Seed traits favouring dispersal and establishment of six epiphyticTillandsia(Bromeliaceae) species

Abstract There are a number of studies describing the gross range of morpho-anatomical variability in epiphytic Tillandsia species, but the interspecific variation in seed traits remain largely unexplored, although these play an important role in determining dispersal and establishment success. In order to evaluate interspecific variation in seed morphology, anatomy and germination, we sampled six Tillandsia species from the Yucatan peninsula, Mexico, distributed along a precipitation gradient. We studied morpho-anatomical traits (seed length, seed mass, ratio of coma to seed, ratio of embryo to endosperm), seed terminal velocity in still air, and performed histochemical analyses and germination trials under controlled conditions. Tillandsia recurvata differs from the other five species in the structure of the plumose coma; it was the only species lacking an endosperm and showed distinct seedling development. Among the species, bigger seeds were related to longer comas, and had higher germinability. Overall, seed terminal velocity was invariably slow, compared with reports of other anemochorous species, suggesting a high dispersal potential. Taxonomical and ecological implications of our results are discussed.