psilotum nudum (l.) p. beauv. (psilotaceae), a new record for the flora of iran

Specimens of psilotum nudum (l.) p. beauv. were collected in a natural habitat in a program for the collecting of plants and establishment of a herbarium in mazandaran. these specimens were found as epiphyte in the cavities on old trees of parrotia persica (dc.) c.a. meyer. (iron tree) which filled with decomposing plant residues. then available books and flora about the ptredophytes of iran were revised but the species had not been reported. these specimens were later on named psi/otum nudum, which is a new record for the flora of iran. the species is a perennial herb and has branched rhizome and aerial stems with dichotomous branches. foliar appendages are scalelike and onceforked. sporangia are 3locular and 3lobed, occur above the base of forked sporophylls and each lobe exhibits loculicidal dehiscence at maturity.