ALÆ (the plural number) is used to signify those petals or leaves of papilionaceous flowers, placed between those others which are called the vexillum and carina, and which make the top and bottom of the flowers. Instances of flowers of this structure are seen in those of pease and beans, in which the top leaf or petal is the vexillum, the bottom the carina, and the side ones the alæ.