Parietal Placentae Research Articles

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.

Primulina clausa, a new species of Gesneriaceae from northern Guangxi, China

A new species of Gesneriaceae, Primulina clausa P.W.Li & M.Kang was described, which occurs in the karst areas of northern Guangxi Zhuang Autonomous Region of China. The new species is morphologically similar to P. obtusidentata (W.T.Wang) Mich.Möller & A.Weber, but can be readily distinguished by its short and prostrate peduncle, slightly unfolded bracts, appressed sepals, glabrous anthers, parietal placenta, and nearly straight capsules.

Structure of long-tubed white corollas: A case study from the trumpet-creeper family (Bignoniaceae)

Hawkmoth-pollinated plant species with white, long-tubed flowers have attracted the attention of scientists for a long time. However, most studies on these flowers have investigated their pollination biology, with only a few focusing on their anatomy. In this study, we conducted a detailed structural analysis of the long-tubed white flowers of Tanaecium jaroba Sw., a species from the “trumpet-creeper” family (Bignoniaceae). An in-depth understanding of the morphology of this flower type is critical for an accurate interpretation of the evolution of this structure. We found that the long floral tube develops as a result of intercalary growth; no increment of number in the flower whorls were observed. We documented osmophores on the apices of the corolla tube for the first time for the family Bignoniaceae. In addition, studies on the vasculature showed a secondary division of the ovary into two locules due to the inward growth and merging of the parietal placentae, forming a placental lamella. Our study highlights the importance of detailed morphological and anatomical studies at lower taxonomic levels, establishing the basis for future studies on the evolution of flower morphology in Bignonieae, and the Bignoniaceae as a whole.

Prockia jaliscana (Salicaceae), a new species from Jalisco, Mexico

Prockia jaliscana is described and illustrated as a new species from the state of Jalisco, Mexico. This species is similar to P. oaxacana; however, it differs from the latter because it is dioecious, presents linear or lanceolate to foliaceous stipules, has male and female flowers different from those of P. oxacana, apetalous staminate flowers and presents an ovary with ovules in both basal and parietal placentae.

Taxonomy of the genus Paris L. (Melanthiaceae) in Vietnam

Paris L. is a small genus distributed widely in Eurasia. In Vietnam Paris occur in evergreen broad-leaved forests in some mountainous areas of the North and the Central highlands. Due to over-exploitation as well as habitat loss, populations of some Paris species are seriously declining. This genus has not been studied extensively in Vietnam. The aim of this study was to define the morphological characteristics of the genus Paris in Vietnam. Morphological description, dichotomous key for identification, ecology and distributions of the genus in Vietnam are reported. The results show that this genus in Vietnam comprises 8 species and 2 varieties, possesing unilocular ovary with parietal placenta.

Ovary and fruit morphology and anatomy of Amphilophium crucigerum

Amphilophium crucigerum (L.) L.G. Lohmann, known as “pente-de-macaco” is a species of Bignoniaceae native to Brazil, and whose seeds are used in folk medicine. This study aimed to describe morphoanatomical features of this species of fruit to aid in its correct identification and pharmacognostic analysis. Samples of ovary, pericarp and seed were fixed with 3% glutaraldehyde, sectioned on a rotary microtome and analyzed by stereomicroscope. The results are shown in three parts: (1) The ovary presents peltate trichomes, long non-glandular trichomes and emergences in the epidermis; it is 2-carpellate and unilocular with two intruding parietal placenta; ovules are numerous on the placenta; it presents a large quantity of crystals. (2) The pericarp is woody, densely echinate and elliptic shape; it presents a 2-valved capsule and is septicidal; it presents emergences, stomata, lenticels, crystals and a large quantity of clustered stones cells. (3) Seeds are alate, exalbuminate and exotestal; there is a large amount of crystals in the exotestal region; it presents an endothelium and remnant endosperm. Histochemical tests showed the presence of lipophilic substances, polysaccharides, phenolic substances, alkaloids and a small quantity of starch. These pharmacobotanical features described for A. crucigerum are essential for the pharmacognostic analysis of the drug plant.

Frankenia fruticosa (Frankeniaceae), a new dwarf shrub from the Knersvlakte, Western Cape

Frankenia fruticosa J.C.Manning & Helme is a new species endemic to the Knersvlakte near Lutzville in Western Cape, South Africa. It is unique among the southern African species in its gnarled, woody habit, the plants forming compact dwarf shrubs up to 35cm high, with small, sausage-shaped leaves, 1.5–2.5mm long. The calyx is densely puberulous and the narrow petals, ±8mm long, have the blade scarcely wider than the claws, with the apex of the ligule merging into the blade, and the ovary has six ovules, a pair near the base of each of three parietal placentas. We provide an updated key to the southern African species of Frankenia.

Thismia singeri (Thismiaceae), an augmented description and first record for Brazil

Thismia singeri, is described for the first time for Brazil, being the first record of this family for Para State and the third record for this rare species in nature. In Para state, northern Brazil, this species was found growing in Itaituba municipality near the River Tapajos, in a well preserved submontane rain forest with a dense canopy. Due to the holotype is incomplete, we provide a more comprehensive description for this species based on complete individuals, thus clarifying some aspects of its morphology such as the parietal placenta, the root system, and tepal morphology. This is the second species of Thismiaceae described for Amazonia. Thismia hyalina, the other Amazonian species, is easily distinguished from T. singeri by its tubers, leaves inserted just below the flower, the latter with two tepal whorls, the upper one clawed, reniform and erect, and the lower one linear triangular.

Floral morphology and structure of Phyllonoma (Phyllonomaceae): systematic and evolutionary implications

Phyllonoma, a small tree genus of four species distributed from Mexico to Peru, has been placed in various families (mainly in Saxifragaceae), but now, based on molecular evidence, is placed in a distinct family Phyllonomaceae in Aquifoliales. To better understand the morphological relationships of the genus and family, I studied its floral morphology, anatomy, and vasculature using P. tenuidens. Most of the external and internal floral characteristics were described more than 120years ago. Although some of them were confirmed, some were substantially revised, mainly those concerning the gynoecial structure. Flowers are small and basically pentamerous, consisting of five sepals, five petals, five stamens, and a gynoecium composed of two carpels usually in transversal position. Comparisons with other Aquifoliales show that Phyllonomaceae share the inferior ovary, epiphyllous inflorescence and epigynous disc nectary with East-Asian Helwingiaceae (Helwingia only), but clearly differ from Helwingiaceae in having glandular trichomes on the sepal margins and a bicarpellate, unilocular gynoecium bearing many ovules on the parietal placentae. Evidence from floral morphology and structure supports the distinctness of Phyllonomaceae and its sister-group relationship with Helwingiaceae. Its floral characteristics suggest that Phyllonomaceae have evolved by adapting to distinct biological habitats in relation to pollination and seed dispersal.

Bertilanthus scanicus, a New Asterid Flower from the Late Cretaceous (Late Santonian–Early Campanian) of Scania, Sweden

A new genus and species of fossil flowers, Bertilanthus scanicus, is described from the Late Cretaceous of southern Sweden. The flowers of B. scanicus are actinomorphic and bisexual with an inferior ovary. Perianth and androecium are pentamerous. The sepals are small and free, and calyx aestivation is apert; petals are larger, and aestivation of corolla is imbricate. The androecium consists of a single whorl of stamens opposite the petals. The anthers are dithecate, tetrasporangiate, sagittate, and dorsifixed. Pollen observed in the flower is minute and oblate to spheroidal with three colpi and a tectate-punctate pollen wall. The gynoecium is formed from two carpels, and there are two free and stout styles. The epidermal cells of the styles are palisade shaped and form a distinct radiating pattern. The ovary is unilocular with numerous anatropous ovules borne on two intruding parietal placentae. There is a distinct five-parted nectary disk inserted between perianth and styles. The fruit was probably dry and capsular with apical dehiscence between the styles. Bertilanthus scanicus shares the presence of the unusual radiating palisade cells of the styles with Silvianthemum suecicum, another taxon described from the Åsen locality based on fossil flowers. Other critical features shared between Bertilanthus and Silvianthemum, including minute, tectate-punctate pollen, papillate-spiny extension of the palisade cells, free and stout styles, unilocular ovary, parietal placentation with placentae extending almost to the center of the ovary, and numerous anatropous ovules with reticulate surface, indicate that the two genera are closely related and also link these fossils to extant Quintinia, currently placed in the Paracryphiaceae (Paracryphiales) in the asterid clade.

Floral development and anatomy of Salvadoraceae

BACKGROUND AND AIMS; This study is an investigation into the floral development and anatomy of two genera of the small family Salvadoraceae, which belongs to the Brassicales in a clade with Batis and Koeberlinia. Salvadoraceae remains little known, despite its wide distribution in arid areas of the globe. Floral morphological data are scarce, and information on floral anatomy is limited to a single study, although morphological and anatomical characters are now used increasingly as a counterpart of molecular data. There remain a number of controversial morphological questions, such as the fusion of the petals, the number of carpels and the nature of the nectaries. Floral anatomy and ontogeny were studied in two species of Salvadora and one species of Dobera. Only for S. persica could a full floral developmental sequence be done. The floral development demonstrates that the ovary of Salvadoraceae is basically bicarpellate and pseudomonomerous with a single locule and parietal placenta. The ovary of Dobera resembles Azima tetracantha in the presence of a false apical septum. Evidence for a staminodial nature of the nectaries is not decisive. In Salvadora petals and stamens are lifted by a short hypanthium. Salvadoraceae share several morphological and developmental synapomorphies with Batis (Bataceae) and possibly Koeberlinia (Koeberliniaceae), supporting their close relationship as indicated by molecular phylogeny.

A New Genus of Holoparasitic Orobanchaceae from Mexico

We describe here a novel achlorophyllous parasite on the roots of Hedyosmum mexicanum C. Cordemoy (Chloranthaceae) as a new genus and species, Eremitilla mexicana Yatskievych & J. L. Contreras. The new taxon is currently thought to be endemic to the state of Guerrero, Mexico. It is best classified in the Orobanchaceae, but differs from other members of the family in having 5-ribbed, muricate ovaries containing five parietal placentae, as well as unusual stamens in which the anther is partially embedded in an expanded filament apex. Within the Orobanchaceae, the new taxon is probably related to a group that contains the other American holoparasitic genera. Morphologically, Eremitilla Yatskievych & J. L. Contreras displays a number of autapomorphies, but few identifiable synapomorphies. This presumed relictual taxon presently is known only from a restricted habitat and a very small geographic range, and thus is of conservation concern.

Begonia coelocentroides Y. M. Shui & Z. D. Wei, a new species of Begoniaceae from Yunnan, China

Begonia coelocentroides Y. M. Shui & Z. D. Wei, a new species of the genus Begonia L. (sect. Platycentrum, Begoniaceae) from Yunnan, China, is described and illustrated. It resembles B. oreodoxa Chun & F. Chun in having parietal placentas at the upper part of the ovary, differing mainly in the female flowers with 5 tepals and the largest wing of the capsule being 20-22 mm long and ligulate.

Microsporogenesis, Megasporogenesis, and the Development of Male and Female Gametophytes in Eustoma grandiflorum

Embryological characters during microsporogenesis, megasporogenesis, and the development of male and female gametophytes in Eustoma grandiflorum were observed by microscopy. The results are as follows. 1. The formation of anther walls was of the dicotyledonous type. The tapetum was of the heteromorphic and glandular type. Tapetal cells on the connective side elongated radially. 2. Cytokinesis in microsporocyte meiosis was of the simultaneous type and microspore tetrads were tetrahedral. 3. Mature pollen grains were 2-celled and had 3 germ furrows. 4. The ovary was bicarpellary syncarpous and unilocular, having parietal placentas. Ovules were numerous and anatropous. 5. The archespore under the nucellar epidermis directly developed a megaspore mother cell, which in turn underwent meiotic division to form 4 megaspores arranged in a line or T-shape. The chalazal megaspore was observed to be functional. 6. The formation of the embryo sac was of the polygonum type. Before fertilization, the 2 polar nuclei fused into a secondary nucleus. The mature embryo sac was made up of 7 cells. 7. It was found at a very low rate that there were 2 megasporocytes or 2 embryo sacs in an ovule.

Comparative floral structure and systematics in Apodanthaceae (Rafflesiales)

Comparative studies on floral morphol- ogy, anatomy, and histology were performed to identify shared features of the genera of Apo- danthaceae (Rafflesiales): Apodanthes, Pilostyles, and Berlinianche. Berlinianche was studied for the first time in detail and its affinity to Apodanth- aceae was confirmed. It has a previously unde- scribed hair cushion on the inner perianth organs and inaperturate pollen. Shared features of mem- bers of Apodanthaceae are: unisexual flowers; three (or four) alternating di-/tetra- or tri-/hexa- merous whorls of scales of which the inner one or two correspond to a perianth; a synandrium with pollen sacs typically arranged in two rings; opening by a dehiscence line between the two rings of pollen sacs; large vesicular hairs above the synandrium; a gynoecium with four united carpels; inferior and unilocular ovaries with four parietal placentae, ovules tenuinucellate, anatro- pous with two well developed integuments, ori- ented in various directions; a nectary disk. Apodanthaceae share some special structural features with Malvales.

INTERRELATION OF CURING AND BOTANY IN VANILLA (VANILLA PLANIFOLIA) BEAN

INTERRELATION OF CURING AND BOTANY IN VANILLA (VANILLA PLANIFOLIA) BEAN

Floral morphology and anatomy of Pittosporum tobira (Pittosporaceae)

Comparative studies are made on floral morphology and anatomy of female and male flowers of Pittosporum tobira. The two types of flower differ little from each other in structure at the early stage of floral development, but appear dimorphic towards anthesis. The male flower becomes cryptically bisexual, although its pistil is slender compared to that of the female flower. The stigmas of the male flower are receptive and can induce pollen germination. The structure of the style in the male flower is identical to that in the female flower. Ovules are produced on the protruded parietal placenta in the male flower, but their development is arrested at the stage of the 4–nucleate embryo sac. The female flower is clearly unisexual, with obviously aborted and sagittate anthers. Its pistil is rather plump and can produce darkish red seeds immersed in sticky pulp. The male and female flowers are similar in vascular anatomy. A conspicuous difference between the two types of flower lies in the stamens. Variation of sexual organs in the genus Pittosporum is reviewed. We assume that the flowers of Pittosporum are derived from the hermaphrodite‐flowered ancestor and the female flower has become unisexual through partial reduction of sexual organs at a faster rate than the male flower.

Patterns and Significance of Floral Development in Whytockia (Gesneriaceae)

Abstract: The floral development of Whytockia W. W. Smith has been studied in order to explore the developmental basis for the arrangement and differentiation patterns of floral organs, and the evolutionary relationship between Whytockia and allies in floral development. The descending imbricate aestivations in both calyx and corolla have remarkably different ontogenetic patterns between calyx and corolla which are derivative with respect to the development of the valvate aestivations in the four‐stamened Rhynchoglossum. Both corolla lobes and stamens are initiated simultaneously from the same ring meristem. However, the five stamens remarkably precede the initiation of the five corolla lobes. Also, the adaxial stamen is suppressed after initiation to become a staminode, concomitant with retardation of its adjacent organs during development. This situation, together with the non‐acropetal order among whorls of floral organs in Whytockia, is possibly related to a late expression and a remarkably different expression pattern of cycloidea‐like genes as compared to Antirrhinum. Furthermore, the axile placentation in the bilocular ovary of Whytockia is formed by an involute closure of carpels rather than derived from a secondary fusion of two intrusive parietal placentae.

Floral development and anatomy ofPentadiplandra(Pentadiplandraceae): a key genus in the identification of floral morphological trends in the core Brassicales

The development and anatomy of leaves and flowers have been investigated in the monotypic species Pentadiplandra brazzeana to discuss its position relative to the core Brassicales and to clarify floral evolutionary trends within the order. Young leaves are flanked by two large stipules that shrivel at anthesis. Young flowers develop as elliptical primordia on a flattened raceme. Sepal initiation is sequential, starting with the lateral sepals and ending with three median sepals. The petals and diplostemonous androecium arise as regular whorls. Five antesepalous carpels develop into a saccate gynoecium with axile placentation. Petals develop a cushion-like basal appendage covering the extrastaminal nectary. Several ontogenetic and anatomical data of the flower support the basal position of Pentadiplandra in the evolution of the core Brassicales and for the derivation of the order from pentamerous diplostemonous ancestors. A derivation of the tetramerous Capparaceae and Brassicaceae as well as hexamerous Tovariaceae is discussed. A number of synapomorphies are identified: sequential sepal initiation with laterals preceding median sepals, retarded petal growth, a (andro)gynophore, the extrastaminal nectary, and stipulate leaves. The peculiar androecium of the Brassicaceae is caused by the strong median compression of the flower, leading to the loss and displacement of median stamens. The derivation of a parietal placenta from an axile placenta is supported. Evidence supports a close link with either Tovariaceae or Capparaceae, concomitant with macromolecular results.Key words: core Brassicales, Capparaceae, Pentadiplandra brazzeana, Tovariaceae, molecular phylogeny, floral development, anatomy, diplostemony, placentation.

Fossil flowers of ericalean affinity from the Late Cretaceous of Southern Sweden

Charcoalified fossil flowers of a new genus and species (Paradinandra suecica) with affinities to Ericales s.l. (sensu lato) are described from the Late Cretaceous (Santonian-Campanian) from Southern Sweden. The flowers are pentamerous, hypogynous, and actinomorphic. Aestivation of sepals and petals is imbricate-quincuncial. The androecium consists of an outer whorl with single episepalous stamens and an inner whorl with paired epipetalous stamens. Pollen is small and probably tricolpate. Three carpels form a syncarpous ovary with numerous campylotropous ovules on parietal placentae. The styles are free for most of their length. The structure of mature fruits and seeds is unknown. Clear distinction of sepals and petals, possible dehiscence of anthers by restricted slits, presence of a nectary, and the general floral construction (salverform corolla) with a canalized access to the floral center clearly indicate insect pollination of the fossil flowers. Comparisons with extant taxa demonstrate that Paradinandra suecica shares many similarities with Ericales s.l. and in particular with members of Ternstroemiaceae, Theaceae, and Actinidiaceae. However, it is neither identical to any one genus of these families nor to any of the previously described ericalean taxa from the Cretaceous and thus provides further evidence of the diversity of Cretaceous ericalean plants.