Characters.—Flowers naked, hermaphrodite, with a bract on the outside. Stamens 2 or more, arranged on one side, or all round the ovary; to which they adhere more or less; anthers 1—2-celled, with or without a fleshy connective; pollen roundish, smooth. Ovary superior, simple, 1-celled, containing a single erect, orthotropal ovule; stigma sessile, simple, rather oblique. Fruit superior, somewhat fleshy, indehiscent, 1-celled, 1-seeded. Seed erect, with the embryo lying in a fleshy sac, placed at the apex of the seed on the outside of the albumen.—Shrubs or herbaceous plants. Stems articulated. Leaves opposite, verticillate, or alternate, in consequence of the abortion of one of the pair of leaves. Stipules 0, or in pairs, or single and opposite the leaf. Flowers usually sessile, sometimes pedicellate, in spikes which are either terminal or axillary; or opposite the leaves (Lindley).
Properties.—Fruits remarkable for their hot taste, and acrid and stimulant properties. These qualities they owe to the presence of an acrid oil and resin.