Glossary of Botanical Terms - U

U

umbel

(adjective umbellate) a racemose inflorescence in which all the individual flower stalks arise in a cluster at the top of the peduncle and are of about equal length; in a simple umbel, each stalk is unbranched and bears only one flower; a cymose umbel is an apparent umbel but its flowers open centrifugally.

umbonate

with a conical or blunt projection arising from a flatter surface, as on the top of a mushroom, or in the scale of a pine cone.

uncinate

with a hook at the apex.

undershrub

a low shrub, often with flowering branches that die off in winter; cf. subshrub.

undulate

wavy and not flat; compare sinuate.

unilocular

having one loculus or chamber, e.g., the ovary in the families Proteaceae and Fabaceae.

uniserial

Arranged in a single row or series. Unbranched. Uniseriate.

uniseriate

Arranged in a single row or series. Unbranched. Uniserial.

unisexual

of one sex; bearing only male or only female reproductive organs.

unitegmic

(of an ovule), covered by a single integument.

urceolate

urn-shaped.

utricle

a small bladder; a membranous bladder-like sac enclosing an ovary or fruit; in sedges a fruit in which the pericarp is larger than, and loosely encloses, the seed.