Matelea biflora |
Matelea edwardsensis |
|
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star milkvine, two flower matelea, two-flower milkvine |
plateau milkvine |
|
Habit | Herbs. | |
Stems | 4–10, decumbent, often branched near base, 7–40 cm, hirsute with long eglandular and minute glandular trichomes. |
1–5, twining, 30–200 cm, sparsely hirsute with short eglandular trichomes to glabrate. |
Leaves | 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 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, extra-axillary, sessile or subsessile, 1–2-flowered. |
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 | 3–11 mm, hirsute with long eglandular and minute glandular trichomes. |
4–10 mm, hirsute with eglandular and inconspicuous glandular trichomes. |
Flowers | 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, 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. |
Seeds | 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. |
brown, ovate, brown, 10–11 × 5–7 mm, margins broadly winged, chalazal end erose; coma 2.5–3 cm. |
Follicles | 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. |
sometimes striate, lance-ovoid to fusiform, 8–10 × 1.5–2 cm, apex acuminate, sparsely to moderately muricate, glabrate. |
Vines | , herbaceous. |
|
Matelea biflora |
Matelea edwardsensis |
|
Phenology | Flowering Mar–Oct; fruiting Apr–Dec. | Flowering Mar–May(–Jun); fruiting Jun–Oct. |
Habitat | Calcareous prairies, hillsides, pastures, fields, savannas. | Hills, slopes, ridges, canyons, limestone, rocky soils, juniper-oak woodlands. |
Elevation | 100–1300 m. (300–4300 ft.) | 100–700 m. (300–2300 ft.) |
Distribution |
NM; OK; TX
|
TX |
Discussion | 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 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 14. | FNA vol. 14. |
Parent taxa | Apocynaceae > Matelea | Apocynaceae > Matelea |
Sibling taxa | ||
Synonyms | Gonolobus biflorus, Chthamalia biflora, G. biflorus var. wrightii | |
Name authority | (Rafinesque) Woodson: Ann. Missouri Bot. Gard. 28: 228. (1941) | Correll: Wrightia 3: 135. (1965) |
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