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Pollen morphology of Brazilian Aristolochia subgenera Aristolochia (Aristolochiaceae) and its taxonomical significance
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Abstract
Aristolochia (Aristolochiaceae) comprises about 550 species and especially in the Neotropical region where this genus is highly diverse few studies of palynological characterization have been conducted. To better understand the pollen morphology of the genus, pollen grains of 25 species were examined, of which one belongs to Aristolochia subgenus Siphisia and 24 to Aristolochia subgenus Aristolochia (three of Aristolochia series Thyrsicae; eight of Aristolochia series Hexandrae subser. Anthocaulicae , and 13 of Aristolochia series Hexandrae subseries Hexandrae ). Pollen grains are radially symmetrical, apolar, inaperturate and spheroidal. Under SEM, ornamentation patterns of the exine are fossulate (19 species), fossulate-areolate (four species), microfossulate (one species) and verrucate (one species). Most species have pollen with perforated surface except A. gibertii , A. holostylis , A. pohliana , and A. ridicula . Results corroborate that the micromorphological features, such as pollen shape and aperture absence are similar in all species of Aristolochia , but for some species exine ornamentation might be useful for taxonomic distinction at the species level.
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Flowers of most Aristolochia species possess six stamens and six carpels; however, the c 40 species of subsection Pentandrae, which grow in S United States, Mexico, N Central America, Cuba, and Jamaica, have flowers with five stamens and five carpels. The sister group of this subsection consists of five hexandrous species from subtropical and temperate areas of South America, thus matching the puzzling temperate South America-Temperate North America disjunction. The synapomorphies that support such sister-group relationship and the monophyly of subsection Pentandrae are described. An important range extension of A. pentandra Jacq., which was recently found in the Island of San Andrés (Colombia), is reported, and an update of the description and typification of this species is provided.
Two new occurrences of Aristolochia in Brazil are reported here. Aristolochia cremersii, hitherto known from French Guiana, was collected in Oriximiná/Pará, and A. argentina, with previously known distribution in Argentina, Bolivia and Paraguay, was recorded in Bodoquena/Mato Grosso do Sul. The latter species was identified based on photographic records. We provide descriptions, morphological comments, a preliminary extinction risk assessment (with one of them applying the rapid Least Concern method) and illustration/images of the 2 species, and finally discuss the use of photographs as valuable scientific records.
The pollen and orbicule morphology of the Korean Piperales (Aristolochia, Asarum, Houttuynia, Piper, and Saururus) were investigated via scanning electron microscopy. Piperales pollen is a monad, its size ranging from very small to large (P = 7.78–51.4 μm, E = 6.68–43.1 μm), and having a mainly circular to sub-circular shape. The aperture type is constant in the genus [inaperturate (Aristolochia), tri to pentaporate (Asarum), and monosulcate (Houttuynia, Piper, and Saururus)]. There are four distinct types of exine ornamentation: Fossulate with perforate, microreticulate with gemmae, microperforate with granula, and microechinate. The orbicules (minute sporopollenin granules) were observed in all studied taxa and thus, may be a possible symplesiomorphic characteristic of Piperales. Further, the observed orbicule surface ornamentation was similar to pollen exine patterns, for example muri, gemmae, or granula. This resemblance between orbicule and pollen exine ornamentation may imply a similar biosynthesis pattern of sporopollenin of pollen exine and orbicules. The phenogram resulting from a cluster analysis using palynological characters was generally consistent with the known molecular phylogeny of Piperales. This initial study will help understand the palynological diversity and provide detailed information of pollen and orbicule characteristics in Piperales.
Pollen ultrastructure has been studied in two relict and rare species of the genus Aristolochia, A. contorta Bunge and A. manshuriensis Kom. (Aristolochiaceae). Both species have inaperturate, spheroidal, sometimes distally monocolpate or distally bicolpate pollen grains. The equatorial and polar axes of pollen grain in A. manshuriensis are 48.5 and 44.0 μm, respectively. The percentage of defective pollen grains in A. manshuriensis is 3.4%. The fossulate, perforated exine is up to 2.3 μm in thickness; the sexine and the nexine are almost equal in thickness. In A. contorta, the equatorial axis of pollen grain is 36.6 μm: the defectiveness percentage, 24.5%. The exine is verrucate, up to 0.3 μm in thickness, while the sexine is two to three times thicker than the nexine. The pollen germination experiments have shown that pollen of A. manshuriensis, in contrast to A. contorta, can germinate in 10–20% sucrose at 22°С. These data and the high percentage of pollen defectiveness in A. contorta indicate that the androecium function in this species is reduced. The reduction of the androecium function is evidenced by a small amount of pollen grains in anthers or empty anthers and a high percentage of defective pollen grains.
Two Aristolochia species are distinguished by microsporogenesis types and time of aperture initiation in the sporoderm development. A. clematitis has successive meiosis and forms an aperture in the late free microspore stage when the intine is maturing. A. manshuriensis has simultaneous microsporogenesis and forms aperture regions in the middle tetrad stage. However, the endexine and intine develop uniformly all over the pollen grain without any differences indicating aperture regions. Strong slowing of intine development at the end of pollen ontogeny allows pollen of A. clematitis to have an aperture which had not been formed at first. Pollen grains of A. manshuriensis, which are tardy up to the stage of intine initiation, do not have enough time to form any aperture in last stages of endexine and intine development. Only deep cracks in the ectexine weakly remind of apertures in A. manshuriensis.
A cladistic analysis of the subfamily Aristolochioideae (Aristolochiaceae) based on morphological characters is presented. The analysis includes 65 taxa within the ingroup, which represent all the tribes, subtribes, genera, and infrageneric taxa formally described within the subfamily Aristolochioideae sensu Schmidt. The analysis shows that Aristolochia s.l. is paraphyletic and that Euglypha and Holostylis are not different lineages from Aristolochia. Two of the three subgenera recognized within Aristolochia (Siphisia and Pararistolochia) are shown to be monophyletic. The third subgenus (Aristolochia) is paraphyletic. Most taxa at lower rank levels (sections, subsections, series, and subseries) are shown to be either polyphyletic or paraphyletic. The characters traditionally used for the recognition of these taxa are evaluated and new characters are introduced. Finally, a revised system of classification of the Aristolochioideae based on monophyletic groupings and consisting of two tribes, two subtribes, and five genera is proposed here.
Recently, evolutionary relationships among the five major lineages of the basal angiosperms, i.e., Amborellanae, Nymphaeanae, Austrobaileyanae, Magnolianae, and Ceratophyllanae, still remain incompletely or controversially resolved. This study reviews and reevaluates the origin, evolution, and systematic significance of pollen morphology in basal angiosperms. Pollen grains from 34 species of 31 genera in 23 families of the basal angiosperms are investigated, using light microscopy (LM) and scanning electron microscopy (SEM), to illustrate the pollen diversity across the grade. Pollen data for 57 genera, representing all nine orders and 28 families of the basal angiosperms, were obtained from previous work and new investigations and were used to optimize character states onto recent molecular phylogenetic estimates. Two 18-character datasets were generated: a comprehensively coded dataset optimized with Fitch parsimony onto 12 recent phylogenies with differing topologies to evaluate the degree of pollen systematic significance of each topology, and a democratically coded dataset optimized by using Fitch parsimony, maximum likelihood, and hierarchical Bayesian inference onto a single recent phylogeny based on molecular data from Soltis et al. to evaluate the disparity of pollen evolutionary patterns among the three methods. Pollen morphology of the basal angiosperms is highly diverse, particularly in terms of pollen size, aperture number, aperture position, ectoaperture shape, tectum sculpture, and infratectal structure. Based on both datasets, the plesiomorphic pollen type for angiosperms was inferred to comprise monads of heteropolar, spheroidal, mono-apertural grains, with distal, colpate apertures, sculptured aperture membranes, and an infratectum and foot layer. Of the basal angiosperm phylogenies considered, when taxon sampling is taken into account, pollen characters provide greatest support for the topology represented in the three-mitochondrial-gene study from Qiu et al., in terms of number of synapomorphies plus what we term “likely synapomorphies” in which the subtending node is ambiguous and, therefore, the exact position of the synapomorphy is ambiguous. Thirty-six various lineages above family level are supported by pollen morphological synapomorphies or likely synapomorphies. We discuss the systematic significance of pollen morphology in basal angiosperm clades including the ANITA group (Amborellaceae, Nymphaeaceae, Schisandraceae, Trimeniaceae, and Austrobaileyaceae), Ceratophyllales, Chloranthales, and magnoliids, as well as in related lineages, i.e., monocots and basal eudicots. We also discuss present limitations in inferring the evolutionary history of pollen morphology in basal angiosperms.
Aristolochia longispathulata, a new species from the "Mata Atlântica," is described and illustrated. The new species belongs to Aristolochia subser. Hexandrae F. González. It is easily recognized by flowers that are slightly curved and have a long, spatulate, fimbriate limb, which is pale green on the inner surface. Aristolochia longispathulata is similar to A. arcuata and A. rumicifolia, from eastern and southeastern Brazil. Its floral morphology also resembles that of A. peltata, from the West Indies, and A. sessilifolia, from southern Brazil, Argentina, and Uruguay. /// Neste trabalho uma nova especie de Aristolochiaceae da Mata Atlântica, Bahia, Brasil, A. longispathulata, é descrita e illustrada. Esta espécie pertence a Aristolochia subser. Hexandrae F. González. E facilmente reconhecida por apresentar suas flores levemente curvadas, com o limbo longo, espatulado e fimbriado, além de possuir a face adaxial atipicamente alvo-esverdeada. Aristolochia longispathulata é semelhante a A. arcuata e A. rumicifolia, espécies da região oriental e sul-oriental do Brasil, embora a morfologia floral desta espécie assemelha-se a de A. peltata, das Indias Ocidentais, ou da espécie A. sessilifolia, do sul do Brasil, Argentina e Uruguai.
The developmental events in the periplasmic space and the cytoplasm of microspores of Magnolia sieboldii during microspore ontogeny have been traced with transmission electron microscopy in detail and compared to some developmental stages of other members of Magnoliaceae. We show that in mature pollen grains some important features, such as a columellate infratectum and a lamellate endexine, are not evident and highlight the importance of ontogenetic studies for the proper evaluation of exine structure. One of our aims was to find out whether the sequence of sporoderm developmental events represents the sequence of self-assembling micellar mesophases, the initiation of which is genetically controlled. Another aim was to consider substructural models of exine by John Rowley and his other chief ideas, and to analyse how these ideas concur with micellar hypotheses of exine development.
The recently published monograph of Aristolochiaceae for the Flora of Paraguay revives the traditional delimitation of Aristolochia with respect to the monotypic genera Euglypha y Holostylis. The presence of both morphological and molecular synapomorphies of Aristolochia in Euglypha and Holostylis, as well as the reevaluation of the diagnostic and differential traits of Euglypha and Holostylis, which are shown to be ambiguous, homoplasic, clinal or present only in late floral semaphoronts, provide conclusive evidence to subordinate E. rojasiana y H. reniformis in Aristolochia. The reconognition of Aristolochia, such as that followed in the mentioned monograph, implies the paraphyly of this taxon, which stands against the logic principles of the phylogenetic systematics. The morphological and molecular-based phylogenetic analyses of the Aristolochiaceae, which provide sufficient evidence to merge Euglypha and Holostylis within Aristolochia, as the first two laare nested in the clade formed by the subgenera Aristolochia + Pararistolochia, and more precisely within the New World subgenus Aristolochia sect. Gymnolobus.
Pollen ontogeny contributes significantly to the evolutionary analysis and the understanding of the reproductive biology of seed plants. Although much research on basal angiosperms is being carried out there are still many important features about which little is known in these taxa, such as the sporophytic structures related to pollen development and morphology. In this study, pollen development of Magnolia liliflora was analyzed by optical microscopy and transmission electron microscopy. The aim of this paper was to supply data that will help characterize basal angiosperms. Microsporogenesis is of the successive type, so that tetrads are decussate or isobilateral. The callosic walls form by the centripetal growth of furrows. The secretory tapetum develops orbicules, which start to form in the microspore tetrad stage. Pollen grains are shed at the bicellular stage. The exine wall has a granular infratectum. Ultrastructural changes observed in the cytoplasm of microspores and tapetal cells are related to the development of the pollen grain wall and orbicules. Centrifugal cell plates are more usual for the successive type of microsporogenesis. The presence of the successive type of microsporogenesis with callosic walls formed by the centripetal growth of furrows could reflect the fact that the successive type in Magnoliaceae is derived from the simultaneous type. The granular infratectum of the ectexine and the presence of orbicules could indicate that this species is one of the most evolved of the genus.
Microsporogenesis is highly labile in early-branching angiosperms, i.e., those with mostly sulcate pollen, compared with the tricolpate and tricolpate-derived eudicots. New records of microsporogenesis in basal angiosperms (19 taxa were examined), together with a review of the literature, demonstrate that the existing typology has been too strictly applied; several basal angiosperms have apparently intermediate forms and therefore do not fit easily into simultaneous or successive categories. Intermediate forms include the "modified simultaneous" type, where ephemeral cell plates are formed after the first meiotic division but then disperse, and simultaneous cleavage follows the second meiotic division. This relative diversity reflects a range of variation in number and position of pollen apertures in basal angiosperms, although both monosulcate and inaperturate pollen may occur in conjunction with either simultaneous or successive microsporogenesis. However, many taxa with inaperturate pollen have successive microsporogenesis, whereas many monosulcate taxa have the simultaneous type (although successive and monosulcate is common in monocotyledons). The predominance of simultaneous microsporogenesis in extant basal angiosperms and in land plants in general (including gymnosperms) indicates that simultaneous microsporogenesis is plesiomorphic in angiosperms, despite the occurrence of the successive type in the putative first-branching extant angiosperm, Amborella. This conclusion contradicts earlier views on the evolutionary polarity of this character.
The distribution of tapetal types in basal angiosperms is reviewed both from the literature and new observations in the context of recent phylogenetic analyses. Secretory tapeta predominate among land plants. The majority of basal angiosperms share a secretory tapetum with their anthophyte ancestors. Plasmodial and invasive tapeta are relatively rare in eudicots but have evolved several times among early-branching angiosperms, especially in monocotyledons, in which they have evolved three or more times. The invasive tapetum has evolved at least four other times independently in basal angiosperms: in Nymphaeaceae, Annonaceae, Monimiaceae, and Winteraceae. Plasmodial tapeta are mostly found in monocotyledons but have evolved at least twice in basal angiosperms, in Annonaceae, and in Hernandiaceae/Lauraceae. This apparent plasticity for a relatively brief but critical time in angiosperm evolution may reflect the early evolution of highly specific pollination syndromes.
Aristolochiaceae, a family of worldwide distribution comprising about 500 species, is a member of Piperales. Although Piperales is clearly monophyletic, the precise relationship within the order is ambiguous due to inconsistent placement of Lactoris fernandeziana. The appearance in some studies of Lactoris within Aristolochiaceae and the incongruence in generic treatments have also raised questions about the infrastructure of the family. This study addresses the overall generic relationships in Aristolochiaceae and its position in Piperales based on dense taxon sampling and sequence data from the plastid trnL-F region. The study resolved Piperales consisting of two major clades (Piperaceae plus Saururaceae and Lactoridaceae plus Aristolochiaceae) and Lactoris nested within Aristolochiaceae but with low support. The concept of two subfamilies in Aristolochiaceae, Asaroideae and Aristolochioideae, gains maximum statistical support. A generic treatment of Aristolochiaceae based on trnL-F is proposed which is congruent with recent analyses based on morphological characters.
The genus Aristolochia presents conserved features in its basic structural plan of trap flowers and in its pollination syndrome. Visitors, usually flies, are attracted to the rotting-meat scented flowers and remain trapped until the second day, when the protogynous flowers release them. Aristolochia gigantea Mart. and Zucc showed many of these floral traits but display a citronella-like odour, giving the opportunity to study the reproductive ecology in this atypical species. Characteristics and behavior of pollinators, coupled with the distances between individual plants and populations, are important factors in patterns of genetic diversity. Thus, our objectives were to study the flower visitors, reproductive success, and gene flow in A. gigantea in the Chapada Diamantina, Bahia, Brazil. Results suggest that pollination by flies remains as a conserved interaction within the genus Aristolochia. The main pollinators appeared to be Megaselia spp. (Phoridae), evidenced primarily by the frequency of their occurrence within flowers and the transference of compatible pollen. On the other hand, the moderate to low levels of intrapopulation genetic variability found in A. gigantea, combined with low effective pollination and its reproductive dependence on biotic vectors, indicate that this species may be suffering gene erosion in the remaining populations located at Chapada Diamantina.
A combined phylogenetic analysis of the Aristolochioideae was conducted based on 72 morphological characters and molecular data sets (matK gene, trnK intron, trnL intron, trnL-trnF spacer). The analysis sampled 33 species as the ingroup, including two species of Thottea, 30 species of Aristolochia, and the monotypic genus Euglypha, which represent all the infrageneric taxa formally described; Saruma henryi and Asarum caudatum were used as the outgroup. The results corroborate a sister-group relationship between Thottea and Aristolochia and the paraphyly of Aristolochia with respect to Euglypha, which consequently should be included in Aristolochia. Two of the three subgenera within Aristolochia (Isotrema and Pararistolochia) are shown to be monophyletic, whereas the signal obtained from the different data sets about the relationships within subgenus Aristolochia is low and conflicting, resulting in collapsed or unsupported branches. The relationship between the New World and the Old World species of subgenus Aristolochia is conflictive because morphological data support these two groups as monophyletic, whereas molecular data show the monophyletic Old World species of Aristolochia nested within the New World species. A sister-group relationship is proposed between Aristolochia lindneri and pentandrous species, which suggests that a group of five species from central and southern South America (including A. lindneri) could be monophyletic and sister to Aristolochia subsect. Pentandrae, a monophyletic taxon consisting of ca. 35 species from the southern United States, Mesoamerica, and the West Indies.
Two oppositely directed processes — uptake and secretion — occur probably simultaneously at the cell surface of a young tetrad microspore in Anaxagorea brevipes. Spiral elements, being the structural units of the microspore glycocalyx, are also seen in the tapetal cell glycocalyx, associated with the pro-orbicules. The glycocalyx spiral elements are connected with the cytoskeleton during the tetrad period. The sporopollenin precursor accumulations become evident at the middle tetrad stage as dark roundish particles. They are associated with the tops of the spiral elements and are the beginning of the protectum. Later sporopollenin precursor particles fuse with each other, resulting in a continuous, unbroken tectum. The granular infratectum is initiated at the late tetrad stage, the granules are also connected with the glycocalyx spiral elements but do not fuse with each other during the further development. The uneven foot layer of the ectexine forms at the early post-tetrad stage on the surface of the primordial lamella. The lamellated endexine forms at the middle post-tetrad stage. The distal aperture region lacks the infratectum and foot layer. The intine consists of two layers, the inner one is channelled. At the early tetrad stage, the secretory tapetum attempts to invade between the tetrads, but fails. The tapetum secretes orbicules and dark globular concretions.Several points are discussed: (1) the connection between the substructural exine units and the cytoskeleton; (2) the native form of sporopollenin precursor particles and its significance for phylogeny and ontogenetic structure-formative processes; (3) the existence of the endexine in primitive angiosperms, the problem of homologies in palynology; (5) the behaviour of the tapetum; and (6) the hypothetical possibility of the relationships between form and function.
Background and aims – Orbicules or Ubisch bodies have been recorded in many angiosperm families and although the first observations date back to 1865, their function in the anther remains enigmatic. In flowering plants a general evolutionary trend is observed from common
occurrence of orbicules in early diverging lineages towards a more patchy distribution in derived clades of eudicots. Annonaceae was our family of choice for an in depth study of orbicule distribution in early diverging angiosperms since it met the following three criteria: (1) high tapetum
diversity, (2) orbicule presence and absence recorded, and (3) recent phylogeny at genus level available.
Key results – Our SEM data of eighteen species show that orbicules are more common in Annonaceae than previously perceived. The resulting orbicule distribution pattern
on the family topology indicates a consistent absence of orbicules in the 'long branch clade' while orbicules are present in Anaxagorea, the ambavioids, and the 'short branch clade'. Presence of orbicules is the ancestral condition in the family. Morphologically, Annonaceae orbicules
are small (< 1 μm), spherical and smooth.
Conclusions – The orbicule distribution pattern in Annonaceae reflects the general evolutionary trend in flowering plants. We hypothesize that orbicule presence can be considered as a powerful proxy for non-amoeboid tapetum characterization
in Annonaceae.
The function of orbicules has been a matter of speculation for a long time and until now no satisfactory answer has been put forward. We propose two hypotheses that could contribute to the elucidation of their function: (1) that anemophilous and 'buzz pollination' species have microechinate orbicules and (2) that microechinate orbicules are advantageous for pollen release in both pollination modes. To test the first hypothesis, orbicule morphology of species in which the pollen is released by anther shaking (20 anemophilous and three with buzz-pollination) was analysed. We also conducted a literature review, noting the orbicule surface type and the presence of floral traits suggesting that pollen is released by anther shaking. Ninety-two percent of the species with microechinate orbicules are anemophilous or present 'buzz pollination'. Orbicules without spinules are present in species that lack floral traits linked to anther shaking for pollen release. To test the second hypothesis, a computational simulation that reveals the electric field produced by electrostatically charged orbicules was used. Results showed that the field is increased at the tip of each orbicule spinule. Therefore, an anther loculus surface coated by pointed structures increases the repulsion force of the pollen grains. This is an advantage when pollen is released by shaking the anther.
An update of the Angiosperm Phylogeny Group (APG) classification of the orders and families of angiosperms is presented. Several new orders are recognized: Boraginales, Dilleniales, Icacinales, Metteniusiales and Vahliales. This brings the total number of orders and families recognized in the APG system to 64 and 416, respectively. We propose two additional informal major clades, superrosids and superasterids, that each comprise the additional orders that are included in the larger clades dominated by the rosids and asterids. Families that made up potentially monofamilial orders, Dasypogonaceae and Sabiaceae, are instead referred to Arecales and Proteales, respectively. Two parasitic families formerly of uncertain positions are now placed: Cynomoriaceae in Saxifragales and Apodanthaceae in Cucurbitales. Although there is evidence that some families recognized in APG III are not monophyletic, we make no changes in Dioscoreales and Santalales relative to APG III and leave some genera in Lamiales unplaced (e.g. Peltanthera). These changes in familial circumscription and recognition have all resulted from new results published since APG III, except for some changes simply due to nomenclatural issues, which include substituting Asphodelaceae for Xanthorrhoeaceae (Asparagales) and Francoaceae for Melianthaceae (Geraniales); however, in Francoaceae we also include Bersamaceae, Ledocarpaceae, Rhynchothecaceae and Vivianiaceae. Other changes to family limits are not drastic or numerous and are mostly focused on some members of the lamiids, especially the former Icacinaceae that have long been problematic with several genera moved to the formerly monogeneric Metteniusaceae, but minor changes in circumscription include Aristolochiaceae (now including Lactoridaceae and Hydnoraceae; Aristolochiales), Maundiaceae (removed from Juncaginaceae; Alismatales), Restionaceae (now re-including Anarthriaceae and Centrolepidaceae; Poales), Buxaceae (now including Haptanthaceae; Buxales), Peraceae (split from Euphorbiaceae; Malpighiales), recognition of Petenaeaceae (Huerteales), Kewaceae, Limeaceae, Macarthuriaceae and Microteaceae (all Caryophyllales), Petiveriaceae split from Phytolaccaceae (Caryophyllales), changes to the generic composition of Ixonanthaceae and Irvingiaceae (with transfer of Allantospermum from the former to the latter; Malpighiales), transfer of Pakaraimaea (formerly Dipterocarpaceae) to Cistaceae (Malvales), transfer of Borthwickia, Forchhammeria, Stixis and Tirania (formerly all Capparaceae) to Resedaceae (Brassicales), Nyssaceae split from Cornaceae (Cornales), Pteleocarpa moved to Gelsemiaceae (Gentianales), changes to the generic composition of Gesneriaceae (Sanango moved from Loganiaceae) and Orobanchaceae (now including Lindenbergiaceae and Rehmanniaceae) and recognition of Mazaceae distinct from Phrymaceae (all Lamiales).
Pollen morphology of three genera representing 6 species of the family Dipsacaceae from Pakistan has been examined by light and scanning electron microscope. Pollen grains usually radially symmetrical, isopolar, mostly prolate-spheroidal rarely spheroidal, porate or tricolpate, sexine thicker or thinner than nexine. Tectal surface mostly spinulose rarely scabrate. On the basis of apertural types 3 distinct pollen types are recognized, viz.,Dipsacus inermis-type, Pterocephalus gedrosiacus-type and Scabiosa candollei-type.
The purpose of this study was to investigate the sporoderm development of inaperturate pollen grains
in Aristolochia clematitis (Aristolochiaceae). During successive microsporogenesis several types of tetrads
are formed; no tetrahedral tetrads were observed. In the tetrad period, the primexine is observed around the
perimeter of microspores. In the free microspore period, a thick lamellar endexine develops around the perimeter
of the microspore; the thick tubular intine appears later in this period. At the maturation of pollen grains, the
intine is stratified into two layers: an outer tubular ectintine and an inner homogeneous endintine. Finally, the
intine forms an aperture thickening. The thickened intine deforms and displaces the endexine and tears the
ectexine apart. This shows that pollen grains of A. clematitis are aperturate. The apertures are colpi.
Using comparative morphology studies from 123 species of Aristolochia sect. Gymnolobus subsect. Hexandrae, this taxon is reevaluated. Two series (Hexandrae and Thyrsicae, ser. nov.) and two subseries (Anthocaulicae, ser. nov., and Hexandrae) are recognized. Aristolochia (Thyrsicae) maxima and Aristolochia (Anthocaulicae) iquitensis are designated as types.
A study of the floral morphology and anatomy and pollen morphology of the monotypic Chinese genus Saruma was undertaken to provide a more thorough diagnosis of the plant and make comparisons with other members of the Aristolochiaceae. The possession of well-developed petals, a gynoecium of partially separate carpels, follicular fruit, and a monosulcate form of pollen document the primitive position of the genus. Pollen is semitectate and reticulate with a stratified, columellate wall structure. The gynoecium is of particular phylogenetic interest and is composed of a primitive form of three-trace carpel with an elongated, pubescent stigmatic region that extends along the exposed ventral (adaxial) surface. Numerous ovules are borne in two longitudinally oriented, submarginal rows and are vascularized by traces arising from the ventral bundles. The pattern of floral vascularization is similar to other members of the Aristolochiaceae, exhibiting the tendency for extensive fusion of vascular bundles. Unlike other Aristolochiaceae, oil cells and calcium oxalate crystals are absent from floral tissues. Saruma also diverges from the Aristolochiaceae by possessing stamens that become recurved inward at maturity, creating a functionally introrse dehiscence. Reproductive morphology provides compelling evidences for the segregation of Saruma to a distinct subfamily within the Aristolochiaceae. There is little convincing evidence to indicate that Saruma and Asarum share a common ancestry.
Aristolochia dalyi, from western Peruvian and Brazilian Amazonia, andA. bahiensis, from Bahia, Brazil, are described and illustrated. The species belong toAristolochia ser.Thyrsicae andA. ser.Hexandrae subser.Anthocaulicae, respectively. A key to the eight western Amazonian species of the seriesThyrsicae is presented.Aristolochia dalyi closely resemblesA. silvatica Barb. Rodr. from the Río Negro basin, andA. bahiensis—the first cauliflorous species ofAristolochia known from the Mata Atlantica—is similar toA. guentheri O. C. Schmidt andA. klugii O. C. Schmidt, from the Western Amazon basin. Characters based primarily on the perianth shape, along with some vegetative
features, are used to distinguish the two newly described species from their close relatives.
Within Aristolochiaceae, a secretory tapetum and orbicules are ubiquitous, but both simultaneous and successive types of microsporogenesis occur. Simultaneous cytokinesis is apparently plesiomorphic within the order Piperales, in which Aristolochiaceae are now placed. Successive microsporogenesis was found only in species of Aristolochia confined to a crown clade in the proposed phylogeny of this genus. In contrast to many other taxa, within Aristolochiaceae there is no strict relationship between microsporogenesis type and tetrad configuration, which is strongly influenced by spindle orientation, especially during meiosis II. There is also no direct correlation between microsporogenesis type and the aperture of mature pollen grains.
The glossary of pollen and spore terminology was first presented to the international palynological community as the final outcome of the Working Group on Palynological Terminology at the 8th International Palynological Congress in Aix-en-Provence in 1992. It became widely accepted as reference guide for palynologists to assist in the preparation of accurate and consistent descriptions of their material. It also serves as a practical source of information for non-specialists who wish to understand the meaning of the large number of existing palynological terms.The history of the glossary began in 1972 at the 3rd IPC at Novosibirsk when the working group on palynology was established. Throughout its history the project has been a collaborative effort with contributions from many palynologists, representing all branches of the discipline. Only through this long and elaborate procedure, with input from many people, it has been possible to produce the glossary.The entries are arranged alphabetically and are accompanied by simple schematic illustrations where appropriate. These contain the minimum amount of information needed to explain the feature. Moreover, to simplify the recognition of pollen and spore wall layers, colours have been used to indicate the corresponding layers.The first edition had 547 terms of which 339 have been accepted and recommended for use. In the second edition, a further 41 terms have been added with their appropriate illustrations. Of these, 10 have been accepted and 31 rejected for a variety of reasons. Where necessary, illustrations have been revised. An extensive list of consulted literature has been added.
Piperales represent the largest basal angiosperm order with a nearly worldwide distribution. The order includes three species rich genera, Piper (ca. 2000 species), Peperomia (ca. 1500-1700 species), and Aristolochia s. l. (ca. 500 species). Sequences of the matK gene and the non-coding trnK group II intron are analysed for a dense set of 105 taxa representing all families (except Hydnoraceae) and all generic segregates (except Euglypha within Aristolochiaceae) of Piperales. A large number of highly informative indels are found in the Piperales trnK/matK dataset. Within a narrow region approximately 500 nt downstream in the matK coding region (CDS), a length variable simple sequence repeat (SSR) expansion segment occurs, in which insertions and deletions have led to short frame-shifts. These are corrected shortly afterwards, resulting in a maximum of six amino acids being affected. Furthermore, additional non-functional matK copies were found in Zippelia begoniifolia, which can easily be discriminated from the functional open reading frame (ORF). The trnK/matK sequence data fully resolve relationships within Peperomia, whereas they are not effective within Piper. The resolution contrast is correlated with the rate heterogeneity between those lineages. Parsimony, Bayesian and likelihood analyses result in virtually the same topology, and converge on the monophyly of Piperaceae and Saururaceae. Lactoris gains high support as sister to Aristolochiaceae subf. Aristolochioideae, but the different tree inference methods yield conflicting results with respect to the relationships of subfam. Asaroideae. In Piperaceae, a clade formed by the monotypic genus Zippelia and the small genus Manekia (=Sarcorhachis) is sister to the two large genera Piper and Peperomia.
Pollen morphology of some primitive angiosperms
- V S Agababian
Agababian, V. S. (1969). Pollen morphology of some primitive angiosperms. V. Biologicheskii Zhurnal Armenii, 22, 54-66.
Aristolochiaceae in Flora do Brasil 2020
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Freitas, J., Lírio, E. J., Barros, F., & González, F. (2020). Aristolochiaceae in Flora do Brasil 2020. Jardim
Botânico do Rio de Janeiro. Rio de Janeiro (RJ). https://doi.org/10.47871/jbrj2021004.
Hacia una filogenia de Aristolochia y sus congéneres neotropicales. Caldasia
- F González
González, F. (1997). Hacia una filogenia de Aristolochia y sus congéneres neotropicales. Caldasia, 19(1-2),
115-130.
Aristolochia tricaudata . PalDat -A palynological database
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Halbritter, H. (2016b). Aristolochia tricaudata. PalDat -A palynological database. Retrieved from https://www.paldat.org/pub/Aristolochia tricaudata/302031.
Aristolochia arborea . PalDat -A palynological database
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Halbritter, H., Weber, M., Buchner, R., & Schneider, H. (2016).Aristolochia arborea. PalDat -A palynological
database. Retrieved from https://www.paldat.org/pub/Aristolochia arborea/301871.
Pollen and spores of plants from the flora of European part of the USSR
- L A Kuprianova
- L A Alyoshina
Kuprianova, L. A., & Alyoshina, L. A. (1972). Pollen and spores of plants from the flora of European part
of the USSR: I. Nauka, S.-Pb.
Molecular phylogeny and comparative pollen morphology of the genus Hexastylis (Aristolochiaceae)
- B A Niedenberger
Niedenberger, B. A. (2010). Molecular phylogeny and comparative pollen morphology of the genus Hexastylis
(Aristolochiaceae). Master's thesis. Appalachian State University, Boone, North Carolina.
Molecular phylogeny of Aristolochia sensu lato (Aristolochiaceae) based on sequences of rbcL, matK, and phyA genes, with special reference to differentiation of chromosome numbers
- T Ohi-Toma
- T Sugawara
- H Murata
- S Wanke
- C Neinhuis
- J Murata
Ohi-Toma, T., Sugawara, T., Murata, H., Wanke, S., Neinhuis, C., & Murata, J. (2006). Molecular phylogeny of Aristolochia sensu lato (Aristolochiaceae) based on sequences of rbcL, matK, and phyA genes, with special reference to differentiation of chromosome numbers.Systematic Botany, 31, 481-492.
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Index Herbariorum: A global directory of public herbaria and associated staff
- B Thiers
Thiers, B. 2023. Index Herbariorum: A global directory of public herbaria and associated staff. New York
Botanical Garden's Virtual Herbarium. Retrieved from https://sweetgum.nybg.org/ih/.