Article

Comparative anatomy and morphology of fertile complexes of Prumnopitys and Afrocarpus species (Podocarpaceae) as revealed by histology and NMR imaging, and their relevance to systematics

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Abstract

Fertile complexes (individual reproductive units of ovulate cones) of three Prumnopitys species and Afrocarpus falcatus (Podocarpaceae) were subjected to histological examination and non-destructive NMR imaging. The latter technique allowed the display, frame-by-frame analysis and electronic ‘dissection’ of internal structures such as the number and courses of vascular traces and resin canals and their morphology. Characters of these internal structures distinguished all three Prumnopitys species from each other and thus were shown to be taxonomically diagnostic. Fertile complexes of Prumnopitys andina and P. taxifolia were most similar, possessing simple vascular traces and few unbranched resin canals. Those of P. ferruginea were very different and possessed an interconnected network of resin ducts within the sarcotesta. These findings are congruent with relationships inferred from molecular phylogenetic studies, in which two subclades were recovered within Prumnopitys. The anatomy of the female fertile complexes of Afrocarpus falcatus was very distinct from all Prumnopitys species analysed. Its most distinctive feature was the existence of a complex network of radial vascular strands originating from within the outer layers of the sarcotesta and penetrating the inner layers of the fertile complex. The surface texture and morphology of the sclerotesta of the seed was also unique to each species. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 145, 295–316.

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... Microcachrys and Saxegothaea have multiseeded cones, which are fleshy with whorled ovuliferous complexes (OCs) for Microcachrys and coriaceous with helically arranged OCs for Saxegothaea (Thomson 1909;Florin 1951;Farjon 2010). Some genera, such as Prumnopitys, Phyllocladus, and Lagarostrobos, show wide ranges in the number of seeds per cone (Molloy 1995;Farjon 2010), but most genera have one or two seeds per cone and show diverse structural adaptations that have been related to zoochory (Pilger 1903;Sahni and Mitra 1927;Tomlinson 1992;Mill et al. 2004). Such adaptations include the different degrees of development and fleshiness of the epimatium and the presence/absence of a fleshy receptacle. ...
... The receptacle (or podocarpium) is a structure that is interpreted to result from the fusion of the basal vestigial OCs of the cone (and occasionally the bract of the fertile complex) and that becomes fleshy as the cone matures (Del Fueyo 1999;Mill et al. 2001). Additionally, the mature seed can be erect (e.g., Manoao; Molloy 1995), oblique (e.g., Acmopyle; Sahni 1920;Mill et al. 2001), or inverted (e.g., Prumnopitys; Mill et al. 2004), depending on the degree of development of the epimatium (Tomlinson 1992). ...
... The tropical clade includes 11 genera, ca. 88% of the species diversity of the family (following Farjon 2010), and contains the most emblematic and wellknown genera of Podocarpaceae (Thomson 1909;Gibbs 1912;Sinnott 1913;Sahni 1920;Schoonraad and van der Schijff 1974;Tomlinson 1992;Del Fueyo 1999;Glidewell et al. 2001;Mill et al. 2001Mill et al. , 2004Restemeyer 2002;Tomlinson and Takaso 2002;Khan and Hill 2021). The prumnopityoid clade includes the remaining less explored taxa (e.g., Sahni and Mitra 1927;Khan et al. 2022) and presents little consensus in the resolution of internal relationships (Andruchow-Colombo et al. 2019a;Sudianto et al. 2019). ...
... The Podocarpaceae have an amazing diversity of seed cone morphology and possess different morphotypes across all major clades. Several studies have investigated seed cone evolution in conifers (Tomlinson, 1992;Mundry, 2000;Restemeyer, 2002;Mill et al., 2004;Klaus and Matzke, 2020). Klaus and Matzke (2020) reported that the ancestral seed cones in Podocarpaceae were non-fleshy, and fleshy cone structures appeared seven times independently in podocarps. ...
... Prumnopitys subgenus Prumnopitys has multiovulate cones (P. andina has about 4-12 seeds and P. taxifolia about 5-10 seeds; see also Mill et al., 2004). ...
... When the epimatium is fused with the testa it is either fleshy or papery, forming a sarcotesta-like seed coat (Fig. 6), such as in Parasitaxus, Pectinopitys, Prumnopitys and Sundacarpus, and this also occurs in Retrophyllum, Afrocarpus and some species of Podocarpus (i.e. P. smithii, P. henkelii, P. madagascariensis and P. capuronii) in the Podocarpoid clade (Mill et al., 2001(Mill et al., , 2004Khan and Hill, 2021). ...
Article
Background and Aims Seed cone traits are significant for understanding the evolutionary history of conifers. Podocarpaceae has fleshy cones with a distinct morphology compared to other conifers. However, we have a poor understanding of the seed cone morphology of the Prumnopityoid clade within Podocarpaceae. This study presents detailed seed cone morpho-anatomy and the evolution of fleshy structures and traits in the Prumnopityoid clade. Methods We investigated the detailed seed cone morpho-anatomy of selected species from the nine genera using the histological method. The evolution of morpho-anatomical traits was assessed using ancestral state reconstruction methods. Key Results The Prumnopityoid clade has evolved fleshy seed cones using different functional structures (e.g. aril, epimatium, bracts or receptaculum) and fleshiness is an ancestral trait in the clade. An epimatium is present in all genera except Phyllocladus, but with different structural morphologies (e.g. a fleshy asymmetrical cup-like epimatium or an epimatium that is fused with the integument forming a fleshy sarcotesta-like seed coat). In all species with fleshy sarcotesta-like seed coats, the endotesta is hard and woody, forming a sclerotesta-like structure and the epimatium and exotesta are fused, forming a fleshy sarcotesta-like structure. Conclusions This study highlights that the Prumnopityoid clade has an amazing diversity of structures and complex evolutionary patterns. Fleshiness is an ancestral trait of the clade and has been achieved via diverse evolutionary pathways and structures. This clade has four distinct seed cone types i.e. drupe-like, receptaculate, arilloid and dacrydioid cones based on morpho-anatomical structures and traits. The macrofossil record also demonstrates the presence of several structures and traits.
... The Dacrydioid clade is the second most species-rich clade and includes three genera (Dacrydium, Dacrycarpus and Falcatifolium) with a suggested crown age of approximately 75 Ma and is predominantly distributed in the Southern Hemisphere [4,13]. Some studies have evaluated seed cone evolution in conifers based on morpho-anatomy, and some have used model-based ancestral reconstruction [6,8,14,[16][17][18][19]. However, detailed and comprehensive studies of the seed cone morpho-anatomy are still lacking. ...
... The study by Chen et al. [19] considers the epimatium of Dacrydium, Falcatifolium, Microcachrys and Lepidothamnus as non-fleshy and reported a complete absence of fleshy receptacles in Nageia in their ancestral reconstructions. Although some studies have been undertaken to evaluate different aspects of the reproductive cycles of Acmopyle, Podocarpus, Dacrydium and Dacrycarpus [14,[16][17][18], no comprehensive studies are available on detailed seed cone morpho-anatomy and the evolution of functional traits and structures for both the Podocarpoid and Dacrydioid clades. Similarly, because seed cone morphology is complex in podocarps and there has been a lack of detailed studies on the seed cone morpho-anatomy, it is difficult to correlate fossil seed cones with extant taxa [4]. ...
Article
The study of reproductive morphology and trait evolution provides a vital insight to understand the evolutionary history of plants. The conifer family Podocarpaceae has a remarkable diversity of seed cones, with distinct morphology among the genera and with conifers in general. However, we lack a good understanding of the seed cone morpho-anatomy and trait evolution of Podocarpaceae. We investigated detailed seed cone morpho-anatomy using staining and sectioning techniques to clarify the anatomical, morphological diversity and evolution of functional traits. The presence of a fleshy receptaculum is a characteristic feature of both clades. However, species of Retrophyllum, Afrocarpus and some species of Nageia and Podocarpus form a fleshy sarcotesta-like seed coat, lacking a fleshy receptaculum. The ancestral state reconstructions show a shift between and sometimes within the genus. Although both clades demonstrate fleshiness as an ancestral trait, the shift in fleshy structures provides evidence for complex multiple evolutions of fleshy morphologies. These seed cone traits (e.g., fleshiness and size), along with the broad, flattened and well-adapted (leaf dimorphism) foliage in both clades, are largely congruent with efficient light harvesting and bird dispersal. These traits make these two clades well adapted to their environment, when growing in communities including tall and broad-leaved angiosperms (closed-canopy angiosperm forests), compared to other podocarps, making them more successful in achieving a wider distribution and species richness.
... B, Consensus network with a 20% cut-off of the sampled trees obtained in the Bayesian analysis. 1995, Farjon 2017), show different degrees of development and fleshiness of the epimatium (from absent in Pherosphaera to fully covering and extending beyond the seed micropyle in Halocarpus, Sahni and Mitra 1927), and the presence/absence of a fleshy receptacle (Sahni and Mitra 1927, Tomlinson 1992, Mill et al. 2004). The epimatium is interpreted to be homologous to the conifer ovuliferous scale (Sinnott 1913, Tomlinson 1992, Englund et al. 2011, which is highly modified in most podocarps. ...
... The Jurassic record of Podocarpaceae is not extensive but contains the first unambiguous records of vegetative and reproductive organs, and thus crucial data on early trait configurations. Jurassic seed cones are lax and multi-ovulate (Harris 1979, Reymanówna 1987, implying cone reduction, associated with bird dispersal, had not yet occurred (Pilger 1903, Sahni and Mitra 1927, Tomlinson 1992, Mill et al. 2004. However, isolated ovuliferous complexes (Reymanówna 1987, García Massini et al. 2016 suggest they may have functioned as diaspores like in modern taxa (Contreras et al. 2017, Klaus andMatzke 2019). ...
Article
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The Podocarpaceae are a morphologically diverse conifer family that have a cryptic fossil record reported since the Permian. We reviewed the fossil record of Podocarpaceae, tested the affinities of its oldest records using phylogenetic analyses, compiled macrofossil occurrence records, and investigated the diversity, distribution, and morphology of Podocarpaceae through time. We found that Permian, Triassic, and some Jurassic fossils referred to Podocarpaceae should not be placed in the family. Our total-evidence phylogenetic analyses, which sampled all major conifer lineages, recovered the Triassic Rissikia and the Jurassic Nothodacrium as stem-group conifers and the Jurassic Mataia as part of the Araucariales stem group. We further discuss the phylogenetic position of the Mesozoic enigmatic conifers Pararaucaria (Cheirolepidiaceae) and Telemachus (Voltziales), which were recovered most frequently in the conifer stem group. We conclude that the earliest reliable Podocarpaceae occurrences are from the Jurassic of both hemispheres and have scale-like leaves. Most extant genera appear in the fossil record between the Late Cretaceous and the Early Cenozoic. Many extant leaf morphologies appear in the Early Cretaceous, coeval with angiosperm diversification, consistent with the hypothesis that expanded leaves in Podocarpaceae are adaptive responses for light harvesting in angiosperm-dominated environments today.
... The family Araucariaceae (Araucariales) has archaeophylls (Fig. 11.14) or single veined needles. The compound cones of the family Podocarpaceae from the same order are reduced to a few seed scales fused with bracts (Tomlinson 1992;Mill et al. 2004). The fossil genus Rissikistrobus (Fig. 11.15) had these simplified cones arranged in a bicompound cone whereas recent genera have these simplified cones fleshy (Fig. 11.16). ...
... The sarcotesta was common in early conifers and it is present even in recent Podocarpaceae, where the sarcotesta with fleshy seed scales forms the epimatium (Tomlinson 1992). And in that case, the aril is clearly differentiated into an outer fleshy layer and the inner fleshy sarcotesta (Mill et al. 2004). The compound male strobili (Fig. 11.22) are arranged into bicompound strobilus, subtended by bracts. ...
Article
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The previous theory about the origin of microphyllous and megaphyllous leaves can also be applied to seed plants. The existence of a microphyll of archaeophyll type offers new perspectives on the ovule origin. There are various phylogenetic classifications of gymnosperms. This paper brings new morphological insights on these classifications and recognizes three morphological groups of gymnosperms-primary cupulate and primary acupulate megaphyllous lineages and strobilate microphyllous lineage. Evolution from these three groups could continue in various directions, therefore there are many morphological similarities among them leading to many phylogenetic interpretations. The taxonomic groups based on the antophyte theory would be polyphyletic according to new morphological interpretations because all types of gymnosperm strobili could lead to formation of flowers.
... The ability to make unobstructed observations of tissues and cells in three dimensions has long been an ambition of anatomists and histologists, and several methods have already been developed. Non-destructive bio-imaging methods, such as confocal imaging (Gray et al., 1999;Bougourd et al., 2000;Haseloff, 2003;Kitin et al., 2003;Wegel et al., 2005;Buda et al., 2009), optical projection tomography (Lee et al., 2006), X-ray techniques (Stuppy et al., 2003), and nuclear magnetic resonance imaging (Glidewell et al., 1999;Ishida et al., 2000;Mill et al., 2004;Glidewell, 2006), have been successfully applied to generate three-dimensional (3D) images of plant organs and tissues. ...
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Premise Previously we described methods for generating three‐dimensional (3D) virtual reconstructions of plant tissues from transverse thin sections. Here, we report the applicability of longitudinal sections and improved image‐processing steps that are simpler to perform and utilize free applications. Methods In order to obtain improved digital images and a virtual 3D object (cuboid), GIMP 2.10 and ImageJ 2.3.0 running on a laptop computer were used. Sectional views of the cuboid and 3D visualization were realized with use of the plug‐ins “Volume Viewer” and “3D Viewer” in ImageJ. Results A 3D object was constructed and sectional views along several cutting planes were generated. The 3D object consisted of selected tissues inside the cuboid that were extracted and visualized from the original section data, and an animated video of the 3D construct was also produced. Discussion Virtual cuboids can be constructed by stacking longitudinal images along the transverse depth direction or stacking transverse images vertically along the organ axis, with both generating similar 3D objects. Which to use depends on the purpose of the investigation: if the vertical cell structures need close examination, the former method may be better, but for more general spatial evaluations or for evaluation of organs over longer tissue distances than can be accommodated with longitudinal sectioning, the latter method should be chosen.
... For brevity they Plate I. Foliage and fruit of Prumnopitys andina are loosely referred to as 'fruits'. The olive green, fleshy tissue itself is referred to as `sarcotesta' (Mill et al., 2004) -believed to be fused integument plus epimatium epimatium only, of other podocarp fruits). Removal of this tissue (in a process we call de-pulping) revealed the equivalent of a cherry 'stone'. ...
Article
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Prumnopitys andina is a member of the Podocarpaceae native to Chile and Argentina. It is known to be relatively easy to propagate vegetatively, but germination from seeds is poor and can be spread over at least four years. This paper describes the methods that were used to raise 89 seedlings from 262 seeds (=34%) in less than 1 year. The sequence involves i) completely removing the fleshy sarcotesta; ii) thoroughly washing the seed-coat; iii) `pretreating' the imbibed seeds by incubating them in moist peat and sand at a daily alternating 10/15°C for several months (to allow 'maturation' or `after-ripening' / 'dormancy breakage' at present we do not know which); iv) carefully cracking the seed-coat in a vice and extracting the embryo; v) culturing clean, firm, healthy (=-`viable') embryos on moist filter paper at a daily alternating 20/30°C (with lights during the 30°C phase); [vi) where necessary, freeing the cotyledons of all seedlings that become trapped in the female gametophyte]; vii) transplanting seedlings to conventional nursery practice. A further 1008 seeds are continuing 'pretreatment' to investigate whether this will increase the proportion of seedlings per viable embryo or better still lead to a much less labour intensive seedling emergence from intact seeds.
... fleshy. Fruit details in Mill et al. (2004) frugivory (Givnish 1980 (Campbell 1968) wind, water, ballistic, testa reticulate and papery (Leake 1994, Yang et al. 2002 wind ?capsule Centrolepidaceae Centrolepis ciliata herb seed seed small, testa reticulate. ...
... The integument of ovules in the Podocarpaceae consists of a thick sclerified middle layer between two fleshy layers, with the inner one becoming membranous during maturation. Vascularization of the integument is highly variable within the family (Mill et al., 2004). ...
Article
A new anatomically preserved ovule is described from the Middle Triassic Fremouw Formation of the Beardmore Glacier area, Antarctica. Probolosperma antarcticum gen. et sp. nov. is bilaterally symmetrical and up to 1cm long and 6mm wide. The integument is characterized by a complex sarcotesta with a palisade-like outer layer and a sclerotesta that forms two small lateral wings and elaborations in the chalazal and apical regions. The vascular system consists of a terete strand that enters the pedicel to form a small cup of tracheids at the base of the nucellus, with two strands that extend distally in the inner part of the sclerotesta. Comparisons with other gymnosperm ovules indicate that Probolosperma represents a new taxon, which enhances the diversity of known seed plants from the Triassic of Antarctica.
... Non-destructive bio-imaging methods, such as high-resolution confocal imaging (Bougourd et al., 2000;Haseloff, 2003;Wegel et al., 2005), optical projection tomography (Lee et al., 2006), X-ray techniques (Stuppy et al., 2003), and nuclear magnetic resonance imaging (Glidewell et al., 1999(Glidewell et al., , 2002Ishida et al., 2000;Mill et al., 2004) have been successfully applied to generate 3D images of plant organs or tissues. Confocal microscopy produces high-resolution fluorescence images that allow cellular resolution, but sample depth is limited (Megason and Fraser, 2003;Streicher et al., 2000). ...
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Analysis of gene expression in the developing barley caryopsis requires effective instruments for visualization of the grain and the 3D expression patterns. Digital models of developing barley (Hordeum vulgare) grains were reconstructed from serial sections to visualize the complex three-dimensional (3D) grain anatomy, to generate and analyse 3D expression patterns, and to quantify tissues during growth. The models provide detailed spatial descriptions of developing grains at anthesis, at the syncytial stage of endosperm development and at the onset of starch accumulation, visualizing and quantifying 18 tissues or tissue complexes. Total caryopsis volumes and volume changes of specific tissues between the stages were determined, and proportions of ovule- and non-ovule-tissues and ratios of filial to maternal tissues were calculated from the model data. To generate and analyse 3D expression patterns, data from mRNA localization by in situ hybridizations were integrated into the models. At the onset of starch accumulation, cell-wall invertase (HvCWINV1) mRNA is mainly localized in the transfer cells and to a lesser degree in zones of the starchy endosperm. Using the model, an expression gradient across the grain was visualized. The expression pattern in the upper region of the caryopsis resembles that found in the median region at an earlier stage, indicating the presence of a developmental gradient. At anthesis, mRNA of the protease nucellin was visualized in a distinct zone of the nucellus near the antipodal cells.
Article
Scientific interest has grown over recent years in response to greatly increased perception of the phylogenetic diversity within the conifers as a whole. Much of this has been stimulated by perspectives of increased knowledge of depths of divisions amongst the many living member groupings, especially from DNA-molecular analyses. Interest includes increasing awareness of just how different and ancient have various of the coniferous divisions been, leading to long phylogenetic-autonomy for many components in major evolutionary developments, often with strong independencies across both Hemispheres. The mainly Southern Hemisphere podocarp members are emerging as one of the most diverse of overall arborescent gymnosperm groupings, and this diversity has been one which has spawned increasing interest in matching taxonomic status to phylogenetic perspectives emerging. Amongst these, the early phylogenetic divergences within the Sundacarpus-Prumnopitys alliance have become increasingly apparent. When combined with independent data from several other lines of evidence, a need for re-evaluation of the generic-boundaries within this group becomes necessary. A taxonomic revision is thus proposed here, separating a newly-named segregate genus, Pectinopitys, from the wider Prumnopitys s.l. alliance, as currently known. Consequent nomenclatural changes are given, and impact one of the species in New Zealand (where two genera here recognised are sympatric), plus those of the Australian region and several of those of the South American continent. Two fossil members from the Northern Hemisphere are also taken into account. On the above bases, main morphological features distinguishing Pectinopitys from Prumnopitys s.s. thus especially include, as ‘key’ main identity features, vegetative characters of leaf-type, spacing, insertion and arrangement.
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A cuticular micromorphological study confirms the separate generic status of Afrocarpus, Nageia and Retrophyllum and increases the number of available diagnostic characteristics. A re-investigation of fossil species previously assigned to this complex demonstrates that in all cases the generic designation was incorrect. Foliage characters which are now unique to Retrophyllum among the Podocarpaceae were once more widespread, providing further evidence for the hypothesis that many podocarpaceous taxa converged towards the production of flattened short shoots to increase photosynthetic efficiency. -from Authors
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Many taxonomic distinctions are made or refined on the basis of herbarium material that is either dried or preserved in spirit medium. Hitherto, examination of internal structure has only been possible by the destructive sectioning of the preserved material. In this paper, the use of nuclear magnetic resonance (NMR) imaging for the non-destructive, non-invasive, complete three-dimensional structural examination of herbarium material is demonstrated for the first time. The experimental materials were the fruiting structures of two species of Southern Hemisphere Podocarpaceae: Acmopyle pancheri and Podocarpus nivalis. Material dried in accordance with standard herbarium techniques was used, as well as material preserved in spirit and freshly gathered fruits. The dried material was subsequently rehydrated using standard techniques, and protocols established for the specimens. Appropriate selection of NMR imaging parameters allowed a variety of anatomical features to be highlighted on a single specimen. Fresh specimens from living material gave the best NMR signals. Dry specimens gave no signal except from the lipid in the seed, but when rehydrated the images yielded almost as much information about internal structure as did a fresh specimen of the same taxon. Thus, NMR imaging has great potential value as a non-invasive method for obtaining details of the internal structure of fruits and seeds and is particularly useful when, as in the case of Acmopyle, the sclerotesta of the seed is too lignified for sectioning by conventional methods.
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This paper summarizes the early history of the lysigenous gland concept, traces its evolution to recent times, and explores some possible causes of conflicting reports of lysigeny and schizogeny. Secretory cavities and ducts are generally thought to form either through the schizogenous separation of cells or through lysigeny (cell lysis). Gland lysigeny was first proposed in 1857 by Karsten, who believed that plant tissues represent solidifications of humoral fluids and that plant secretions are formed by the resorption of previously solidified cells. The lysigenous gland concept has modernized as our understanding of cytology has improved, but it was established early, from Karsten’s hypothesis, long before the influence of artifacts of specimen preparation was appreciated. Different methods of specimen preparation, including variations in the mounting media used to mount freehand sections, may have caused some of the discrepancies between the findings of lysigenists and schizogenists. Tschirch and Haberlandt promoted the schizolysigeny concept, and believed that the conflicting reports resulted from incomplete observations of a developmental process that included both schizogenous separation of cells and cell lysis to form secretory cavities and ducts. Both lysigeny and schizogeny have been reported in the recent literature, although most reports of lysigeny have been opposed by conflicting observations of schizogeny, and lysigeny may represent a false category of gland development caused by the misinterpretation of artifacts.
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The pollination mechanisms of Acmopyle pancheri(Brongn. & Gris) Pilg. andPhyllocladus hypophyllus Hook.f. were investigated by conventional microscopical techniques and by nuclear magnetic resonance (NMR) imaging. Dissimilarities include the orientation of the ovule and type of pollen;Phyllocladus has erect ovules and wettable pollen with vestigial sacci, whereas Acmopyle has more-or-less erect ovules and non-wettable, functionally saccate pollen. Similarities include the mode of formation of the pollination drop and its response upon pollination. In both genera, pollination triggers pollination drop retraction and drop secretion ceases. Neither NMR imaging nor conventional histology of Phyllocladus ovules revealed any specific tissue beneath the ovule which could be responsible for pollination drop retraction. It is more likely, therefore, that the drop is channelled into the vascular supply or the apoplast. These findings invalidate the taxonomic value of the pollination mechanism as a suite of characters traditionally used to separate Phyllocladaceae from Podocarpaceae. Copyright 2000 Annals of Botany Company
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The vascular system in the base of the vegetative axillary shoot, the axis of female cône and the epimatium in Stachycarpus spicata R. Br. (Podocarpacées) shows the same organisation: two initial trunks divided into sympodia; as a result the epimatium at the origin represents a reduced axillary shoot and the strobile corresponds to the inflorescential structure.
Chapter
Slightly resinous, dioecious or rarely monoecious, evergreen shrubs or trees. Leaves simple, entire, linear, often long-persistent, usually spirally arranged, highly variable in form, from large, linear, and flattened to scale-like, distant or crowded, spreading or swept forward, amphistomatic or hypostomatic, soft, flexible, occasionally leathery, rarely harsh; shoots glabrous. Male (pollen) cones catkin-like, solitary or clustered, terminal or axillary, each cylindric with numerous spirally arranged scales each bearing 2 pollen sacs. Pollen grains with two (occasionally three) air-bladders, rarely 0 (Saxegothaea). Female (ovuliferous) cones terminal or axillary, usually solitary, varying much in complexity between the genera, of one or many bracts, each or only one of each bearing one ovule, sometimes with several further fused, reduced bracts which are adnate to the rachis and form a basal peduncle (“receptacle”) which may be either dry or become fleshy and succulent after fertilization, ovules erect or asymmetrically inverted; the mature cones drupe-like or rarely cone-like or with a single (rarely paired), free, ovoid, protruding seed, which is sometimes surrounded by a fleshy false aril (“epimatium”) or dry and seated on an enlarged fleshy receptacle. Cotyledons 2.
Article
Arabidopsis inflorescence stems develop a vascular pattern similar to that found in most dicots. The arrangement of vascular tissues within the bundle is collateral, and vascular bundles in the stele are arranged in a ring. Although auxin has been shown to be an inducer of vascular differentiation, little is known about the molecular mechanisms controlling vascular pattern formation. By screening ethyl methanesufonate-mutagenized populations of Arabidopsis, we have isolated an avb1 (amphivasal vascular bundle) mutant with a novel vascular pattern. Unlike the collateral vascular bundles seen in the wild-type stems, the vascular bundles in the avb1 stems were similar to amphivasal bundles, i.e. the xylem completely surrounded the phloem. Furthermore, branching vascular bundles in the avb1 stems abnormally penetrated into the pith, which resulted in a disruption in the ring-like arrangement of vascular bundles in the stele. The avb1 mutation did not affect leaf venation pattern and root vascular organization. Auxin polar transport assay indicated that the avb1 mutation did not disrupt the auxin polar transport activity in inflorescence stems. The avb1 mutation also exhibited pleiotropic phenotypes, including curled stems and extra cauline branches. Genetic analysis indicated that the avb1 mutation was monogenic and partially dominant. The avb1 locus was mapped to a region between markers mi69 and ASB2, which is covered by a yeast artificial chromosome clone, CIC9E2, on chromosome 5. Isolation of the avb1 mutant provides a novel means to study the evolutionary mechanisms controlling the arrangement of vascular tissues within the bundle, as well as the mechanisms controlling the arrangement of vascular bundles in the stele.
Article
The Podocarpaceae are the most morphologically diverse of conifer families. A taxonomic trend has resulted in recognising this diversity via smaller generic groupings, including several monotypes. A phylogenetic assessment of the monotypic genera Sundacarpus and Manoao was conducted employing maximum parsimony the analysis of sequence data from 18S-ribosomal DNA from 34 gymnosperm taxa, including 29 Podocarpaceae. In resulting trees, there is high bootstrap support for Podocarpaceae, including Phyllocladus, but the order of deep branches within the family is equivocal. Prumnopitys (Sundacarpus) amara (Blume) de Laub. and four other Prumnopitys spp. comprise a clade with a bootstrap value of 100%, supporting the retention of Sundacarpus as a section of Prumnopitys. Lagarostrobos franklinii (Hook.f.) Quinn and L. (Manoao) colensoi (Hook.) Quinn comprise a clade with equivocal bootstrap support, echoing previous results from parsimony analysis of morphological data. A conservative approach (i.e. one avoiding unnecessary monotypes) favours the retention of L. colensoi in Lagarostrobos, pending further evidence of relationships within the group.
Article
Synopsis Two new species of petrified seeds Eosperma edromense , and Anasperma burnense gen. et sp. nov. are described from the Cementstone Group of Berwickshire. Anasperma shows that the anatropous condition existed among Palæozoic ovules; it has a single integument with two lateral apical lobes. Rachides of Stauropteris berwickensis sp. nov. and associated megasporangia are also described. An account is given of the theory of the telomic origin of the first ovular integument. The second (outer) integument in Angiosperm ovules may therefore have evolved after the establishment of anatropy, either from the first integument or as an overgrowth of the chalaza. Evidence is cited to support the theory that Angiosperm carpels have evolved from dorsiventral bivalved cupules.
Article
The developmental morphology and anatomy of the female cones of Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae) are described and illustrated, based on observations, histology, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) imaging. Ovulate development is typically podocarpaceous. Ovules are unitegmic, and horizontal or inclined upwards throughout ontogeny; the pollination drop is inverted because of the declinate micropyle. Ontogeny of the epimatium-ovule complex is acropetal, the epimatium developing first. A terminal, distal sterile bract creates a pollen-scavenging area. During development, the whole cone re-orientates through some 270°, and the seed realigns approx. 60° with respect to the receptacle axis. The ‘receptacle’ or podocarpium supporting the seed is formed by gradual fusion of initially free bracts. The structures adnate to these bracts represent homologues of ovuliferous scales; they bear vestigial epimatia which may develop into supernumerary ovules or non-functional epimatia. Thus, female cones ofA. pancheri are vestigially multi-ovulate. NMR imaging effectively and non-invasively revealed the three-dimensional arrangement of vascular bundles and resin canals in the cones. Copyright 2001 Annals of Botany Company
Article
Summary • Nuclear magnetic resonance (NMR) imaging was investigated as a tool for the detailed morphological comparison of two species of Podocarpaceae of taxonomic interest; these were difficult to investigate by conventional methods. • Two- and three-dimensional NMR images of female cones of Afrocarpus falcatus and Prumnopitys ferruginea were acquired using a range of protocols. Conventional sectioning and microscopic techniques and low-temperature scanning electron microscopy were used where possible, to corroborate the assignments of the NMR images. • A three-dimensional network of resin canals in Prumnopitys ferruginea was revealed and the presence of resin confirmed by chemical shift imaging. Similar canals in cones of Afrocarpus falcatus did not contain resin but the presence of spoke-like vascular traces passing through the sclerotesta was demonstrated. Marked differences in the structure of the sarcotesta of the two species were readily discernible. • NMR imaging allowed noninvasive retrieval of both internal morphological and histochemical information from single specimens in their natural state in a much shorter time than conventional methods would allow and provides useful data for taxonomic purposes in the Podocarpaceae.
Article
The distribution of saccate and nonsaccate pollen in modem conifers (nomenclature after Page 1990) shows a correlation with the method of pollen capture by the micropyle, although this has been little emphasized. Saccate pollen is restricted to, but not ubiquitous in, Phyllocladaceae, Pinaceae, and Podocarpaceae and is associated with the development of an inverted pollination drop, except in Phyllocladus. Saccate pollen is also nonwettable, in the sense that it floats on water, and it functions as a distinctive antigravity device. Pollen entry into the micropyle is dependent on resorption of the pollination drop and selectively excludes foreign particles. Nonsaccate pollen is wettable and sinks in water, but with two contrasted behaviors that discriminate two types of pollen reception. In Cephalotaxaceae, Cupressaceae, Sciadopityaceae, Taxaceae, and Taxodiaceae there is a pollination drop without preferred orientation. Pollen swells and bursts in water, shedding the exine by a mechanism determined by the apparently simple wall structure. In the remaining conifers with nonsaccate pollen-Agathis, Araucaria, i.e., Araucariaceae, together with Larix, Pseudotsuga, and Tsuga (Pinaceae) and Saxegothaea (Podocarpaceae)-there is no pollination drop, pollen is wettable but does not burst in water, and there is either extended siphonogamy or micropylar invagination. These observations show the adaptive features of pollen structure and ultrastructure. Despite their ubiquitous wind pollination, conifers thus have some diversity of pollination syndromes with reference to water and the introduction of pollen into the pollen chamber of the ovule, at which time pollination is complete.
Article
Ovulate cones in most Podocarpaceae consist of one or more fertile units, each composed of a fertile bract subtending an axillary epimatium that supports a single adaxial inverted ovule. Cones may consist of numerous units, up to ca. 20 in Microcachrys, but show progressive reduction in different taxa to the ultimate condition in which there is only a single pseudoterminal ovular unit. In the development of the ovular complex the solitary ovule arises from the surface of the preexisting epimatium. The sequence of parts is acropetal, rather than basipetal as previously reported. The consistency of the developmental process supports the hypothesis that the function of the epimatium is to produce an inverted ovule, essential for pollen scavenging via an extended pollination drop. Cone structure and position in relation to shoot construction, phenology of cone development, and correlation between the timing of development in cones and parent shoots are all shown to be interrelated.
Article
Seed production in conifers involves an extended sequence of developmental events that may take as long as 3 years to complete. There is a conflict between two major processes: initial pollination of ovules and subsequent maturation of seeds after fertilization. The conflict arises because ovules must be exposed at first to receive pollen (the gymno-ovulate condition), and subsequently seeds must be protected during maturation (the angiospermous condition). The "Florin model", which shows that the coniferous cone was ancestrally a compound structure, provides a constructional "Bauplan" whose modifications can be understood by developmental study. In the majority of conifers there is no consistent ovule-bearing structure, even though this is required by the model; much of cone ontogeny is determined by intercalary meristematic activity that results in cone closure after pollination. Two main constructional types can be recognized. In Cephalotaxaceae, Cupressaceae, Sciadopityaceae, Taxaceae, and Taxodiaceae (all without saccate pollen), pollen structure and function is uniform and not associated with special modification of the ovulate cone at the time of pollen capture. In the Pinaceae and Podocarpaceae (mostly with saccate pollen), the ovulate cone is usually highly specialized with regard to pollen capture. In the former group, developmental emphasis is on postpollination events that lead to seed protection or are associated with seed dispersal. In the latter group, there is a duality in ovulate cone morphology, initially associated with pollination, and subsequently with seed protection and dispersal. The general conclusion is that the coniferous cone cannot be treated as a static entity for comparative purposes. The functional attributes of cone structures need to be considered in a very broad context when the evolution of the coniferous cone is discussed.Key words: conifers, development, pollen capture, seed cone.
Article
The morphology of the female conifer cones has long been a matter of dispute. In 1900 an account of the theories put forward so far was given by Worsdell. After a brief characterization of the situation at that time, the present article deals with the later history of the subject. At the turn of the century there were rivalling concepts of the nature of the so‐called ovuliferous scale in the conifers: ( a ) the Excrescence or Ligular theory of Sachs‐Eichler, ( b ) the general Brachyblast theory of Braun, Caspary, čelakovský and others, ( c ) van Tieghem's modification of the Brachyblast theory, and ( d ) the Foliolar theory of Delpino‐Penzig. In the subsequent three decades the discussion proceeded on the same or similar lines. The Excrescence theory retained a strong position until the end of the nineteen‐twenties, but, as before, some morphologists professed the general Brachyblast theory. Herzfeld and Wettstein considered that the axillary conifer strobilus had one or more reduced carpels (megasporophylls) which were used up in the formation of terminal ovules, as well as an ‘ovuliferous scale’ consisting of secondary outgrowths from the strobilar axis. In Goebeľs opinion these outgrowths were instead produced by the megasporophylls. Doubts were expressed of the unity of the true conifer group, but Eames showed that the apparently widely different female cones of the Pinaceae and Araucariaceae are homologous, and that the Araucariaceae, Taxodiaceae and Podocarpaceae exhibit complete transitions by fusion and reduction from types with distinctly compound strobilar units–each with an ‘ovuliferous scale’ in the axil of a bract–to others of the most simple form. In contradistinction to the true conifers, the genus Taxus has no compound strobilus, and its ovule is a direct continuation of the axis of the fertile short shoot (Dupler). In the first half of the period after 1930 opinions differed as much as ever, although the general Brachyblast theory now prevailed over the Excrescence theory and other concepts. Chadefaud believed the ‘ovuliferous scale’ and the bract to represent between them a carpel derived from a prototype analogous to the pinnate megasporophyll of Cycas . Hirmer interpreted the ‘ovuliferous scale’ and the bract as formed by a serial splitting of one single member. Lanfer supported Goebeľs views of the terminal position of the conifer ovules on reduced megasporophylls, and of the nature of the ‘ovuliferous scale’. In Hagerup's opinion the female cones of most true conifers are compound and have a short secondary axis developed axillary to each bract. This axis was supposed to carry two transversal prophylls, fertile (megasporangial) or sterile, and a varying number of sterile leaves; and the megasporophyll, with a megasporangium on its upper side, to constitute the integument of the ovule, and be homologous to a lycopod sporophyll. Florin (1938‐45) found that the Palaeozoic cordaites and conifers furnished the principal clue to the interpretation of the true conifer cones of Mesozoic and more recent age. Primarily, the fertile seed‐scale complex in the axil of each bract was a radially symmetrical short shoot (strobilus) with several sterile scales and one to a few uniovulate megasporophylls; the ovules were terminal in position. The later types of cones have arisen by the reduction and transformation of this primitive organization, which in the majority of cases has differentiated the strobilus into a proximal fertile part facing the cone axis and a distal sterile part (‘ovuliferous scale’), while its anterior sector facing the bract became totally suppressed. Exceptionally, no ‘ovuliferous scale’ at all was developed, and the strobilus became wholly fertile. The ovular integument is a continuation of the megasporophyll, and appears to arise out of two transversal primordia at its apex. The taxads differ from the true conifers by their simple strobili being placed axillary on reduced vegetative shoots. Their ovules are seated terminally on the strobilar axis itself; megasporophylls are accordingly absent. The living and extinct genera which have previously as a rule been considered coniferous represent therefore two separate subdivisions of the gymnosperms–the true conifers, and the taxads. Earlier concepts of the morphology of the female cones of the conifers, and of the nature of the integument of their ovules, are in part or wholly untenable.
Article
Mature healthy grape berries and berries wound-inoculated with the fungusBotrytis cinerea were examined by1H NMR microimaging using 2D and 3D spin echo and gradient echo procedures. These NMR images were compared with representations obtained by conventional histology, where possible using the same specimens. 3D imaging datasets from excised seeds were reconstructed by surface rendering and maximum intensity projection to allow interpretation of their internal structure. T2-weighted spin echo images revealed the major features of the pericarp, septum and loculi of whole berries. T1-weighted images were less discriminatory of parenchyma tissues in the fruit but revealed the endosperm in seeds as a chemically shifted feature. A non-invasive study by T1-weighted spin echo NMR imaging of infection byB. cinerea over a 6-day period showed that the disease spread throughout the exocarp but failed to spread in the mesocarp, a result confirmed by histological examination of the same specimen. Surface rendering of 3D datasets of excised seeds revealed the two ruminations of the endosperm and the distal location of the chalaza. The position of the embryonic axis was revealed in T2-weighted maximum intensity projections. This noninvasive study revealed the need to apply a range of imaging techniques and parameters to visualise the structural features of the different parts of the grape berry.
Article
 The phylogenetic position of Parasitaxus (Podocarpaceae) has been inferred from a cladistic analysis of molecular characters from chloroplast and nuclear genomes including all genera of Podocarpaceae. In all 24 most parsimonious trees, based on combined datasets, Phyllocladus resided outside Podocarpaceae s. str. while Lepidothamnus was basal to the latter. Most other genera were arranged in two major clades. The evidence confirms previous studies, which have suggested a relationship between Lagarostrobos, Manoao and Parasitaxus. Parasitaxus is not directly related to its host Falcatifolium taxoides. Instead it appears to be most closely related to Manoao and Lagarostrobos. No other members of this group now occur on New Caledonia. However, if the evolution of Parasitaxus were autochthonous, a free-living member of this group must once have occurred there. An accelerated evolutionary rate of the chloroplast sequence analysed was suggested, indicating that the plant behaves like a holoparasite.
Article
Maximum parsimony analyses of the genera of Podocarpaceae were conducted using sequence data from 18S ribosomal DNA. Trees from sequence, morphological, and combined data differ in taxon arrangement, but are similar in that Podocarpus sensu lato and Dacrydium s.l. are unnatural, while Podocarpaceae (including Phyllocladus) are monophyletic. The clade Microcachrys + Microstrobos is recognized in all analyses, but its placement differs, i.e., nested among other scale-leaved taxa in the morphological analysis, but associated with Nageia and other tropical genera in the sequence analyses. Trees from combined data reflect this ambiguity. Podocarpus sensu stricto is paraphyletic according to most trees. Inferences of plesiomorphic character states within the family are largely consistent between analyses and support the view that prototypical podocarps had bifacial leaves, cones with several fertile cone scales, and large epimatia (cone scales) that covered the inverted ovules.
Article
An outline is given of nuclear magnetic resonance (NMR) microscopy and its application to plant science. An NMR microscope non-destructively detects free water in tissues and creates anatomical images of the tissues. Since the quantity and mobility of cell-associated water is closely related to the condition of the cells,1H-NMR images represent physiological maps of the tissue. In addition, the technique locates soluble organic compounds accumulated in the tissues, such as sugars in vacuoles or fatty acids stored as oil droplets in vesicles.23Na-NMR imaging is suitable for studying the physiology of salt-tolerant plants. Diffusion measurements provide information about the transport of substances and ions accompanied by water movement. The recently developed techniques of three-dimensional imaging, flow-encoded imaging and spectroscopic imaging open up new opportunities for plant biologists. The NMR microscope is thus a unique and promising tool for the study of living plant systems in relation to morphology, the true features of which are often lost during preparation for more conventional tissue analysis. Copyright 2000 Annals of Botany Company
Article
Arabidopsis inflorescence stems develop a vascular pattern similar to that found in most dicots. The arrangement of vascular tissues within the bundle is collateral, and vascular bundles in the stele are arranged in a ring. Although auxin has been shown to be an inducer of vascular differentiation, little is known about the molecular mechanisms controlling vascular pattern formation. By screening ethyl methanesufonate-mutagenized populations of Arabidopsis, we have isolated an avb1 (amphivasal vascular bundle) mutant with a novel vascular pattern. Unlike the collateral vascular bundles seen in the wild-type stems, the vascular bundles in the avb1 stems were similar to amphivasal bundles, i.e. the xylem completely surrounded the phloem. Furthermore, branching vascular bundles in the avb1 stems abnormally penetrated into the pith, which resulted in a disruption in the ring-like arrangement of vascular bundles in the stele. The avb1 mutation did not affect leaf venation pattern and root vascular organization. Auxin polar transport assay indicated that the avb1 mutation did not disrupt the auxin polar transport activity in inflorescence stems. The avb1 mutation also exhibited pleiotropic phenotypes, including curled stems and extra cauline branches. Genetic analysis indicated that the avb1 mutation was monogenic and partially dominant. The avb1 locus was mapped to a region between markers mi69 and ASB2, which is covered by a yeast artificial chromosome clone, CIC9E2, on chromosome 5. Isolation of the avb1 mutant provides a novel means to study the evolutionary mechanisms controlling the arrangement of vascular tissues within the bundle, as well as the mechanisms controlling the arrangement of vascular bundles in the stele.
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