The hidrometric rate of the bark is one of the main elements that influences the settlement of epiphytes on the trunk of trees. Considering there's no information in literature on this subject, for the species in the "caatinga", the extent of absorption of water by the cortex of six species typical of the semi dry region (Salgueiro-PE) was determined. Eight samples of 100 cm², with three repetitions of each species, were collected in healthy adult trees. The samples were placed in a stove (100ºC) for three days, to obtain dry weight. They were kept in saturated atmosphere (UR 90-100%) for four days, weighed, immersed in water (2 days) and weighed again to determine the capacity of the water absorption. For each species, corresponding to weight (g/100cm²) of (1) dehydrated bark, (2) water absorbed in saturated atmosphere and (3) water absorbed after immersion, these values were obtained: Schinopsis brasiliensis Engl, (braúna): (1) 43,15; (2) 7,75; (3) 27,77; Spondias tuberosa Arr. Cam. (umbuzeiro): (1) 17,98; (2) 3,50; (3) 20,97; Bumelia sartorum Mart, (quixabeira): (1) 30,80; (2) 7,17; (3) 46,40; Mimosa hostilis Benth. (jurema-preta): (1) 35,77; (2) 7,63; (3) 29,34; Aspidosperma pyrifolium Mart, (pereiro): (1) 16,36; (2) 2,64; (3) 12,72; Croton sonderianus muell. Arg. (marmeleiro): (1) 13,73; (2) 2,22; (3) 13,53. Considering the water absorbed by the cortex after immersion, the phorophytes were classified as: very xeric ("pereiro', "marmeleiro"), xeric ("umbuzeiro", "braúna", "jurema-preta") and low xeric ("quixabeira").
epiphytes; bark; "caatinga"; hidrometric rate