Any rough or prickly envelope of the seeds of plants, whether a pericarp, a persistent calyx, or an involucre, as of the chestnut and burdock; a seed vessel having hooks or prickles. Also, any weed which bears burs.

A rough or prickly envelope around a seed or fruit

(fruit). A prickly or spiny husk enclosing the seed. (See also Common Fruits.)

Any rough or prickly seed envelope.

a rough or spiny covering of a fruit.

Cypsela enclosed in dry involucre, as in Xanthium.

When the involucre is covered with many barbs.