| Noun | 1. | family Rhyniaceae - primitive plants of the Paleozoic fern family - families of ferns and fern allies order Psilophytales, Psilophytales - Paleozoic simple dichotomously branched plants of Europe and eastern Canada including the oldest known vascular land plants genus Rhynia, Rhynia - type genus of the Rhyniaceae; small leafless dichotomously branching fossil plants with terminal sporangia and smooth branching rhizomes genus Horneophyton, Horneophyton - Devonian fossil plant considered one of the earliest forms of vascular land plants; similar to genus Rhynia but smaller |