vexillar

from The Century Dictionary.

• Pertaining to an ensign or standard.
• In botany, same as vexillary, 2.
• In ornithology, of or pertaining to the vane, web. or vexillum of a feather.

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Of or relating to an ensign or standard.
• adjective botany Of or relating to the vexillum, or upper petal of papilionaceous flowers.