Abstract
Three new species of Elatostema (Urticaceae) from Thailand, E.kaweesakii Triyutth. & L.F.Fu, sp. nov., E.rubricaule Triyutth. & L.F.Fu, sp. nov. and E.saxatile Triyutth. & L.F.Fu, sp. nov., are newly described and illustrated. These new species can be distinguished by the presence of rhizome. Elatostemakaweesakii is similar to E.atroviride. Elatostemakaweesakii is a lithophyte growing in limestone crevices. It differs from E.atroviride by its large swollen rhizome, glabrous stem, glabrous receptacle, number of tepal in staminate flower, absence of tepal in pistillate flower, presence of staminodes in pistillate flower and smooth achene. Elatostemarubricaule and E.saxatile are found on sandstone habitats. They have distinct flattened and disk-like rhizome. Elatostemarubricaule is distinguished by its distinct sulcate and reddish stem with flattened and disc-like rhizome and chartaceous leaves with entire margin. Elatostemasaxatile resembles E.bulbiferum but differs by its flattened and disc-like rhizome, acute leaf apex, glabrous receptacle in pistillate inflorescences, presence of staminodes in pistillate flower, and its sandstone habitat. Descriptions, distribution, ecological and phenological data are provided.