ABSTRACT
Tillandsia L. is the largest genus of the family Bromeliaceae, containing 755 species and seven subgenera. Morphoanatomical studies of leaves provide useful characteristics to phylogenetic, taxonomic, and ecological analyses. This study aims to characterize and compare the leaves of 24 species of the four subgenera of Tillandsia that occur in Bahia and also perform adaptative inferences to environmental responses. The results of the species' morphoanatomical studies were compared through dissimilarity analysis. The species have rosulate leaves with varying lengths and widths. The peltate trichomes present variation in the indument density and the length of their wing and central disk. The stomata are longitudinally distributed in one or both sides of the limb. The mesophyll is dorsiventral and presents aquiferous and chlorophyllic parenchymas. The vascular bundles are collateral and partially covered by fibers, except for Tillandsia linearis. Based on the dissimilarity analysis, it was possible to identify the formation of five groups. Group G1 was composed of T. linearis, which diverged from the other species of the subgenus. Group G2 was formed by the remaining species of the subgenus Phytarrhiza. G3 and G4 presented the species of the subgenus Diaphoranthema and Tillandsia, respectively. Group G5 gathered 11 species of the subgenus Anoplophytum and presented higher variability than the other subgenera. Based on the results, the morphoanatomical characteristics can be used to characterize and group Tillandsia species, besides confirming the morphological variability of these species to the epiphyte habit in different environments, especially xeric ones.
Subject(s)
Bromeliaceae , Tillandsia , Animals , Microscopy, Electron, Scanning , Phylogeny , Plant LeavesABSTRACT
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.
