Plateau milkvine

Vines, herbaceous. Stems 1–5, twining, 30–200 cm, sparsely hirsute with short eglandular trichomes to glabrate. Leaves with 1 or 2 colleters on each side of petiole; petiole 1–4 cm, hirsute with eglandular and inconspicuous glandular tri­chomes; blade ovate, 1.5–8 × 1–6 cm, base deeply cordate, basal lobes often overlapping, with 2 laminar colleters, apex acute, surfaces sparsely hirsute with eglandular trichomes, primarily on veins, to glabrate. Inflorescences solitary, umbelliform to racemiform, rarely compound, extra-axillary, pedunculate, 3–12-flowered; peduncle 0.3–1.5 cm, hirsute with eglandular and inconspicuous glandular trichomes. Pedicels 4–10 mm, hirsute with eglandular and inconspicuous glandular trichomes. Flowers: calyx lobes erect, narrowly lanceolate, 2–3 mm, apex acute, hirsute with eglandular and inconspicuous glandular trichomes; corolla pale green to yellow-green with darker green lines along lobes, becoming reticulate at lobe tips, campanulate, tube 2–3 mm, lobes spreading, ovate, 3–4 mm, sparsely hirtellous abaxially, densely hirtellous adaxially; corona united to column near base, of 5 united, fleshy segments free nearly to base, each with an adaxial appendage opposite anthers, apex rounded, yellowish green to pale green, 0.7–1 mm, glabrous; apical anther appendages white, truncate; style apex green, nearly round, flat. Follicles sometimes striate, lance-ovoid to fusiform, 8–10 × 1.5–2 cm, apex acuminate, sparsely to moderately muricate, glabrate. Seeds brown, ovate, brown, 10–11 × 5–7 mm, margins broadly winged, chalazal end erose; coma 2.5–3 cm.

Flowering Mar–May(–Jun); fruiting Jun–Oct. Hills, slopes, ridges, canyons, limestone, rocky soils, juniper-oak woodlands; 100–700 m; Tex.

Matelea edwardsensis is an elusive species with numerous documented localities on and around the east­ern and northern margins of the Edwards Plateau, but it appears to be common nowhere. Superficially, it is very similar to M. reticulata, which is almost invariably pres­ent where M. edwardsensis occurs. Matelea reticulata differs by stems, leaves, and inflorescences that are more densely vestitured with longer trichomes, rotate corollas that are glabrous adaxially and possess lobes nearly orbiculate and with a more reticulate pattern, and a highly reduced corona lacking noticeable lobes. The seeds of M. edwardsensis are also larger and con­spicuously erose at one end. Matelea edwardsensis is frequent across much of its limited range and perhaps not of immediate conservation concern, but its wood­land habitat is increasingly vulnerable to clearing and development.