unicostate

Related to unicostate: inflorescence, cymose, reticulate venation

u·ni·cos·tate

 (yo͞o′nĭ-kŏs′tāt′)
adj.
Having a single main costa, rib, or riblike part: a unicostate leaf.

unicostate

(ˌjuːnɪˈkɒsteɪt)
adj
(Biology) biology having only one rib or riblike part: unicostate leaves.