1) Fern 
Pecopteris is a very common form genus of leaves. Most Pecopteris leaves and fronds are associated with the marattialean tree fern Psaronius. However, Pecopteris-type foliage also is borne on several filicalean ferns, and at least one seed fern. Pecopteris first appeared in the Devonian period, but flourished in the Carboniferous, especially the P...
• (n.) An extensive genus of fossil ferns; -- so named from the regular comblike arrangement of the leaflets.
Pe·cop'te·ris noun [ New Latin , from Greek ... to comb + ... a kind of fern.] (Paleon.) An extensive genus of fossil ferns; -- so named from the regular comblike arrangement of the leaflets. 
[n] - Carboniferous fossil fern characterized by a regular arrangement of the leaflets resembling a comb
noun Carboniferous fossil fern characterized by a regular arrangement of the leaflets resembling a comb