Description
Key Characters:
Growth Form:
Annual or perhaps short-lived perennial herbs.
Stems:
Stems ascending to erect, 5–10 dm long, conspicuously hispid and puberulent in lines.
Roots:
Leaves:
Leaves simple.
Opposite.
Blades deltate–ovate, 2–7 cm long, 0.8–3 cm wide.
Apex acute.
Base truncate to subcordate.
Upper surfaces moderately puberulent; lower surfaces pale, densely puberulent, becoming tomentose.
Margins crenate–serrate, sometimes lower leaves long–ciliate.
Petioles 0.5–2.3 cm long.
Stipules absent.
Flowers:
Flowers (1)3–6 in verticillasters, these arranged in terminal, racemose inflorescences, bracts lanceolate, 3–6 mm long, margins long-ciliate, caducous.
Calyx bilabiate, tubular to campanulate, often tinged purple, 6-9 mm long, cleft nearly 1/2 its length, short hirtellous, 10–15–nerved, upper lip usually concave or arched, entire or 2-toothed, lower lip 2-toothed, sometimes the teeth and lips obsolete.
Corolla scarlet, strongly bilabiate, tube straight or curved 13-17 mm long, upper lip 3.5-5 mm long, subgaleate, entire or 2-lobed, lower lip spreading, 3-lobed; nectary disk often present at base of ovary, annular or developed on anterior side only.
Stamens 2, exserted ca. 3–4 mm beyond corolla tube, aligned with the sinuses; anthers dithecal, opening by longitudinal slits, with an elongate connective articulated near the center of the filament; anther sacs at each end, sometimes lower anther sac or entire lower arm of connective rudimentary.
Ovary superior, 2-carpellate; ovules 1 per ovary lobe, placentation basal-axile; style 1; stigmas 2.
Fruit:
Nutlets 4; 1-seeded; ca. 2.5 mm long.
Seeds with endosperm absent or scanty and oily.
Ploidy:
2n = 20; 22
Habitat:
Naturalized in low elevation; dry; disturbed habitats.
Elevation Range:
50–1,000 m.