equitant

a. [ L. equitans, -antis, p. pr. of equitare to ride, fr. eques horseman, fr. equus horse. ] 1. Mounted on, or sitting upon, a horse; riding on horseback. [ 1913 Webster ]

2. (Bot.) Overlapping each other; -- said of leaves whose bases are folded so as to overlap and bestride the leaves within or above them, as in the iris. [ 1913 Webster ]