Fringed twinevine

Sarcostemma heterophyllum Engelmann ex Torrey in War Department [U.S.], Pacif. Railr. Rep. 5(2): 362. 1857; Funastrum cynanchoides (Decaisne) Schlechter var. hartwegii (R. W. Holm) Krings; S. cynanchoides Decaisne subsp. hartwegii R. W. Holm; S. cynanchoides var. hartwegii (R. W. Holm) Shinners

Stems glabrous to sparsely puberulent with curved tri­chomes, pilosulose at nodes. Leaves persistent to often caducous, stipular colleter 1 on each side of petiole; petiole 0.2–1.5 cm, pilosulose or puberulent with curved trichomes throughout or in a single line or glabrate; blade linear to linear-lanceolate, 1.5–8 × 0.1–1.5 cm, chartaceous, base hastate, truncate, sagittate, or cor­date, margins plane, apex acute or attenuate, 1-veined or faintly pinnipalmate, surfaces pilosulose to glabrate, margins inconspicuously ciliate with ascending hairs, laminar colleters 0–4. Inflorescences solitary (paired) at nodes, 5–13-flowered; peduncle 0.3–4.5 cm, elongating in fruit, pilosulose to glabrate; bracts caducous, 1, at base of each pedicel. Pedicels 5–14 mm, hispidulous to pilosulose. Flowers: calyx lobes lanceolate, 1.5–2.5 mm, apex acute, erect, hispidulous to pilose, ciliate, colleter 1, in sinuses, or absent; corolla pink to purple with cream margins or cream with pink to purple blotches or streaks, rotate, tube 1–1.5 mm, lobes spreading with ascending tips, ovate, 3.5–5 mm, apex acute to obtuse, pilosulose abaxially, minutely hispidulous adaxially throughout or distally or glabrate, margins ciliate; corona ring green, cream, or pinkish, inflated corona segments proximally green, distally glossy white, ovoid, 1.5–2 mm; style apex shallowly convex. Follicles usually solitary, ovoid to lance-ovoid, 6–9 × 0.6–1 cm, apex long-acuminate, puberulent with curved trichomes. Seeds 20–50, light brown, thickly winged, biconvex, lanceolate, 5–6 × 2–3 mm, convex face coarsely papillate toward chalazal end, concave face nearly smooth; coma white, 2.5–3 cm.

Flowering and fruiting year round. Arroyos, can­yons, hillsides, mountain slopes, old fields, disturbed areas, rocky, gravelly, and sandy soils, alluvium, caliche, limestone, granite, desert scrub, riparian scrub, mesquite scrub, grasslands; 100–1700 m; Ariz., Calif., Nev., N.Mex., Tex., Utah; n, c Mexico.

In the flora region, Funastrum heterophyllum ranges from southern California and extreme southern Nevada, where it co-occurs with F. hirtellum, to the Big Bend region of Texas. It is uncommon in Utah, where its conservation status merits evaluation. Differences between F. heterophyllum and F. hirtellum are discussed under the latter species. Funastrum heterophyllum also encounters F. cynanchoides at sporadic locations from southern Arizona to western Texas. The distinctions between F. heterophyllum and F. cynanchoides are discussed under the latter species. Funastrum heterophyllum is an exceedingly common species of Sonoran Desert arroyos and is also common in the Chihuahuan Desert. During dry periods, its leafless stems form conspicuous tangled masses on arroyo beds and banks, and riparian vegetation. Beginning with R. W. Holm (1950), the epithet hartwegii has been used at the specific and infraspecific levels for this entity. Holm overlooked the lectotypification of Sarcostemma heterophyllum Englemann ex Torrey by A. M. Vail (1897) and typified S. heterophyllum such that it was interpreted as a synonym of F. crispum. M. Fishbein and K. N. Gandhi (2018) showed that the earlier typification by Vail provides priority of F. heterophyllum over other epithets at this rank.