Swanflower

Aristolochia longiflora Engelmann & A. Gray

Herbs , erect to sprawling, to 0.25 m. Young stem ribbed, glabrous. Leaves: petiole 0.1-0.8 cm. Leaf blade linear-lanceolate, 10-15 × 0.5-1 cm, base cuneate to attenuate, apex acuminate; surfaces abaxially glabrous to puberulent; venation palmate-pinnate. Inflorescences on new growth, axillary, solitary flowers; peduncle bracteolate, 1-4 cm; bracteoles triangular to lanceolate, to 12 mm. Flowers: calyx brown-purple, curved; utricle angled upward, ovoid to obconic, 1.5 × 0.8 cm; syrinx present, broad and shallow, 1.5 mm; tube curved upward, cylindric, 1-3 × 0.4 cm; annulus absent; limb purple, 1-lobed, lobe strap-shaped, 8 × 1 cm, papillate; gynostemium 5-lobed, cylindric, 5-10 mm; anthers 5; ovary 5-locular, 1-4 cm. Capsule ovoid, 2.5 × 1-3 cm, dehiscence basipetal; valves 5; septa entire, not attached to valves. Seeds flat, triangular, 0.5 × 0.5 cm.

Flowering late spring-summer. Riverbanks, hillsides, chaparral; to 500 m; Tex.; Mexico.