Pollen morphology of Chinese Pseudostellaria (Caryophyllaceae) and its systematic significance

The complete chloroplast genome of Pseudostellaria davidii (franch.) Pax, 1934

Pseudostellaria davidii (Franch.) Pax belongs to subseries distancs of Pseudostellaria (Caryophyllaceae), and is mainly distributed in north-eastern Asia. The complete chloroplast (cp) genome of P. davidii was assembled and annotated for the first time in this study. The cp genome of P. davidii is 149,732 bp in length with the GC content of 36.57%, and it consists of four subregions: a large single-copy (LSC) region of 81,156 bp, a small single-copy (SSC) region of 16,894 bp and two inverted repeats (IR) regions of 25,841 bp each. The cp genome of P. davidii encodes a total of 111 unique genes, which are 77 protein-coding genes, four rRNA genes, and 30 tRNA genes. The results of phylogenetic analysis strongly suggested that Pseudostellaria was a monophyletic group and P. davidii forms an independent sister clade to other species of Pseudostellaria.

Pollen morphology of some species of the genus Cephalaria Schrad. (Caprifoliaceae) and its significance for taxonomy

Palynology gives the evidence for identification and elimination of taxonomically complex genera. Pollen morphology of nine species (three subg., three sect.) of the genus Cephalaria Schrad. was studied using light microscopy and scanning electron microscopy. Pollen grains of all investigated species are triporate, suboblate to subprolate (P/E = 0.75-1.28), and large-sized (P = 58.52 μm-114.38, E = 63.84-119.70 μm). The outline of pollen grains in equatorial view is circular or elliptic, in polar view circular, circular-triangular, or triangular. Pores are distinct, lolongate, elliptic, or circular, with an annulus, operculum, and distinct or indistinct, wide halo surrounding the aperture. Exine sculpture is echinate-microechinate or echinate-microechinate-nanoechinate. Additional diagnostic characters at the species level in Cephalaria Schrad. that can be used for the purposes of taxonomy are size of pollen grains and pores, the shape of pores, the width of the annulus, structure of the exine, dimension of echini and microechini, location of microechini, and presence/absence of nanoechini. Palynomorphological data are compared with the taxonomical classification system of investigated taxa. It is shown that pollen grains morphology of the genus Cephalaria Schrad. is similar to the pollen morphology of the genus Dipsacus L., which confirms their inclusion in the Dipsaceae tribe.

Pollen morphology and viability of Tillandsia (Bromeliaceae) species by light microscopy and scanning electron microscopy

Tillandsia is the bromeliad genus containing the largest number of species, with wide geographic dispersion and an important ecological role in the ecosystems. Investigations of pollen morphology are important to support taxonomic and conservation studies as well as to choose promising species for cross-pollination to obtain hybrids. The objective of this study was to evaluate the morphology, production, and viability of pollen grains of 24 Tillandsia species that naturally occur in the state of Bahia, Brazil. Pollen grains were acetolized and analyzed by scanning electron microscopy. The pollen were germinated in vitro in two culture media (BM and BKM) and collected at three floral development stages (pre-anthesis, anthesis and post-anthesis). Pollen viability also was analyzed by staining with Alexander's solution and acetocarmine in three floral development stages. Variations in the ornamentation and size of the pollen were observed among the species studied, with the majority having medium size, while T. polystachia and T. juncea had large grains and the subgenera Diaphoranthema and Phytarrhiza had small grains. The pollen of the majority of species had bilateral symmetry, with a single irregularly shaped colpus, semitectate exine and reticulated-heterobrochate surface. The pollen presented high germination percentage, tube length and viability according to the histochemistry, except for T. recurvata, T. usneoides and T. loliacea. The BKM medium and collection of pollen during anthesis produced the best results for the Tillandsia species. The results can support studies of the taxonomy and conservation of these species, which have great environmental importance and high value for ornamental purposes.