Vexillar; Vexillary

Part of speech: noun (n.)

1. Of or pertaining to an ensign or standard.

2. Of or pertaining to the vexillum, or upper petal of papilionaceous flowers. Vexilary æstivation (Bot.), a mode of æstivation in which one large upper petal folds over, and covers, the other smaller petals, as in most papilionaceous plants.