Psilopsida

1 definition found

From WordNet (r) 2.0 [wn]:

  Psilopsida
       n : whisk ferns; comprising the family Psilotaceae or
           Psilotatae: vascular plants with no roots, partial if any
           leaf differentiation, and rudimentary spore sacs [syn: {class
           Psilopsida}, {Psilotatae}, {class Psilotatae}]