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:
Based on historical accounts, rap can be traced back all the way to the time of the griots, who were groups of people from West Africa that delivered stories accompanied by sparse instrumentation and rhythmic drumbeats.