Psilophyta

noun

(Gr. psilos: bare; phyton: plant) A phylum of primitive tracheophyte plants that contains two extant genera - Psilotum (whisk ferns) and Tmesipteris - as well as numerous extinct forms that flourished in the Devonian period. Psilophytes have rhizoids rather than roots; the stems, which show dichotomous branching, may be naked or bear scalelike leaves.