Matelea biflora
Matelea brevicoronata
star milkvine, two flower matelea, two-flower milkvine
shortcrown milkvine
4–10, decumbent, often branched near base, 7–40 cm, hirsute with long eglandular and minute glandular trichomes.
5–20, prostrate, often branched near base, 10–40 cm, hirsute with long 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 or 2 colleters on each side of petiole;
petiole 0.2–0.9 cm, hirsute with long eglandular and minute glandular trichomes;
blade ovate to deltate (lanceolate or orbiculate), 1.1–2.9 × 0.5–2.3 cm, base rounded or truncate (cordate), laminar colleters apparently absent, apex acute to acuminate, surfaces hirsute with long eglandular and minute glandular trichomes, especially so on veins abaxially.
solitary, umbelliform, extra-axillary, sessile or subsessile, 1–2-flowered.
solitary, simple or compound umbelliform, extra-axillary, pedunculate, 2–8-flowered;
peduncle 1.2–7.3 cm, hirsute with long eglandular and minute glandular trichomes.
3–11 mm, hirsute with long eglandular and minute glandular trichomes.
2–6 mm, hirsute with long 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 erect, elliptic, 1.5–2.5 mm, apex acute, hirsute with long eglandular and minute glandular trichomes;
corolla green, faintly to strongly reticulate, campanulate, tube 1–2 mm, lobes spreading to erect, planar, deltate, 1–3 mm, glabrous adaxially;
corona united to corolla and column near base, composed of 2 series, the outer of 5 laminar segments shorter than the style apex, apical margins unlobed, the inner of 5 subulate segments inflexed over the style apex, green or yellow, 0.7–1 mm, glabrous;
apical anther appendages white, green at base, deltoid;
style apex rounded-conic.
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 to light brown, ovate, 10–11 × 7–8 mm, margins broadly winged, chalazal end erose, faces minutely rugose;
coma 2–2.5 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.
not striate, lance-ovoid, 3–6.5 × 1.5–3 cm, apex acute, densely muricate, hirsute.
Matelea biflora
Matelea brevicoronata
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 brevicoronata is uncommon and localized in southern Texas in the vicinity of Laredo (Webb and Zapata counties), on alluvial sands overlying sandstone. Its range is far more restricted than previously thought because variants of M. parviflora (as treated here) with short coronas were included in a broader concept of M. brevicoronata. These species are nearly identical in vegetative characters, and are distinguished only by a combination of floral characters. Compared to M. parviflora, the corollas of M. brevicoronata are campanulate with spreading to ascending lobes that are glabrous adaxially or obscurely hirtellous at the base (versus rotate with spreading to reflexed lobes that are sometimes densely hirtellous adaxially, especially when the lobes are spreading and approaching the orientation of M. brevicoronata). Additionally, the inner corona segments of M. brevicoronata are inflexed over the style apex (versus erect to spreading), and the outer segments lack marginal lobes at the apex (versus minute to more commonly elongate lobes, giving the combined corona segments the appearance of a trident). So far as known, the ranges of the two species approach each other but do not overlap. Because of the highly restricted distribution documented by fewer than ten collections, M. brevicoronata should be considered to be of extreme conservation concern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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