Description

Key Characters:

Growth Form: Annual or perennial herbs, sometimes somewhat woody at base.

Stems: Stems usually ± quadrangular, glabrous or variously pubescent.

Roots:

Leaves: Leaves simple. Opposite and decussate (pairs of leaves alternating 90 degrees between nodes) rarely whorled. Margins dentate to variously lobed or pinnatifid. Petiolate or sessile. Stipules absent.

Flowers: Flowers usually numerous in terminal or rarely axillary, usually elongate, indeterminate spikes, each flower subtended by a single small bract. Flowers bisexual (perfect), alternate, nearly zygomorphic. Calyx slightly irregular, usually tubular, 5–angled or 5–ribbed, 5-toothed, the teeth unequal, not accrescent. Corolla slightly irregular, salverform or funnelform, 5-lobed, the lobes somewhat unequal, apex rounded to emarginate. Stamens 4, in 2 pairs, inserted on and included in corolla tube; anthers dithecal, opening by longitudinal slits. Ovary superior, 4-lobed, 2-carpellate, 4-celled, placentation axile; ovules 1 per cell, attached laterally or near base, erect, anatropous; style usually short, 2-lobed, the lobes dissimilar, only 1 stigmatic.

Fruit: Schizocarps readily separating at maturity into 4 linear or oblong–linear; crustaceous nutlets; pericarp hard and dry. Seeds 1 per nutlet; oblong; triangular in cross section; endosperm essentially absent.

Ploidy:

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