The fronds of tree ferns are usually very large and multiple-pinnated, but at least one type has entire (undivided) fronds. The fronds of tree ferns also exhibit circinate vernation, meaning the young fronds emerge in coils that uncurl as they grow.he order Cyatheales, which includes the tree ferns, is a taxonomic division of the fern class, Polypodiopsida.
rap noun (MUSIC) A2 [ U ] a type of popular music with a strong rhythm in which the words are spoken, not sung:
(rÄ-pÄlâ²) n. A descent from a height, such as a cliff or wall, in which one slides down an anchored rope and applies friction to control one's speed, either by means of a specialized device or by passing the rope under one thigh and over the opposite shoulder. intr.v. rapÂ·pelled, rapÂ·pelÂ·ling, rapÂ·pels.