Leaf structure of Tillandsia species (Tillandsioideae: Bromeliaceae) by light microscopy and scanning electron microscopy.

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.

Cryopreservation and low-temperature storage of seeds of Tillandsia species (Bromeliaceae) with ornamental potential.

Tillandsia (Bromeliaceae) species have high endemism, and due to their strong ornamental potential, predatory extraction is threatening the extinction or drastic population reduction of many of them. In light of this scenario, it is necessary to find strategies for the conservation of these endangered species. The objective of this study was to evaluate two seed preservation strategies (freezing at - 5 °C and cryopreservation at - 196 °C) for 20 Tillandsia species occurring in the state of Bahia. We initially evaluated the morphometry, thousand-seed weight, and water content, followed by tests of germination and desiccation. After selecting the best result of the germination test (Germitest paper and incubation at 30 °C) and desiccation (3 h on silica gel), we established conservation tests utilizing two temperatures (freezing at - 5 °C and liquid nitrogen at - 196 °C), with storage times of 1, 7, 30, 180 and 450 days. Analysis of variance indicated that the 20 species had different behaviors when submitted to the two temperatures and different storage times. After 450 days there was a reduction in the germination percentage and germination speed index (GSI) of all the species studied when the seeds were preserved in the freezer. The storage in liquid nitrogen was efficient for the preservation of Tillandsia seeds when dried to a moisture content of approximately 7%. Our results support the establishment of a cryobank for Tillandsia to conserve these endemic species.