Morphology of pollen grains of 25 species of Salix (Salicaceae) of the Asian part of Russia according to electron microscopy

This is a study of pollen grain morphology of 25 species of the genus Salix L. (Salicaceae) from of the Asian part of Russia was carried out with the use of scanning electron microscope. All species had 3-colpate pollen grains. The length of the polar axis varied from 14 to 30 mkm, the length of the equatorial diameter - from 9.5 to 17.4 mkm. This study has shown the different shapes of the pollen grains, such as the elliptic, broadly and narrowly elliptic.

MICROMORPHOLOGY OF POLLEN GRAINS FROM BISEXUAL AND FUNCTIONAL MALE FLOWERS OF POMEGRANATE

Modern taxonomy uses pollen grain morphology as an important tool due to itsspecific and diverse features. Pomegranate is an andromonoecious species havingtwo type flowers on the same plant, in other words, hermaphrodite flowers(bisexual) and male flowers (functional male flowers) that develop on the sameplant. The length of polar axis (P) and the equatorial diameter (E) as well as P/Eratio of pollen grains, collected from both bisexual and functionally male flowersof the cultivar ‘Caner I’, were analyzed using scaning electron microscopy (SEM).The length of polar axis (P), the equatorial diameter (E), and P/E ratio wascompared between the two grain. The sculpturing pattern of the exine of both typeflowers was striate, with more parallel longitudinal ridges Pollen from bothbisexual and functional male flower types is similar in size (≈21 μm). In contrast tothe divergent pistil development observed between bisexual and functional malepomegranate flowers, no differences in pollen morphology were detected. Thepollens had prolate shape (P\E=1.65 vs 1.59) in both types of flowers.

Pollen Morphology of Some Species of the Genus Sansevieria Petagna (Asparagaceae)

Pollen grains of 15 species of the genus Sansevieria were examined using light and scanning electron microscopy. The pollen grains were single, but dyads were also found. The basic shape of the pollen grains (with chemical treatment) was subprolate, prolate and prolate-spheroidal and the pollen grains were large (> 50 mm). The pollen grains observed in SEM were prolate-spheroidal, subprolate, prolate and perprolate. The aperture occupied nearly the entire distal hemisphere. The surface of non-apertural areas was microreticulate, psilate-perforate, fossulate and verrucate. The surface of the apertural area was psilate-perforate-verrucate, microreticulate-verrucategemmate and psilate-perforate. The tectum was homogeneous, with perforations. Our results suggest that some species cannot be separated based on pollen grain morphology, but only may be categorized into their groups. The present study investigated pollen grain morphology in eleven species for the first time in terms of pollen micromorphology and provided some important new data.

Pollen development and orbicule and pollen grain morphology in species of Cephalanthus (Rubiaceae-Naucleeae) from the Americas

This paper is the first embryological report on the genus Cephalanthus L. and contributes to future studies in other genera of the tribe Naucleeae. The development of the anther wall in Cephalanthus glabratus (Spreng.) K. Schum. corresponds to the dicot type and microsporogenesis is simultaneous. The young wall of the anther has four layers; epidermis, endothecium, one middle layer and the secretory tapetum. The tissue of the septum has idioblasts with crystalline sand. In the wall of the mature anther, only the endothecium and remnants of epidermal cells were preserved. The occurrence and morphology of orbicules were observed in the mature anthers of all three species of Cephalanthus with scanning electron microscopy. The orbicules have taxonomic value at species level, since these structures allow us to distinguish between the species analysed. The presence of a protruding oncus was observed for the first time in Cephalanthus in non-acetolysed pollen grains. According to our observations, this structure is not affected by the state of anther dehiscence in C. glabratus because the oncus is visible and prominent in the mature pollen grains in both indehiscent and dehiscent anthers.

Ultrastructure and pollen morphology of Bromeliaceae species from the Atlantic Rainforest in Southeastern Brazil

Pollen grain morphology of Bromeliaceae species collected in areas of the Atlantic Rainforest of southeastern Brazil was studied. The following species were analyzed: Aechmea bambusoides L.B.Sm. & Reitz, A. nudicaulis (L.) Griseb., A. ramosa Mart. ex Schult.f., Ananas bracteatus (Lindl.) Schult.f., Billbergia distachia (Vell.) Mez, B. euphemiae E. Morren, B. horrida Regel, B. zebrina (Herb.) Lindl., Portea petropolitana (Wawra) Mez, Pitcairnia flammea Lindl., Quesnelia indecora Mez, Tillandsia polystachia (L.) L., T. stricta Sol., T. gardneri Lindl., T. geminiflora Brongn. and Vriesea grandiflora Leme. Light and scanning electron microscopy were used and the species were grouped into three pollen types, organized according to aperture characteristics: Type I - pantoporate pollen grains observed in P. petropolitana, Type II - 2-porate pollen grains, observed in the genera Ananas, Aechmea and Quesnelia, and Type III - 1-colpate pollen grains, observed in the genera Billbergia, Pitcairnia, Tillandsia and Vriesea. Pollen data led to the construction of an identification key. The results showed that the species analyzed can be distinguished using mainly aperture features and exine ornamentation, and that these characteristics may assist in taxonomic studies of the family.