n. a genus of tall Paleozoic trees superficially resembling modern screw pines; they were structurally intermediate in some ways between cycads and conifers.
n. an order of extinct plants having tall arborescent trunks comparable to or more advanced than cycads; known from the Pennsylvanian; probably extinct since the Mesozoic.
n. an order of extinct plants having tall arborescent trunks comparable to or more advanced than cycads; known from the Pennsylvanian; probably extinct since the Mesozoic.
n. a genus of tall Paleozoic trees superficially resembling modern screw pines; they were structurally intermediate in some ways between cycads and conifers.