Matelea biflora
Matelea atrostellata
star milkvine, two flower matelea, two-flower milkvine
darkstar milkvine
4–10, decumbent, often branched near base, 7–40 cm, hirsute with long eglandular and minute glandular trichomes.
1–5, twining, often branched near base, 30–200 cm, short-hirsute with spreading to retrorse eglandular and minute glandular trichomes.
1 or 2 colleters on each side of petiole;
petiole 0.5–2.5 cm, hirsute with long eglandular and minute glandular trichomes;
blade ovate to deltate, 0.8–5 × 0.6–3.2 cm, base shallowly to deeply cordate, with 0–2 laminar colleters, apex acute (rounded), surfaces hirsute with long eglandular and minute glandular trichomes, especially so on veins abaxially.
with 1 colleter on each side of petiole;
petiole 0.7–1.7 cm, short-hirsute with eglandular and minute glandular trichomes;
blade ovate to lanceolate, 2.5–5 × 1–3.5 cm, base deeply cordate, with 2–4 laminar colleters, apex attenuate to long-acuminate, surfaces short-hirsute with eglandular and minute glandular trichomes.
solitary, umbelliform, extra-axillary, sessile or subsessile, 1–2-flowered.
solitary, umbelliform to somewhat racemiform, extra-axillary, pedunculate, 1–5-flowered;
peduncle 0–1 cm, short-hirsute with eglandular and minute glandular trichomes.
3–11 mm, hirsute with long eglandular and minute glandular trichomes.
3–10 mm, short-hirsute with eglandular and minute glandular trichomes.
calyx lobes spreading, oval to ovate, 1.8–2.5 mm, apex rounded or acute, hirsute with long eglandular and minute glandular trichomes;
corolla maroon to dark brown, not reticulate, rotate-campanulate, tube 1–1.5 mm, lobes spreading, ovate to narrowly deltate to spatulate, 3–6 mm, margins usually reflexed, pilose to hirsute 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 arching above or incumbent on anthers, equaling or exceeding style apex, maroon to dark brown, 1–1.5 mm, glabrous;
apical anther appendages white, maroon to brown at base, broadly deltoid;
style apex rounded, flat.
calyx lobes spreading, lanceolate, 2–3 mm, apex acute, short-hirsute with eglandular and minute glandular trichomes;
corolla pale to dark maroon or green with maroon tinge, sometimes faintly striate and reticulate towards margins, rotate, tube 1–1.5 mm, lobes spreading, narrowly lanceolate, 5–7 mm, hirtellous abaxially, hirtellous adaxially in ring at base of lobes, vestiture continuing along center of lobes with trichomes diminishing in height (reported to be rarely glabrous);
corona united to corolla and column near base, composed of 5 united segments with outward flared margins, each with an adaxial incurved appendage, crimson to dark maroon, 0.5–1 mm, margins and appendages papillose;
apical anther appendages white, brown at base, deltoid;
style apex concave.
tan to light brown, oval to nearly orbicular or ovate, 8–11 × 7–10 mm, margins broadly winged, chalazal end erose, faces minutely rugose;
coma 2.5–4 cm.
tan, ovate, 8 × 5–6 mm, margins thickly winged, chalazal end minutely erose, faces smooth;
coma 4–5 cm.
not striate, ellipsoid to ovoid, 4.5–8.5 × 1.8–3.5 cm, apex acute, densely muricate (more than 1 protrusion per cm of length), villous to hirsute with long eglandular and minute glandular trichomes.
gray-striate, ellipsoid to lance-ovoid, 8–11 × 1.5–2 cm, apex acuminate, smooth or with very sparse, low tubercules, glabrous.
, herbaceous.
Matelea biflora
Matelea atrostellata
Matelea biflora is occasionally found in grasslands and savannas of the southern Great Plains. It is most common on and around the Edwards Plateau of central Texas, where it occurs in grass-dominated habitats including disturbed areas. The range extends mostly northward and westward of that region to central Oklahoma and extreme eastern New Mexico (Lea County), where the species is much less common. Its conservation status in New Mexico merits evaluation. The plants are covered in short, glandular hairs and are malodorous when touched. The flowers occur most often in pairs, hence the common name two-flowered milkvine.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Matelea atrostellata is endemic to Chihuahuan Desert mountain ranges from the Chinati Mountains to the Sierra del Carmen. Within the flora area, it is uncommon and restricted to Brewster County, Texas, and likely threatened. It is evidently a close relative of M. producta and M. texensis based on similarity in vegetative and fruit characters. However, the flowers diverge dramatically by their rotate corollas with outward-flared, papillose corona segments that are free from the corolla. Like M. texensis, M. atrostellata is found at the southeastern margin of the range of M. producta, and M. atrostellata does not co-occur with either species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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