Prairie milkvine

Gonolobus cynanchoides Engelmann & A. Gray, Boston J. Nat. Hist. 5: 251. 1845

Herbs. Stems 3–10, ascending to decumbent, often branched near base, 10–70 cm, hirsute with long eglandular and minute glandular trichomes. Leaves with 1 or 2 colleters on each side of petiole; petiole 0.5–1.3 cm, hirsute with long eglandular and minute glandular trichomes; blade ovate to deltate (elliptic or orbiculate), 2.2–5.4 × 1–4.5 cm, base shallowly to deeply cordate, with 0–4 laminar colleters, apex acute to acuminate, surfaces hirsute with long eglandular and minute glandular trichomes, especially so on veins abaxially. Inflorescences solitary, umbelliform, extra-axillary, some appearing terminal, pedunculate, 2–6-flowered; peduncle 0–3 cm, hirsute with long eglandular and minute glandular trichomes. Pedicels 3–5 mm, hirsute with long eglandular and minute glandular trichomes. Flowers: calyx lobes spreading, elliptic (ovate), 2–3 mm, apex acute, hirsute with long eglandular and minute glandular trichomes; corolla green to brown or maroon, not reticulate, rotate-campanulate, tube 0.9–1.2 mm, lobes spreading, planar, deltate to ovate, 2.5–4 mm, glabrous adaxially; corona united to corolla and column near base, composed of 5 united segments forming a ring at base, each with an adaxial incurved appendage incumbent on anthers, exceeded by style apex, green, yellow, or brown, 0.7–1 mm, fleshy, glabrous; apical anther appendages white, maroon to brown at base, rounded-truncate; style apex rounded-conic. Follicles not striate, ovoid to ellipsoid, 5–9.7 × 1.8–3.5 cm, apex acute, sparsely muricate (fewer than 1 protrusion per cm of length), hirsute. Seeds tan to light brown, broadly ovate to nearly orbicular, 10–12 × 9–10 mm, margins broadly winged, chalazal end erose, faces minutely rugose; coma 2.5–3.5 cm.

Flowering Apr–Sep; fruiting May–Oct. Sandy prai­ries, flood plains, stabilized dunes, hillsides, pastures, fields, savannas, pine-oak forests; 10–600 m; Ark., La., Okla., Tex.

Matelea cynanchoides occasionally occurs in sandy grasslands, savannas, and forests of the southern Great Plains. It is more abundant on the Gulf Coastal Plain of southeastern Texas in alluvial deposits overlying sand­stone. The range extends eastward and northward to western Louisiana (Caddo Parish), extreme southwestern Arkansas (Miller County), and central Oklahoma, where the species is limited to deposits of deep sands. At the edge of its range, M. cynanchoides is considered to be of conservation concern in Arkansas and Louisiana. The plants are covered in short, glandular hairs and are malodorous when touched. Matelea cynanchoides is tolerant of disturbance, and resprouted, prostrate plants can be found on roadsides that are subject to regular mowing.