Twining. Winding spirally about a support.
Umbel. An inflorescence in which a cluster of peduncles or pedicels spring from the same point.
Umbellate. In or like an umbel.
Umbellet. A secondary umbel.
Umbonate. Bearing a stout projection in the centre; bossed.
Underleaves. The small accessory leaves or stipules on the under side of the stem in Hepaticæ.
Undulate. With a wavy surface; repand.
Unguiculate. Contracted at base into a claw.
Uni-. In composition, one.
Unisexual. Of one sex, either staminate or pistillate only.