ABSTRACT
The occurrence of absorptive leaf trichomes is studied in propagules originated from sexual(seeds) and assexual (ramets) reproduction from three terrestrial bromeliads in restinga of Barra de Maricá, Rio de Janeiro, Brazil (22º58´S -42º53´W): Aechmea nudicaulis (L.) Griseb.; Neoregelia cruenta (Graham) L. B. Sm. and Vriesea neoglutinosa Mez. For A. nudicaulis and N. cruenta, theradicle protrusion (germination) occurs in the third day of experiment. The complete expansion of the plumule and emission of the second leaf occur until 15 days after germination. For both species, no absorptive leaf trichomes were detected until day 17 of germination, but several root hairs appear in three days of germination. Results are different for V. neoglutinosa. Although radicle protrusion(germination) occurs inthree days,the events “plumule emission ”and“ expanded plumule with second leaf emission” occurred after 15 and 18 days respectively. For this species, absorptive trichomes were detected yet in the young plumule, but still in the initial phase of differentiation. No root hairs occurred for V. neoglutinosa until the end of the experiment. Absorptive trichomes occurred in the shoot apical meristem from ramets of the studied species. Considering that the seedling phase is very sensible to harsh environments, wesuggest that the occurrence of absorptive trichomes in the very first leaves of ramets, but not on young seedlings, represents an important adaptive capacity for the establishment of terrestrial bromeliads by asexual reproduction under the abiotic conditions of restinga.
Key-words:
Bromeliaceae; sandy coastal plains (restingas); seedling; establishment; ramets; trichomes