side of the carpel, and this is the location of ovule development. On the basis of its placement in a clade that includes Tersonia and Walteranthus, the uniloculate and uniovulate gynoecium of Cypselocarpus may be pseudomonomerous. All Gyrostemonaceae have large stigmas that are typical of anemophilous taxa, and they differ from most other Capparales in this attribute. Among Capparales, Gyrostemonaceae may be most similar to Ochradenus (Resedaceae), which also appears to be anemophilous. It is unclear whether the similarities of Ochradenus and Gyrostemonaceae are homologies, indicative of a close relationship between the two groups, or evolutionary parallelisms associated with separate shifts to anemophily.

POLLEN MORPHOLOGY IN THE SELAGINEAE, MANULEAE (SCROPHULARIACEAE), AND SELECTED GLOBULARIACEAE, AND ITS TAXONOMIC SIGNIFICANCE

Article

Jun 1993

Charles Argue

The pollen grains of 22 genera and 182 species of Selagineae, Manuleae, and selected Globulariaceae were examined by light and scanning electron microscopy of whole and fractured pollen. Grains of the Selagineae and most Manuleae have trizonicolporate aperatures with long, unconstricted ectocolpi; clearly delimited margos; psilate colpus membranes; lalongate transverse endocolpi extending beyond the boundaries of the ectocolpi; thickened endoaperture margins; semitectate, reticulate to microreticulate exines; and psilate, simplicolumellate muri. In the Globulariaceae, Globularia has spinulose, microperforate exines and undifferentiated ectocolpus margins, and both Globularia and Poskea have granular to spinulose colpus membranes, lolongate endoapertures included within the ectocolpi, and unthickened endoaperture margins. These pollen data support postulated relationships between Selagineae and Manuleae, but pollen grains of Selagineae and Globulariaceae are distinct, and pollen morphology does not correlate with proposals combining these taxa in Globulariaceae or Selaginaceae. Pollen morphology in Glumicalyx is indistinguishable from that in most Manuleae and supports transfer of this genus to the Manuleae from the Digitaleae. Differences in pollen morphology supplement established morphological distinctions between Globularia and Poskea, but the pollen evidence does not support published infrageneric classifications in Globularia or postulated relationships between Selagineae and Gratioleae or Selagineae and Lagotis.

INFLORESCENCE AND FLOWER DEVELOPMENT IN THE PIPERACEAE. I. PEPEROMIA

Article

May 1980

Shirley C. Tucker

Flowers of Peperomia species are the simplest structurally of any of the members of the Piperaceae. The spicate inflorescences form terminally and in axillary position; in each, the apex first is zonate in configuration with a two-layered tunica while 3-4 leaves are initiated. Later, when the inflorescence apical meristem begins bract initiation, the biseriate tunica persists, but zonal distinctions diminish and the apex can be described in terms of a simple tunicacorpus configuration. The inflorescence apex aborts after producing 30-40 bracts in acropetal succession an abscission layer forms across the base of the apex, and the meristem dries and drops off. Bracts are produced by periclinal divisions in T2 (and occasionally also in the third layer as well); the later-formed floral apices arise by periclinal divisions in T2 and the third layer. Each floral apex is at first a long transverse ridge in the axil, perpendicular to the long axis of the inflorescence. This establishes bilateral symmetry in the flower, which persists throughout subsequent growth. The floral meristem becomes saddle-shaped, and two stamen primordia are delimited, one at either end and lower than the central floral apex. A solitary carpel is initiated abaxially, and soon forms a circular rim which heightens as a tube with an apical pore. Within the open carpel, a solitary ovule is initiated from the entire remains of the floral apical meristem; it, hence, is terminal in the flower, and its placentation is basal. Carpellary closure in P. metallica results from accelerated growth of the abaxial lip, and the two margins become appressed. Species differ greatly as to whether the abaxial or the adaxial lobe predominates in late stages of carpel development. In P. metallica, the receptive portion of the stigma forms from the shorter lobe which is overtopped. Stigmatoid tissue forms internal to the receptive stigma. The prevailing bilateral floral symmetry, absence of a perianth, and the spicate inflorescence are features which distinguish Peperomia (and Piperaceae) from the magnolialian line of angiosperms.

DISPERSAL ECOLOGY OF VANCOUVERIA (BERBERIDACEAE)

Article

Feb 1972

Rolf Y. Berg

All Vancouveria species are habitual myrmecochores of the Viola odorata type. The anatropous, bitegmic seed develops an unusual elaiosome in the form of a large, empty, folded and lobed sac of epidermal tissue. The thin-walled assimilating capsule dehisces along an oblique weak zone that probably represents the suture between two fused and unequal carpels. In V. hexandra the capsule opens early to expose immature assimilating seeds. Decurved pedicels, down-turned fruits, and weak funiculi produce tachyspory. The related Epimedium, Jeffersonia, and Plagiorhegma have appendaged seeds and other possible myrmecochorous features resembling those of Vancouveria. Myrmecochory was probably established in the early or middle Tertiary period. The Vancouveria-Epimedium complex indicates that enormous plant migrations may be accomplished by means of ants.

A Phylogenetic Classification of the Annoniflorae

Article

Jan 1974

Robert Thorne

Aroid floral morphogenesis in relation to phylogeny

Chapter

Jan 2011

Denis Barabé

What is the link between morphogenesis and phylogeny? This question was addressed by Haeckel, in the nineteenth century, when he formulated his controversial biogenetic law, stating that ontogeny is a short and rapid recapitulation of phylogeny (Haeckel, 1866). Since that time, many zoological and botanical studies discussing the idea of the usefulness of ontogeny in determining phylogeny have been published (e.g. Gould, 1977; Nelson, 1978). Ontogenetic features have been used, for example, to determine the phylogenetic relationships of Saururaceae and Piperaceae (Tucker et al., 1993). On the other hand, Mishler (1986) considered that an independent phylogeny should be established to adequately interpret the evolution of ontogenetic characters. In the present chapter, I will address this general question by using the floral morphogenesis of Araceae as a case study. The Araceae family comprises 117 genera and nearly 3300 species (Haigh et al., 2010). In recent phylogenies, Araceae belong to the Alismatales and are positioned as a sister group of the rest of the order (Stevens, 2001). The family includes eight subfamilies: Gymnostachydoideae, Orontioideae, Lemnoideae, Pothoideae, Monsteroideae, Lasioideae, Zamioculcadoideae and Aroideae, if we accept the recently proposed Zamioculcadoideae (Bogner and Hesse, 2005, Cusimano et al., 2011).

Gradual vs. abrupt reduction of carpels in syncarpous gynoecia: A case study from Polyscias subg. Arthrophyllum (Araliaceae: Apiales)

Article

Full-text available

Dec 2016
AM J BOT

PREMISE OF THE STUDY: Revealing the relative roles of gradual and abrupt transformations of morphological characters is an important topic of evolutionary biology. Gynoecia apparently consisting of one carpel have evolved from pluricarpellate syncarpous gynoecia in several angiosperm clades. The process of reduction can involve intermediate stages, with one fertile and one or more sterile carpels (pseudomonomery). The possible origin of monomery directly via an abrupt change of gynoecium merism has been a matter of dispute. We explore the nature of gynoecium reduction in a clade of Araliaceae. METHODS: The anatomy and development of unilocular gynoecia are investigated using light and scanning electron microscopy in two members of Polyscias subg. Arthrophyllum. Gynoecium diversity in the genus is discussed in a phylogenetic framework. KEY RESULTS: Unilocular gynoecia with one fertile ovule have evolved at least four times in Polyscias, including one newly discovered case. The two unilocular taxa investigated are unicarpellate, without any traces of reduced sterile carpels. Carpel orientation is unstable, and the ovary roof and style contain numerous vascular bundles without clearly recognizable dorsals or ventrals. In contrast to pluricarpellate Araliaceae and Apiaceae, the cross zone is apparently oblique in the unicarpellate species. CONCLUSIONS: No support was found for gradual gynoecium reduction via pseudomonomery. The abrupt origin of monomery via direct change of gynoecium merism and the unstable carpel orientation observed are related to the general lability of the flower groundplan in Polyscias. The apparent occurrence of the unusual oblique cross zone in unicarpellate Araliaceae can be explained by developmental constraints.

TOWARD ThE PRiNCiPLES OF SyNCARPOuS gyNOECiA CLASSiFiCATiON [in Ukrainian: До питання про принципи класифікації синкарпних гінецеїв]

Article

Full-text available

Jan 2012

Anastasiya Odintsova

Abstract. The directions of broadening of the classifcation of syncarpous gynoecia on the base of the concept of vertical zonality subject to the constructional variants have been discussed.

Structural transformations of the syncarpous gynoecium of Dicotyledones toward oligomerisation and reduction [in Russian: Структурные преобразования синкарпного гинецея двудольных в направлении олигомеризации и редукции].

Conference Paper

Sep 2006

Anastasiya Odintsova

Two trends to the carpels and ovules oligomery in the syncarpous gynoecium were described that lead to the formation of diverse types of the pseudomonomerous gynoecium. As an initial stage we have accepted the syncarpous gynoecium with synascidiate, symplicate and apocarpous zones, with two first zones in the ovary and multiovulate axial and parietal placentae. The first trend includes the consecutive reduction of all axial placentae, synascidiate zone and reduction all parietal placentae, except one. The resulting gynoecium is unilocular, often uniovular, but really bicarpellate. The second trend consists in consecutive reduction of all parietal placentae, symplicate zone in the ovary, sterilization all carpels, except one. The resulting gynoecium is really monomer, but derived from syncarpous oligomer gynoecium.

Die morphologische Analyse

Chapter

Jan 1951

Dr. phil. Franz Buxbaum

Wie oben ausgeführt wurde, kommt der morphologischen Analyse gerade bei der Erneuerung der Systematik das überragende Primat über alle anderen als Hilfswissenschaften herangezogenen Disziplinen zu. An diesem Grundsatz muß vor allem festgehalten werden. Da aber anderseits gezeigt werden konnte, daß das, was man in den Jahrzehnten vor Trolls bahnbrechender Erneuerung als „Morphologie“ bezeichnete, nichts anderes als, sagen wir eine „beschreibende Terminologie” war, die nichts mehr mit der von Goethe begründeten vergleichend morphologischen Wissenschaft zu tun hatte, ist es für den Systematiker von heute absolut unerläßlich, sich in die „Vergleichende Morphologie“ im Sinne Trolls gründlich einzuarbeiten, d. h. Trolls Hauptwerk, aber ganz besonders auch die späteren (und früheren) Arbeiten Trolls und seiner Schule durchgearbeitet zu haben.

Valerianaceae

Chapter

Apr 2016

Annual to perennial, often fetid herbs, subshrubs, sometimes shrubs, rarely ligneous or herbaceous vines; root often a taproot, often slender, sometimes a napiform or fusiform turnip, the stem-borne roots sometimes tuberous; plants often semirosulate, sometimes rosulate; stem often fistulous. Leaves mostly decussate, rarely 3-verticillate, sometimes alternate, rarely distichous or tristichous, entire, pinnatifid or pinnate, exstipulate, rarely ericoid or carnose, glabrous or with simple and glandular hairs. Inflorescence usually bracteate, a dense thyrse or pleiothyrse without terminal flower, basimesotonic or acrotonic and pseudodichotomous, sometimes capitate by condensation of the flower-bearing branches; in some genera supernumerary bracts occur below the flowers. Flowers epigynous, bisexual or unisexual, then plants dioecious, polygamous or often gynodioecious, basically pentamerous, but altered by reduction of organs, usually irregularly zygomorphic; calyx rarely regularly 5-lobed, mostly inconspicuous or strongly reduced, or often divided into up to 30 segments, inrolled during anthesis; corolla sympetalous, funnelform, infundibuliform, salverform, rotate or campanulate, tube often saccate at base and nectariferous inside, sometimes spurred, limb with 3 or 5 more or less unequal lobes, often bilabiate; stamens 1–4(5), usually inserted in the corolla tube, alternating with the corolla lobes, anthers tetrasporangiate or rarely bisporangiate; ovary inferior, 3-locular, one locule with 1 pendent ovule, the other two sterile, often very small; style 1, filiform with a two- or three-lobed stigma. Fruit an achene with a persistent, usually accrescent calyx, sterile locules persistent, sometimes inflated, or apparently absent; the calyx mostly developing into a plumose or awned pappus (segments inrolled in flower) or a solid rim, or consisting of 5 regular teeth or fewer or more irregular lobes, sometimes 1–3 stout horns or a small or larger number of spines, sometimes regularly 6-lobed and coroniform, rarely inflated. Mature seed usually without endosperm, rarely endosperm copious; embryo large, straight.

Flowering Plants · Dicotyledons

Chapter

Jan 2003

B. E. Herber

Trees, shrubs, lianas, or rarely herbs, evergreen or deciduous, usually poisonous, often with intraxylary phloem, more rarely also with interxylary phloem. Leaves alternate or opposite, petiolate or sessile, simple, entire, exstipulate; secondary veins occasionally terminating in a marginal vein. Inflorescences usually indeterminate or rarely with terminal flowers; bracts often forming an involucrum, rarely completely reduced. Flowers hermaphroditic or unisexual; floral tube usually present, often conspicuously coloured, short and cupular in Octolepidoideae and extended in Thymelaeoideae, occasionally articulated above ovary, deciduous or fully to partly persistent in fruit; sepals (3)4–5(6), imbricate or more rarely valvate; petals either fully developed or strongly to totally reduced, as many as, twice as many as, or even more than twice as many as sepals, sometimes united below or fused to form an annulus, inserted on rim of the floral tube, the upper portion of floral tube, or at receptacle; androecium diplostemonous, haplostemonous, polystemonous, or stamens rarely 2 or 1, in Thymelaeoideae inserted in upper portion of floral tube (except Synandrodaphne) and in Octolepidoideae at receptacle; antesepalous stamens sometimes adnate to base of sepals; filaments long, short, or anthers sessile, rarely fused to form a tube; anthers straight, reflexed, peltate or horseshoe-shaped, usually 4-sporangiate, introrse or rarely extrorse, basifixed or rarely dorsifixed; floral disk variable in shape or absent; ovary in Octolepidoideae 3–12-locular, in Thymelaeoideae 1- or 2-locular, sometimes stiped, glabrous to pubescent; ovules anatropous, axile, 1 per locule; style present or very rarely absent, inserted terminally or laterally on ovary; stigma often papillose; carpels sometimes provided with dorsal effigurations (“parastyles”). Fruit a loculicidal capsule with up to 9 locules, or indehiscent, 1(2)-locular; seeds 1 per locule, with or without aril-like appendix arising from chalaza or raphe; seed coat glabrous or in taxa with dehiscent fruits often pubescent, crustaceous or more rarely membranous; cells of inner epidermis usually with stripes on inner surface; endosperm copious to absent; cotyledons thick or thin; radicle very short or rarely elongated.

Interpretative gynoecial morphology of Lactoridaceae and Winteraceae – A re-assessment

Article

Apr 1971

A. D. J. Meeuse

An analysis of the floral morphology of a number of Polycarpicae, based on numerous published reports, reveals that the interpretative morphology of the pistils of Winteraceae, Lactoridaceae and some associated groups must be based on the assumption that these female reproductive organs are lateral appendages of gonoclads which became laterally concrescent to form a spurious floral apex. Certain anatomical and comparative morphological details are in good agreement with this interpretation. The pistils in question, inserted on the false floral apex, can only be the homologues of ovuliferous cupules as found in Mesozoic cycadopsid gymnosperms. This type of floral organisation and this category of pistil occur in a number of Polycarpicae, but almost certainly not in all taxa of this assembly, and also in several other angiospermous groups. The implications of this interpretation in the early divergent Angiosperm phylogeny and in the taxonomy of the Flowering Plants are discussed.

Evolution and Phylogeny of the Araceae

Article

Jan 1990

Michael H. Grayum

The Araceae are exceptionally diverse by nearly all phenetic criteria. The two most widely accepted infrafamilial classification systems, those of Engler and Hutchinson, emphasize vegetative and floral morphology, respectively, and are thus rather dissimilar. A more balanced scheme, in which all available phenetic data are considered, is attempted here. Character state polarities are inferred, and synapomorphies utilized to circumscribe infrafamilial taxa. Among the character states considered primitive for Araceae are: a rhizomatous or caulescent growth habit; simple, cordate leaf blades; parallel venation; a simple, green spathe; bisexual, perigoniate flowers; trilocular ovaries with axile placentation; anatropous, crassinucellate ovules; elongate stamens with longitudinal anther dehiscence; a base chromosome number of x = 7 or 14; and monosulcate, reticulate, binucleate pollen grains lacking starch. These and other conclusions have been employed in a character analysis of araceous subtaxa accepted a priori as natural. Significant features of the classification derived from a cladogram reflecting this analysis include: the merger of Engler's subfamilies Pothoideae and Monsteroideae, and the dissolution of his Calloideae; a drastic internal rearrangement of the Colocasioideae; and the recharacterization of the Aroideae, involving the transfer of several tribes to the Philodendroideae and the assimilation of the subfamily Pistioideae (Pistia stratiotes L.) and the tribe Thomsonieae (formerly included in subfamily Lasioideae). The following suprageneric nomenclatural novelties are created: Cercestideae Grayum, trib. nov.; Protarinae (Engl.) Grayum, stat. nov.; Remusatiinae Grayum, subtrib. nov.; Jasarinae Grayum, subtrib. nov.; and Scaphispathinae Grayum, subtrib. nov.

The Carpel: A Problem Child of Floral Morphology and Evolution

Article

Dec 1989

In line with the philosophy of character research and previous work on the character "carpel-form", with its character-states leptate, pseudoleptate and coenoleptate carpel-form, it was decided to reconsider the concepts "carpel" and "gynoecium". The carpel, and the carpel-types as well as the gynoecium and the gynoecium-types are approached as character-complexes, viz. sets of characters and characterstates which stand in close hierarchic relation to each other. Within the presented conceptual framework the description of the carpel as an ovuliferous phyllome is commented on, because in the array carpel-type, carpel and ovuliferous phyllome both the carpel and the ovuliferous phyllome are non-interchangeable character-complexes. On the other hand it is argued that alternative approaches to the carpel and the gynoecium do not contribute to the delineation of systematically relevant types. Apart from the development of our view on the carpel and related concepts, the advantages of the new approach are discussed.

Understanding the structure of flowers—The wonderful tool of floral formulae: A response to Prenner & al.

Article

Full-text available

Oct 2014

This paper is a discussion and elaboration of a paper by Prenner & al. (2010), entitled “Floral formulae updated for routine inclusion in formal taxonomic descriptions”. The aim of the Prenner paper was to promote the use of floral formulae in botany and to reach a consensus among botanists for best practice. An important purpose of floral formulae is to induce users to observe and describe flowers accurately. It is proposed that additional information on anther, ovule, style and stigma should be included. Also, only visible organs should be included in a formula and theoretical speculations should be illustrated with floral diagrams, which are complementary to formulae, unless there is good reason to include absent organs. We propose a universal, standardized method to accurately shorthand a description of a flower. The level of detail given in the formula can be highly flexible and depends on the intentions of the user.

Blütenmorphologie — Rückblick und aktuelle Probleme

Article

Oct 1977
PLANT BIOLOGY

Peter K Endress

Untersuchungen über Morphologie, Entwicklungsgeschichte und systematische Bedeutung des pseudomonomeren Gynoeceums

No full-text available

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