Tropidogyne euthystyla sp. nov., a new small-flowered addition to the genus from mid-Cretaceous Myanmar amber

Tropidogyne euthystyla, described here, is the fourth species of this fossil genus to have been reported from amber deposits in northern Myanmar. The species are alike in features of the calyx, the shape and venation of the inferior ovary, and the absence of petals. They differ in the number and form of the styles, the lobing of the epigynous disc, and whether the flowers are apparently bisexual or unisexual. In the one species for which several flowers are available for study, T. pentaptera, floral diameters vary from 3.5 to 5.0 mm. The present species, known only from a single flower, is the smallest in the genus, with a floral diameter of only 2 mm. It differs from the 3 previously described species in having 2 stout, erect styles bearing a terminal stigma, whereas the other species have 2 or 3 short or long, arching styles that are decurrently stigmatic along the adaxial surface.

Can fruit ontogenetic features prove to be an important tool in the circumscription of Psychotrieae alliance?

The Rubiaceae tribe Psychotrieae sensu lato and its two largest genera, Psychotria L. and Palicourea Aubl., have been considered taxonomically controversial for a long time. We aimed to identify structural features of the ontogeny of the fruits and seeds with taxonomic potential for the tribe by using species of these two genera, and Rudgea jasminoides (Cham.) Müll.Arg. The samples were obtained from a herbarium and from Brazilian state parks, and sectioned by using a rotation microtome. The fruits were found to be derived from an inferior ovary, and were characterised by a fleshy mesocarp and sclerenchymatic sinuate pyrene. The seeds were pachychalazal and arillate. The fruit was classified as a pomaceous drupoid nuculanium. The investigation showed the utility of some fruit features to discriminate species. Our study also showed that ontogenetic features of fruits and seeds are very homogeneous in Palicourea and Psychotria, which supports the inclusion of both genera in the tribe Psychotrieae.

Chainandra zeugostylus gen. et sp. nov., a mid-Cretaceous amber fossil with sagittate anthers opening widely at maturity

A flower preserved in 100 Ma amber from Myanmar is described here as Chainandra zeugostylus, a new genus and species of fossil angiosperms. The anthers in Chainandra are sagittate at the base and have only a short connective. They dehisce by means of a circumferential stomium, the dorsal and ventral sides of each locule forming flaps that become widely separated. The style of Chainandra is columnar and two-branched above the middle, and the fully inferior ovary bears an epigynous nectar disc but lacks well-defined ribs or veins. In Tropidogyne, Lacknociona, and Strombothelya, similar genera described earlier from the same am-ber deposits, the styles are either unbranched or are 3–5-branched to near the base, and the ovary is half-inferior to inferior, its lower portion often being dis-tinctly veined and ribbed. Morphology of the stamens and gynoecium of the three genera suggests that they are early members of the eudotyledons.

Description of the a species Peliosanthes curviandra (Asparagaceae) from Vietnam with focus on androecium structure and leaf micromorphology

Peliosanthes curviandra is described and illustrated as a new species from southern Vietnam. The new species is characterized by the unusual androecium comprising three erect and curved stamens, perfectly inferior ovary, and a slender tortuous style. The results of observations on the androecium structure and micromorphology of leaf blades were also presented, and the data obtained were briefly discussed in comparison with those known for some other congeners.

Micromorphology and anatomy of the flowers of Galanthus nivalis and Leucojum vernum (Amaryllidaceae)

We studied the structure of flowers of Galanthus nivalis and Leucojum vernum using cross-sections and longitudal sections of permanent preparations using a light microscope. Genera Galanthus and Leucojum belong to the Galantheae tribe characterized by a unique combination of features of the family Amaryllidaceae, i.e. absence of septal nectaries, poricidal anthers and fruit – fleshy capsule. Both species are represented in the flora of Ukraine and have the life form of bulb ephemeroid of decidous forests. Microscopic surveys of flowers are considered as an instrument for determining yet unknown structural adaptations of plants to specialized ways of pollination and determining the first stages of morphogenesis of fruit, because many features of the fruit appear already at the stage of flower. We determined that the tepals of both studied species have multi-bundle traces of 8–9 vascular bundles. Apical dehiscence of the anthers occurs due to short longitudinal sutures in the upper part of the anthers. The nectar disk on the roof of the inferior ovary is poorly differentiated, and has no vascular bundles. We associate the indicated peculiarities of the flower structure with the offer of pollen as the main reward of the pollinator during buzz-polination, which has not reported for the studied species. Placentation is axile in the lower part of the ovary and parietal in the upper one. We consider that the gynoecium of the studied species is eusyncarpous. The vascular system of the inferior ovary is composed of three dorsal and three septal veins, paired ventral bundles of carpels, which form the traces of ovules, and also small additional bundles in the wall of the ovary. For the first time, we have determined the presence of airy parenchyma in the ovules, ovary roof, the style and anthers’ connectives and have confirmed their presence in the tepals and the wall of the ovary at the stage of flowering. We found differentiation of the mesocarp into photosynthesizing and airy parenchyma, small sizes of cells of the endocardium in the area of the dorsal vein, bifurcate dorsal bundles of the carpels, which could be considered as adaptation of different stages of morphogenesis of fruit to dehiscence. Anatomical peculiarities of the ovaries of G. nivalis and L. vernum: numerous vascular bundles in the pericarp, thick parenchyma mesocarp with air-filled cavities, non-lignified endocarp at the stage of the flower we consider adaptations to the formation of fleshy fruit. The new data we obtained on the anatomical structure of the flowers is a significant addition of information about anthecological and carpological (post-anthetic) peculiarities of the surveyed species.

Floral anatomy of Tristerix longebracteatus (Loranthaceae)

Introduction: Most of the New World members of the Loranthaceae comprise a clade that corresponds to the tribe Psittacantheae. Previous studies on floral anatomy and development in this tribe have concentrated on the highly diversified subtribe Psittacanthinae, while the smaller subtribe Ligarineae has received less attention. A detailed anatomical description of Tristerix longebracteatus helps to fill this information gap. Objetive: The present research analyzes the anatomy of Tristerix longebracteatus flowers, detailing the structure of androecium and gynoecium, including megasporogenesis and microsporogenesis. Methodology: Anatomical serial sections of flowers at different stages of development were prepared, following processing with fixation techniques, incorporation in paraffin, microtome sectioning and staining with Astra-blue and basic fuchsin. Results: The large-sized flowers of Tristerix longebracteatus present a complex pattern of vascularization with 18-20 vascular bundles at the base of the inferior ovary. A group of three vascular bundles irrigate the 4-5 petals and associated stamens, and ten bundles continue through the gynoecium. The androecium is composed of four or five anthers with simultaneous microsporogenesis. The gynoecium as a single ovarian cavity with a central mamelon in which the archesporial tissue is oriented towards the style. The base of the style forms a nectary similar to that found in the sister genus Ligaria. Conclusions: The gynoecium with a single ovarian cavity and central mamelon is a condition shared by Tristerix (subtribe Ligarinae) and all the genera of the subtribe Psittacanthinae, except Tripodanthus. The base of the style forms a nectary similar to that found in the sister genus Ligaria. This type of stylar nectary is of taxonomic value for grouping species of the subtribe Ligarinae and difers from the annular nectary of subtribe Psittacanthinae.

Strombothelya gen. nov., a fossil angiosperm with two species in mid-Cretaceous Myanmar amber

Strombothelya, a new genus of fossil angiosperms from Myanmar amber deposits, is represented by 2 flowers that are here described as separate species. Flowers of Strombothelya have 5 spreading, more or less distinctly veined sepals. Petals are absent. There are 10 inwardly arching stamens and a half-inferior ovary, whose broadly conic superior portion terminates in 1 or 3 stout, columnar, apically truncate styles. The superior portion has a papillate surface that was probably nectarifer-ous. The inferior portion of the ovary in both species is obconic and 5- or 10-ribbed. The fossils are comparable in certain respects to the genus Tropidogyne, described earlier from the same amber deposits. The 3 species of Tropidogyne have flowers with 5 or 10 stamens and 2 or 3 slender, curved, acutely-tipped styles. The inferior portion of the ovary is strongly 10-ribbed, while the superior portion is flat or cushion-shaped and bears a lobed nectar-disc. Strombothelya and Tropidogyne inhabited a Cretaceous araucarian rainforest, which may have been located in the Southern Hemisphere continent of Gondwana.

Loropetalum flavum (Hamamelidaceae), a new species from northern Vietnam

Loropetalum flavum (Hamamelidaceae) is described and illustrated as a new species from Bat Dai Son Mountains situated in the northern Vietnam. Recently discovered plant was observed as a typical element of the rich primary forest found on the highly eroded karstic limestone mountain formations allied to the border with China. The new species is characterized by arboreous habit; stellately indumentum of branchlets, leaves and flowers; axillary, capitate, 4–12-flowered inflorescences; yellow, sessile, actinomorphic, bisexual, 4–6-merous flowers with 2-whorled perianth and 2–8 fleshy disc lobes; stamens with conspicuous subulate connective protrusion; anthers with 2 rectangular 2-sporangiate thecae, each dehiscing by 2 valves and syncarpous gynoecium with 2-locular inferior ovary bearing 2 very short separate styles. A key to all known species of Loropetalum species is given and lectotype of L. lanceum is proposed.

Characters of the inferior ovary of Myrteae (Myrtaceae) and their implication in the evolutionary history of the tribe

Myrtaceae is commonly known to have an inferior ovary of appendicular, receptacular or mixed origin. Other characters of the ovary, such as the number of carpels, number of locules, vascularisation pattern, number of ovules, placentation and presence of compitum have also been of interest to researchers aiming to better understand the evolutionary history of the tribe. In the present study, aspects of the structure of the inferior ovary of 21 species of Myrteae are analysed and reviewed as potential characters for better understanding the evolutionary history of Myrteae. Flower buds were embedded in historesin and paraplast and sectioned transversely and longitudinally with a rotary microtome. Results suggested that most species have an inferior ovary of appendicular origin and that a compitum, or compitum tissue, is present in all species analysed, differing only in the degree of development. Number of carpels and locules vary, with most species having two locules. Vascular supply is transeptal and axial, the latter being the most common condition in the investigated species. Data presented here enhance current evolutionary understanding of the tribe and its history. Results indicated that the inferior ovary of ancestral Myrteae may has had an appendicular origin, that the presence and nature of the compitum may have a positive effect on fertilisation efficiency and a relationship with number of ovules and that transepetal vascular supply may be taxonomically useful to define large groups such as Pimenta and Eugenia.