title: [Various aspects of comparative leaf anatomy of 2 Bromeliaceae (Aechema mexicana Baker and Hechtia glomerata Zucc)].
abstract: The leaf anatomy of two Bromeliaceae, Hechtia glomerata Zucc., a terrestrial xerophyte of arid zones, and Acehmea mexicana Baker, a tropical moist forest epiphyte, is compared; these species show adaptations to different extremes of adverse environmental conditions as to water uptake. The leaves of A. mexicana have more water storage tissue than those of H. glomerata; on the other hand, H. glomerata is capable of root absorption. In A. mexicana, modified nonfunctional stomata increase transpiration resistance. Also, this species shows more specialized foliar trichomes which permit the uptake of water and possibly of nutrients. The balance between transpiration and absorption rates is regulated in both species by the combined presence of peltate scales and stomata. The degree of adaptation to drought presented by epiphytic species is more complicated than that shown by terrestrial species. Epiphytic plants like A. mexicana may be derived from xerophytic species that have undergone readaptation to a humid climate. The conspicuous negative geotropism in the leaves of A. mexicana causes the formation of basal deposits of water, which play an important functional role in survival.
mesh_terms: D010944:Plants / Q000033:anatomy & histology*; D013045:Species Specificity
vernacular_title: Algunos aspectos de anatomía foliar comparada de dos especies de Bromeliaceae (Aechmea mexicana Baker y Hechtia glomerata Zucc)