 Like "Sabal palmetto", it is a distinct fan palm (Arecaceae tribe Corypheae), with a bare petiole which extends as a center spine or midrib, (costa) 1/2 to 2/3 the length into a rounded, costapalmate fan of numerous leaflets.A costapalmate leaf has a definite costa (midrib) unlike the typical palmate or fan leaf, but the leaflets are arranged radially like in a palmate leaf.All costapalmate leaves are markedly recurved or arched backwards.