Wavy twinevine

Sarcostemma crispum Bentham, Pl. Hartw., 291. 1849; S. lobatum Waterfall; S. undulatum Torrey

Stems retrorsely puberulent with curved trichomes to gla­brate and puberulent at nodes. Leaves persistent, stipular col­leter 1 on each side of petiole, early-caducous; petiole 0.2–1 cm, puberulent throughout with curved trichomes or in a single line; blade lanceolate to linear-lanceolate (approaching linear), 3–10 × 0.2–3 cm, chartaceous, base cordate, hastate, or truncate, margins strongly to weakly crispate (plane), apex acuminate to attenuate, single-veined to faintly pinnipalmate, surfaces sparsely to densely puberulent with curved trichomes, midvein often conspicuously densely puberulent and whitish, laminar colleters 0–4. Inflorescences solitary at nodes, 4–13-flowered; peduncle 0.5–4.5 cm, puberulent with curved trichomes; bracts caducous, 1, at base of each pedicel. Pedicels 6–25 mm, puberulent with curved trichomes to glabrate. Flowers: calyx lobes lanceolate, 2.5–4 mm, apex acute, erect, puberulent with curved trichomes, colleters 1–2, in sinuses; corolla green or reddish green abaxially, reddish brown, brown, bronze, or green adaxially, rotate-campanulate, tube 2–3 mm, lobes spreading to ascending, ovate, 4–9 mm, apex obtuse, sparsely to densely puberulent abaxially with curved trichomes, glabrous adaxially, margins ciliate; corona ring green to pinkish, inflated corona segments proximally green to magenta, distally glossy white to pink, oblong with medial constriction, 1.5–2.5 mm; style apex convex. Follicles usually solitary, lance-ovoid, 10–13 × 0.6–1.2 cm, apex attenuate, puberulent with curved trichomes. Seeds 20–50, light brown, thickly winged, lanceolate, shallowly naviculate, 8–9 × 3–4 mm, convex face coarsely papillate towards chalazal end, con­cave face nearly smooth; coma white to tawny, 3–3.5 cm. 2n = 44.

Flowering (Mar–)Apr–Aug(–Nov); fruiting May–Nov(–Dec). Hills, plains, cliffs, canyons, arroyos, rocky and sandy soils, limestone, granite, shale, sandstone, gypsum, grasslands, oak, pine-oak, oak-juniper, pinyon-juniper, and mesquite woodlands, chaparral, desert scrub; 200–2100 m; Ariz., Calif., Colo., N.Mex., Okla., Tex.; Mexico.

Typically, Funastrum crispum is easily recognized by its dark green leaves with cordate bases, white venation, and crisped margins; however, plants bearing nearly linear leaves with truncate or hastate bases and planar margins are not uncommon and are easily mistaken for F. heterophyllum if flowers are absent. Funastrum crispum is more typically found in grasslands, whereas F. heterophyllum is more typically found in desert scrub, especially in arroyos. R. W. Holm (1950) lectotypified Sarcostemma heterophyllum Engelmann ex Torrey with Wright 1679, resulting in the synonymy of that name with F. crispum; however, lectotypification of S. heterophyllum was predated by A. M. Vail (1897), who selected Thomas s.n. from Fort Yuma as the type. Consequently, that basionym applies to the species recognized as F. heterophyllum in this treatment (M. Fishbein and K. N. Gandhi 2018). Funastrum crispum is very rare at the edges of its range in California, Colorado, and Oklahoma and is considered to be of conservation concern in those states. The single population in California, in Riverside County, is quite disjunct from the rest of the range of the species.