An early vascular plant, first known from the Lower Devonian Rhynie Chert, Aberdeenshire, Scotland, and described by R. Kidston and W. H. Lang in a series of papers between 1917 and 1921. Rhynia was a simple, leafless plant with a creeping, horizontal stem (rhizome) from which the upright, aerial shoots arose. The tips of fertile shoots bore oval-shaped sporangia (see spore) and the prostrate, horizontal axis was supported by rhizoids rather than true roots. Originally two species were included in the genus: R. gwynne-vaughanii (up to 20 cm tall) and R. major (20–50 cm). Recent work by David S. Edwards (1986) has shown R. major to vary in its branching pattern from R. gwynne-vaughanii and to lack the tracheids necessary for it to qualify as a vascular plant. Consequently R. major has been transferred to a new genus of uncertain affinity and is now termed Aglaophyton major. See also cooksonia; and psilophytales.
Subjects: Earth Sciences and Geography.