, Keel is the innermost whorl of petals (two smallest anterior petals) found in flowers with vexillary or papilionaceous aestivation. This feature is characteristic of the family Fabaceae (examples given include pea and bean) . By elimination: Tomato belongs to Solanaceae (valvate aestivation) ; Tulip and Aloe belong to Liliaceae (typically valvate aestivation) . Indigofera is a member of Fabaceae.