Single Ovule Research Articles

Morphological Study on the Differentiation of Flower Buds and the Embryological Stages of Male and Female Floral Organs in Lespedeza davurica (Laxm.) Schindl. cv. JinNong (Fabaceae).

Lespedeza davurica (Laxm.) is a leguminous plant with significant ecological benefits, but its embryonic development mechanism remains unclear. We investigated the flower bud differentiation, megaspore and microspore formation, gametophyte development, and embryo and endosperm development in L. davurica. Our aim was to elucidate the relationship between the external morphology and internal development processes of male and female floral organs during growth, as well as the reproductive factors influencing fruiting. The results indicated that although the pistil develops later than the stamen during flower bud differentiation, both organs mature synchronously before flowering. L. davurica pollen exhibits three germination grooves, a reticulate outer wall, and papillary structures on the anther surface. In vivo pollination experiments revealed abnormal spiral growth of L. davurica pollen tubes within the style and the occurrence of callus plugs, which may reduce the seed setting rate. The anther wall development follows the dicotyledonous type, with tetrads formed through microspore meiosis exhibiting both left-right symmetry and tetrahedral arrangements. L. davurica has a single ovule, and the embryo sac develops in the monosporic polygonum type. After dormancy, the zygote undergoes multiple divisions, progressing through spherical, heart-shaped, and torpedo-shaped embryo stages, culminating in a mature embryo. A mature seed comprises cotyledons, hypocotyl, embryo, radicle, and seed coat. Phylogenetic tree analysis reveals a close genetic relationship between L. davurica and other leguminous plants from the genera Lespedeza and Medicago. This study provides valuable insights into the regulation of flowering and hybrid breeding in leguminous plants and offers a new perspective on the development of floral organs and seed setting rates.

Reproductive biology of Centaurea kilaea (Asteraceae, Cardueae) – an endemic species from Türkiye

In this study, the embryology of Centaurea kilaea Boiss., a species endemic to Türkiye, was examined using light microscopy. The anthers of C. kilaea are tetrasporangiate; the anther wall development is dicotyledonous; and the tapetum is amoeboid. The meiotic division of the microspore mother cells is regular, and when the pollen grains are thrown from the anthers, they are three-celled. The ovary of C. kilaea is inferior, bicarpellary, syncarpous, and unilocular, which is characteristic of the Asteraceae family. It carries only a single ovule with basal placentation. The ovule is anatropous, unitegmic, and tenuinucellate. The megaspore mother cell undergoes meiotic division, giving rise to a linear tetrad of megaspores. The chalazal megaspore remains functional, and the other three megaspores degenerate rapidly. The functional megaspore undergoes three mitotic divisions in succession. As a result, a Polygonum-type embryo sac, with eight nuclei and seven cells, is formed. The antipodal cells persist until the first divisions of the zygote. In the mature embryo sac stage, the integument consists of the endothelium, peri-endothelial region, parenchymatous cells, and outer epidermis, from the inside out. Endosperm development is initially free nuclear, becoming cellular in the globular embryo stage. Embryo development is of the asterad type. The mature seed does not contain endosperm, but the endothelium persists.

Morpho Evo-Devo of the Gynoecium: Heterotopy, Redefinition of the Carpel, and a Topographic Approach.

Since the 19th century, we have had countless debates, sometimes acrimonious, about the nature of the gynoecium. A pivotal question has been whether all angiosperms possess carpels or if some or all angiosperms are acarpellate. We can resolve these debates if we do not define the carpel as a closed megasporophyll but simply as an appendage that encloses the placenta or a single ovule. This redefinition may, however, lead to confusion because often it may not be clear whether the traditional (classical) definition of the carpel or the redefinition is implied. Therefore, a topographic approach is proposed that is compatible with the redefinition. According to this approach, gynoecia comprise one or more gynoecial appendages and placentas or single ovules that may be formed in different positions. Heterotopy refers to these different positions. In the context of evo-devo, which explores evolutionary changes in development, morpho evo-devo delves into spatial shifts of the placentas and ovules leading to heterotopy. Furthermore, it considers shifts in timing (heterochrony) and other processes leading to heteromorphy. Recognizing spatial shifting of the placentas or a single ovule and other evolutionary processes opens up new vistas in the search for the ancestor(s) of angiosperms and their gynoecia.

Abnormalities in Stamen and Ovary Development Responsible for Low Seed Set of Dendrocalamus hamiltonii Nees et Arn. ex Munro

Bamboo propagation and seed collection are severely limited by a protracted and unpredictable flowering cycle. Dendrocalamus hamiltonii Nees et Arn. ex Munro was renowned for its delectable, bitter-free bamboo shoots, making it an exceptional choice for culinary purposes, which has significant economic value in China. To date, no fruit has been collected, and there are currently no comprehensive studies available on the floral morphology and embryology of D. hamiltonii. The morphological and anatomical characteristics of floral organs were described, and the developmental process of male and female gametophytes was elucidated, through anatomical observation. It was found that the floret of D. hamiltonii was composed of one lemma, palea, pistil, and six stamens, but lacked lodicules. The single ovule, possessing a parietal placenta, was anatropous and featured a double integument. The floral organs showed normal in external morphology, whereas male and female gametophyte development was abnormal, such as pollen grain shrinkage, hollow anther chambers, and underdeveloped ovules, which might be the important factors of its low seed setting rate. This study provided important information on the developmental stages of D. hamiltonii flowers and offered a theoretical basis for understanding the low seed setting rate of bamboo.

Increased Zygote-Derived Plantlet Formation through In Vitro Rescue of Immature Embryos of Highly Apomictic Opuntia ficus-indica (Cactaceae).

O. ficus-indica (prickly pear cactus) is an important forage and food source in arid and semiarid ecosystems and is the most important cactus species in cultivation globally. The high degree of apomixis in the species is a hindrance in plant breeding programs where genetic segregation is sought for the selection of superior genotypes. To understand if in ovulo embryo rescue could increase the proportion of zygotic seedlings, we compared the mature seed-derived seedlings with those regenerated from in vitro embryo rescue at 20, 25, 30, 35, and 40 post-anthesis days (PADs) in four Italian cultivars. The seedlings were classified as apomictic or zygotic based on molecular marker analysis using inter-sequence single repeat (ISSR) primers. Multiple embryos were recovered from all the cultured immature ovules, and plantlets were regenerated and acclimatized to the field post hardening, with success rates ranging from 62% ('Senza spine') to 83% ('Gialla'). The level of polyembryony differed among cultivars and recovery dates, with the highest being 'Rossa', producing 4.8 embryos/ovule at 35 PADs, and 'Gialla', the lowest, with 2.7 at 40 PADs. The maximum number of embryos observed within a single ovule was 14 in 'Trunzara bianca'. ISSR analysis revealed that ovule culture at 35 PADs produced the highest percentage of zygotic seedlings in all the cultivars, from 51% ('Rossa') to 98% ('Gialla'), with a high genotype effect as well. Mature seeds produced much fewer seedlings per seed, ranging from 1.2 in 'Trunzara bianca' to 2.0 in 'Rossa' and a lower percentage of zygotic seedlings (from 14% in 'Rossa' to 63% in 'Gialla'). Our research opens a pathway to increase the availability of zygotic seedlings in O. ficus-indica breeding programs through in ovulo embryo culture.

REPORT OF A BICARPELLARY FLOWER FROM THE DECCAN INTERTRAPPEAN SERIES OF MOHGAONKALAN, INDIA.

The present flower from its oblique transverse section appears to be the smaller in size among the flowers reported from the Deccan Intertrappean series. It is 1.00 X 1.22 mm in diameter. Swollen at middle and tapering at its ends indicate its companulate shape. The flower is actinomorphic, hermaphrodite, pentamerous and hypogynous. The perianth lobes are ten in numbers arranged in two whorls of 5+5 each. The outer whorl contains five tepals may be termed as calyx while the inner five may be as corolla. Stamens are five in number, polyandrous giving pentamerous appearance to the flower. Pollen grains are tricolpate and psilate without any external outgrowth. The anther is basifixed. Gynoecium is bicarpellary, syncarpous with superior, bilocular ovary. Each locule contains single ovule in it with axile placentation. Ovary wall is multilayered and smooth. The present flower is totally different from the reported fossil flowers and living genera of modern families. Hence it is kept under separate form genus Mohgaoanthus deccanii gen. et sp. nov.

The role of pollination in controlling Ginkgo biloba ovule development.

Summary Generally, in gymnosperms, pollination and fertilization events are temporally separated and the developmental processes leading the switch from ovule integument into seed coat are still unknown. The single ovule integument of Ginkgo biloba acquires the typical characteristics of the seed coat long before the fertilization event. In this study, we investigated whether pollination triggers the transformation of the ovule integument into the seed coat.Transcriptomics and metabolomics analyses performed on ovules just prior and after pollination lead to the identification of changes occurring in Ginkgo ovules during this specific time.A morphological atlas describing the developmental stages of ovule development is presented. The metabolic pathways involved in the lignin biosynthesis and in the production of fatty acids are activated upon pollination, suggesting that the ovule integument starts its differentiation into a seed coat before the fertilization.Omics analyses allowed an accurate description of the main changes that occur in Ginkgo ovules during the pollination time frame, suggesting the crucial role of the pollen arrival on the progression of ovule development.

Flower structure and development in Vietnamese Sciaphila (Triuridaceae: Pandanales): refined knowledge of the morphological misfit family and implications for taxonomy.

The monocot family Triuridaceae is a morphological misfit with respect to several traits of floral morphology, including the uniformly apocarpous polymerous gynoecium and the famous inside-out flowers of Lacandonia. Although Triuridaceae are crucially important for understanding the floral evolution of Pandanales and angiosperms in general, significant knowledge gaps exist which hamper adequate morphological analysis of flowers in this family. The scarcity of morphological data is also reflected in numerous taxonomic inconsistencies. Here we provide a comprehensive study of reproductive organs of four species of Sciaphila occurring in Vietnam (S. arfakiana, S. densiflora, S. nana and S. stellata) including the first investigation of early floral development and gynoecium phyllotaxis. Our observations are mainly based on SEM images. We confirm the perianth (studied in male flowers) to be two-whorled and report a rare sequence of initiation of perianth parts: the outer tepals show a late congenital fusion, as their free lobes appear before the common perianth tube, whereas the inner tepals show an early congenital fusion, with their free lobes initiating on the tube rim. We interpret the stamen appendages as basal adaxial outgrowths of the stamen filaments. We discuss the number of thecae and locules in anthers of Sciaphila, and conclude that 3- and 4-, but not 2-locular anthers are characteristic of this genus. We describe the carpels as consisting of both ascidiate and plicate zones, the former being extremely short and completely obscured by anthesis. The single ovule is attached in the cross-zone. The style is non-plicate. We analyze gynoecium phyllotaxis by estimating its contact parastichies, and by investigating the number and arrangement of the outermost carpels. The carpel arrangement in a given gynoecium is a result of the balance between whorled and irregular (but not spiral) phyllotaxis. We recognize the following figures of gynoecium merism: 6, 9, 10, 10.5, 11 and 12, with the prevalence of those divisible by three. We discuss our results in the light of general diversity of floral structure of monocots. Our data allow to clarify several issues in taxonomy of Asian Sciaphila and indicate directions of further studies. We report a significant range extension for S. densiflora, which is newly recorded for the flora of Vietnam. We describe for the first time staminodes in female flowers of this species. We reveal two distinct morphs of S. nana in Vietnam. We highlight the need of a thorough revision of S. secundiflora species complex in order to verify the species boundaries and, in particular, to test the identity of the Vietnamese S. stellata.

Floral morphology and pollination system of Syzygium guineense (Willd.) DC. subsp. macrocarpum (Engl.) F. White (Myrtaceae), a subspecies with high nectar production

The floral morphology and pollination of S. guineense subsp. macrocarpum were investigated on ten trees selected for a study of floral phenophases in the natural forest of Bassila, located in the Sudano-Guinean zone (Benin). For the floral analysis, the two stages considered were flower buds for preflowering data and open flowers for flower data. To determine the pollination mode and identify main pollinators, two stages were considered, namely flower bud and initiated fruits. The fruit set, autogamy and allogamy rate were assessed. Results show that several flower morphological traits predispose this species to selfing and cross pollination, including hermaphroditism and a long anther–stigma distance. The symmetry is actinomorphic with a floral receptacle adnate to the ovary. The latter is inferior, bicarpellary and bilocular syncarpous and contains 18–22 ovules on an axile placenta. Only a single ovule is fertilized and becomes a seed. Visitors frequently registered on the flowers of S. guineense subsp. macrocarpum are exclusively insects belonging to six orders, including Diptera (26%), Hymenoptera (24%), Lepidoptera (19%). The mean fruit set was 0.47 ± 0.10 for the open-pollination experiments and 0.27 ± 0.12 for autogamous self-pollination. The autogamy rate was 57.45% and the allogamy rate 42.55%. This study confirms that S. guineense subsp. macrocarpum is predominantly autogamous. Self-compatibility is not for exceptional species, but a dominant characteristic of the genus Syzygium. The viability of the pollen grains and receptivity of the stigma at each flowering stage should be further studied.

Tupistra siphonantha (Asparagaceae), a new species from Lao P.D.R. with a simple pistil

Tupistra siphonantha N. Tanaka, Vislobokov & D. P. Hannon, a new species from central Laos is described and illustrated. It is distinguishable from all other members of Tupistra mainly by the synchronously blooming flowers, clavate-tubular, cream-white or fulvous perianth with strongly incurved segments, latrorse anthers with thecae separated by a round (papillary) projection from the perianth, and very small, simple pistil bearing a single ovule in the locule. It is also unique in having ellipsoid, smooth, orange fruits that are similar to those of Rohdea. The taxonomic position and features of the flowers and fruits of this species are briefly discussed. A key to the species of Tupistra reported from Laos is also provided.

Effect of Flower Pollination on Fruit Set and Cropping in Apple

Apple (<i>Malus x domestica</i> Borkh.), being self-incompatible, requires cross-pollination to set fruit regularly. Apple flowers contain ten ovules and the higher the number of fertilized ovules, the larger the fruit size. In commercial orchards, cross pollination is usually guaranteed by intercropping different cultivars and by introducing beehives in the orchard at flowering time. Despite evidence that pollen donors should be close for successful pollen transportation, apple growers often plant large monovarietal blocks with negative consequences on crop load and fruit size. The contribution of wind and bees to apple pollination was studied and compared with hand-pollination in two apple cultivars, ‘Royal Gala’ and ‘Golden Delicious’. Self-pollination was also included as control. Each treatments was replicated in 120 cymes randomly assigned to plants in the central part of large monovarietal blocks (1.61 and 2.72 ha respectively). Fruit set and fruit weight increased moving from wind-pollination to wind + bee-pollination to hand-pollination as a consequence of the increase in the number of seeds per fruit. Fertilization of a single ovule was enough to set fruit after flowering, but the more seed, the larger the fruit. The increase in fruit weight per additional seed was 2.0 g for ‘Royal Gala’ and 4.6 g for ‘Golden Delicious’. This relationship between seed count and fruit weight resulted in fruit set by wind-pollination being mainly in the lower size classes, while wind + bee-pollination and, largely, hand-pollination shifted the fruit size distribution towards larger size classes. This resulted, in turn, in a dramatic increase in grower income. No significant difference between treatments in fruit quality, as assessed by fruit firmness, soluble solids content, titratable acidity, dry matter and starch content, was observed after fruit storage. It is concluded that limiting pollination in the hope of reducing the labor of thinning is not a good strategy, because flowers set fruit with a minimal cross-pollination, even if only a single seed is produced; conversely, the low seed content of fruit due to insufficient pollination is responsible for great losses for grower in both total crop yield and income.

Synchrotron computer tomographic (CT) scans complement traditional techniques in understanding the internal anatomy of permineralised Fontainocarpa (Crotonoideae, Euphorbiaceae) fruits from the Oligocene of eastern Australia

The internal morphology and anatomy of silicified fruits of Fontainocarpa were studied using traditional thin sectioning techniques, SEM and synchrotron computed tomographic (CT) imaging and animations, to enable comparative analyses with extant, indehiscent-fruited genera in the Euphorbiaceae including Fontainea, Aleurites and Hylandia from Australia, and other non-Australian crotonoid genera. Thin sections and sectioning show that the fruits of Fontainocarpa are indehiscent, multicarpellate and usually 3- to 5-loculate, with axial placentation, a single ovule per carpel and the ovules are anatropous and have antitropous curvature. A ventral vascular trace that supplies each ovule is embedded in the bitegmic seed coat. The internal anatomy is therefore consistent with the Euphorbiaceae. Additional characters, including indehiscent fruits, distinctive vascular channels (foramina) that penetrate through the fruit wall into the locule, and thin membranous seed coats are restricted to very few genera in the Euphorbiaceae, but occur together in extant Fontainea. The seed coat in extant Fontainea and fossil Fontainocarpa seeds is membranous, and appears to lack the palisadal exotegmen of most genera in the Euphorbiaceae. Fontainocarpa fruits were compared with those of extant Fontainea and the fossil has a combination of features unlike those of extant taxa. It shares with Fontainea picrosperma in having endocarps with convex intersutural surfaces lacking ornamentation and a similar number of locules and with Fontaineavenosa in having conspicuous foramina. This study therefore supports a close relationship between Fontainea and Fontainocarpa and is further evidence of the Crotonoideae in the fossil record in Australia, and is one of the few records of this subfamily worldwide. This study is one of the few, to date, using synchrotron CT imaging to reveal the internal morphology of silicified fruits and to utilize animations to examine the structure of these fruits.

Patterns of angiospermy development before carpel sealing across living angiosperms: diversity, and morphological and systematic aspects

Almost all angiosperms are angiospermous, i.e. the ovules are enclosed in carpels at anthesis and during seed development, but angiospermy develops in different ways across angiosperms. The most common means of carpel closure is by a longitudinal ventral slit in carpels that are partly or completely free. In such carpels, the closure process commonly begins at midlength of the prospective longitudinal slit and then proceeds downward and upward. Closure by a transverse slit is rarer, but it is prominent in groups of the ANITA grade and in a few early branching monocots (some Alismatales) and some early branching eudicots (a few Ranunculaceae and Nelumbonaceae), in these eudicots combined with a more or less developed longitudinal slit. In all these cases the carpels have a single ovule in ventral median position. In ANITA lines with pluriovulate carpels, there is only a short longitudinal slit in the uniformly ascidiate carpels. In carpels with a unifacial style the closure area is narrow; this pattern is rare and scattered mainly in some wind-pollinated monocots and eudicots. In most angiosperms the carpels become closed before the ovules are visible from the outside of the still incompletely closed carpels (early carpel closure). This is notably the case in the ANITA grade and magnoliids. Delayed carpel closure, with the ovules visible before the carpels are closed, is much rarer and is concentrated in a few monocots (mainly some Alismatales and some Poales) and a few eudicots (mainly a few Ranunculales and many Caryophyllales, and scattered in some other eudicots). A kind of delayed carpel closure (with the placenta visible before closure but mostly not the ovules) also occurs in syncarpous gynoecia with a free central placenta. Most gynoecia with a free central placenta occur in the superasterids. In such gynoecia the individual carpel tips are not differentiated but the opening in young gynoecia has the shape of a circular diaphragm. In this case, when ovary septa and free carpel tips are missing, the number of carpels is sometimes unclear (Primulaceae, Lentibulariaceae, some Santalaceae). Extremely ascidiate carpels are concentrated in the ANITA grade, a few magnoliids and some early branching monocots. Aspects of potential advantages of plicate vs. ascidiate carpels with regard to flexibility of pollen tube transmitting tract differentiation are discussed. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 556–591.

Ontogenesis of the pseudomonomerous fruits of Acrocomia aculeata (Arecaceae): a new approach to the development of pyrenarium fruits

The formation of an oleaginous palm fruit was described by anatomical and physiological evaluations that allowed us to correlate and associate pericarp and seed ontogenesis and define the developmental phases. The pseudomonomerous pyrenarium fruits of Arecaceae demonstrate complex and slow development pathways, and accumulate large quantities of energy reserves, making them of economic interest. Very little is known about the association between pericarp and seed development in this family. We characterize here the ontogenesis of Acrocomia aculeata fruits, a neotropical oleaginous palm, define their developmental phases, investigate the relationship between embryogenesis and fruit development, and describe the formation of structures related to dormancy and reserve accumulation. The development of the pistillate flowers and fruit structures were accompanied over time and evaluated biometrically, anatomically, and through histochemical tests. Bromatological evaluations were performed on the mesocarp and seeds during their reserve accumulation phases. A. aculeata flowers are tricarpellate and syncarpous, although normally only a single ovule develops; the other ovules degenerate and become incorporated into the pyrene. The seed is pachychalazal and embryogenesis is precocious in relation to fruit development. The exocarp is the first pericarp structure to attain maturity, while the pyrene undergoes significant lignification, except for the region near the abscission zone and acquires a petrous consistency. The development of the endocarp is restricted to the germination pore plate and seed operculum, and is associated with dormancy restrictions. The accumulation of lipids in the mesocarp occurs near the time of abscission. A. aculeata fruits require approximately one year for full development, which occurs in three phases: the histo-differentiation of the pericarp; seed maturation; and mesocarp maturation.

X-ray Synchrotron Microtomography of a silicified Jurassic Cheirolepidiaceae (Conifer) cone: histology and morphology of Pararaucaria collinsonae sp. nov.

We document a new species of ovulate cone (Pararaucaria collinsonae) on the basis of silicified fossils from the Late Jurassic Purbeck Limestone Group of southern England (Tithonian Stage: ca. 145 million years). Our description principally relies on the anatomy of the ovuliferous scales, revealed through X-ray synchrotron microtomography (SRXMT) performed at the Diamond Light Source (UK). This study represents the first application of SRXMT to macro-scale silicified plant fossils, and demonstrates the significant advantages of this approach, which can resolve cellular structure over lab-based X-ray computed microtomography (XMT). The method enabled us to characterize tissues and precisely demarcate their boundaries, elucidating organ shape, and thus allowing an accurate assessment of affinities. The cones are broadly spherical (ca. 1.3 cm diameter), and are structured around a central axis with helically arranged bract/scale complexes, each of which bares a single ovule. A three-lobed ovuliferous scale and ovules enclosed within pocket-forming tissue, demonstrate an affinity with Cheirolepidiaceae. Details of vascular sclerenchyma bundles, integument structure, and the number and attachment of the ovules indicate greatest similarity to P. patagonica and P. carrii. This fossil develops our understanding of the dominant tree element of the Purbeck Fossil Forest, providing the first evidence for ovulate cheirolepidiaceous cones in Europe. Alongside recent discoveries in North America, this significantly extends the known palaeogeographic range of Pararaucaria, supporting a mid-palaeolatitudinal distribution in both Gondwana and Laurasia during the Late Jurassic. Palaeoclimatic interpretations derived from contemporaneous floras, climate sensitive sediments, and general circulation climate models indicate that Pararaucaria was a constituent of low diversity floras in semi-arid Mediterranean-type environments.

Lauraceous Fossil Flowers from the Kamikitaba Assemblage (Coniacian, Late Cretaceous) of Northeastern Japan (Lauraceae)

A new genus and species of Lauraceae, Microlaurus perigynus gen. et sp. nov. is described based on fossil charcoalified flower buds recovered from the Kamikitaba assemblage (early Coniacian, Late Cretaceous; ca. 89 million years before present (myr BP)) in the Ashizawa Formation (Asamigawa Member) of the Futaba Group in northeastern Japan. Analysis of the internal structure of the fossil buds using synchrotron-radiation X-ray microtomography (SRXTM) at the 2-BM-B beamline of the Advanced Photon Source (APS), Argonne National Laboratory, shows that the flowers are small, pedicellate, bisexual, trimerous, and actinomorphic, with small outer tepals, larger inner tepals, three whorls of stamens, an innermost androecial whorl composed of staminodia, and a unicarpellate gynoecium containing a single ovule. Microlaurus perigynus is assigned to the Lauraceae based on the regular trimerous floral organization and other details of floral structure, but it is distinguished from most previously described lauraceous fossil flowers by the poorly differentiated filament and anther in the stamens of the third whorl and the marked size difference between the small outer tepals and the large inner tepals. Also unusual are the paired glandular appendages that appear to be associated with the first (outermost) whorl of stamens, rather than the stamens of the third whorl, although the precise position is not fully clear. The same feature occurs in Hernandiaceae, the sister group of Lauraceae, as well as in Powhatania connata, an earlier but fragmentary lauralean fossil flower from the Early to Middle Albian of Virginia. Microlaurus perigynus adds to the floral diversity of Lauraceae known from the Late Cretaceous, and its presence in the Kamikitaba assemblage from Japan underlines the broad geographic distribution and floristic significance of lauraceous plants during the Late Cretaceous.

(2189) Proposal to conserve the name Pityostrobus against Zamiostrobus (fossil Gymnospermae, Pinopsida)

TAXONVolume 62, Issue 4 p. 842-842 Proposals to Conserve or Reject NamesFree Access (2189) Proposal to conserve the name Pityostrobus against Zamiostrobus (fossil Gymnospermae, Pinopsida) Alexander B. Doweld, Corresponding Author Alexander B. Doweld nicar-sekretariat@yandex.ru National Institute of Carpology (Gaertnerian Institution), 21 Konenkowa Street, Moscow, 127560 Russian FederationSearch for more papers by this author Alexander B. Doweld, Corresponding Author Alexander B. Doweld nicar-sekretariat@yandex.ru National Institute of Carpology (Gaertnerian Institution), 21 Konenkowa Street, Moscow, 127560 Russian FederationSearch for more papers by this author First published: 27 December 2018 https://doi.org/10.12705/624.23AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume62, Issue4August 2013Pages 842-842 RelatedInformation

&lt;p class="HeadingRunIn"&gt;&lt;strong&gt;Characterization of &lt;em&gt;Hubera&lt;/em&gt; (Annonaceae), a new genus segregated from &lt;em&gt;Polyalthia&lt;/em&gt; and allied to &lt;em&gt;Miliusa&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;

On the basis of molecular phylogenetics, pollen morphology and macromorphology, a new genus of the tribe Miliuseae, Hubera, segregrated from Polyalthia and allied to Miliusa, is established and described. It is characterized by the combination of reticulate tertiary venation of the leaves, axillary inflorescences, a single ovule per ovary and therefore single-seeded monocarps, seeds with a flat to slightly raised raphe, spiniform(-flattened peg) ruminations of the endosperm, and pollen with a finely and densely granular infratectum. Twenty-seven species are accordingly transferred to this new genus.

Gamete Fusion Is Required to Block Multiple Pollen Tubes from Entering an Arabidopsis Ovule

In double fertilization, a reproductive system unique to flowering plants, two immotile sperm are delivered to an ovule by a pollen tube. One sperm fuses with the egg to generate a zygote, the other with the central cell to produce endosperm. A mechanism preventing multiple pollen tubes from entering an ovule would ensure that only two sperm are delivered to female gametes. We use live-cell imaging and a novel mixed-pollination assay that can detect multiple pollen tubes and multiple sets of sperm within a single ovule to show that Arabidopsis efficiently prevents multiple pollen tubes from entering an ovule. However, when gamete-fusion defective hap2(gcs1) or duo1 sperm are delivered to ovules, as many as three additional pollen tubes are attracted. When gamete fusion fails, one of two pollen tube-attracting synergid cells persists, enabling the ovule to attract more pollen tubes for successful fertilization. This mechanism prevents the delivery of more than one pair of sperm to an ovule, provides a means of salvaging fertilization in ovules that have received defective sperm, and ensures maximum reproductive success by distributing pollen tubes to all ovules.

Homologies of the flower and inflorescence in the early‐divergent grass Anomochloa (Poaceae)

The grass subfamily Anomochlooideae is phylogenetically significant as the sister group to all other grasses. Thus, comparison of their structure with that of other grasses could provide clues to the evolutionary origin of these characters. We describe the structure, embryology, and development of the flower and partial inflorescence of the monotypic Brazilian grass Anomochloa marantoidea. We compare these features with those of other early-divergent grasses such as Pharus and Streptochaeta and closely related Poales such as Ecdeiocolea. Anomochloa possesses several features that are characteristic of Poaceae, notably a scutellum, a solid style, reduced stamen number, and an ovary with a single ovule that develops into a single indehiscent fruit. Interpretation of floral patterning in Anomochloa is problematic because the ramification pattern of the florets places the bracts and axes in unusual positions relative to the primary inflorescence axis. Our study indicates that there is a single abaxial carpel in Anomochloa, probably due to a cryptic type of pseudomonomery in Anomochloa that resembles the pseudomonomery of other grasses. On the other hand, the Anomochloa flower differs from the "typical" grass flower in lacking lodicules and possessing four stamens, in contrast with the tristaminate condition that characterizes many other grasses. Using the median part of the innermost bract as a locator, we tentatively homologize the inner bract of the Anomochloa partial inflorescence with the palea of other grasses. In this interpretation, the pattern of monosymmetry due to stamen suppression differs from that of Ecdeiocolea.