Matelea parvifolia

Vines, suffrutesent, not corky. Stems 1–10, twining, 10–150 cm, retrorse-puberulent with straight or curved, eglandular trichomes. Leaves with 0–2 colleters on each side of petiole; petiole 0.2–1 cm, sparsely puberulent with curved, eglandular trichomes and inconspicuously glandular-hirtellous; blade ovate to lanceolate or deltate, 0.5–2 × 0.2–1 cm, base truncate to deeply cordate, with 2–4 laminar colleters, apex acute, surfaces hirtellous with eglandular and inconspicuous glandular trichomes. Inflorescences solitary, umbelliform, extra-axillary, sessile, 1–3-flowered. Pedicels 1–5 mm, hirtellous with eglandular and inconspicuous glandular trichomes. Flowers: calyx lobes spreading, deltate to elliptic, 1.9–3 mm, apex acute, hirtellous with eglandular and inconspicuous glandular trichomes; corolla brown or maroon to green, not reticulate, campanulate, tube 0.5–1 mm, lobes erect (spreading), deltate, 2–3 mm, abaxially hirtellous, adaxially hirtellous at base of each lobe to glabrate; corona of 5 united lobes, cup-shaped and undulate-spreading with 5 ridges opposite anthers, exceeded by style apex, maroon or brown to green (yellow), 0.5–0.7 mm, glabrous; apical anther appendages white, deltoid; style apex yellowish green to maroon, pentagonal, head flat to broadly convex. Follicles gray to maroon or purplish striate, narrowly lance-ovoid, 5–9 × 0.5–1.5 cm, apex acuminate, nearly smooth to sparsely tuberculate, mostly on lower half, minutely short-hirsute, glabrate. Seeds tan, ovate, 5–7 × 3–5 mm, margins winged, chalazal end minutely erose, faces rugulose; coma 1.5–2 cm.

Phenology: Flowering and fruiting year round.
Habitat: Hills, slopes, bajadas, canyons, arroyos, often granitic, basaltic, or limestone substrates, rocky or sandy soils, alluvium, desertscrub.
Elevation: 300–1400 m.

Ariz., Calif., Tex., Mexico (Coahuila, Sonora).

Discussion

Matelea parvifolia is a vigorously twining, drought-deciduous vine found disjunctly in the Sonoran and Chihuahuan deserts. To the east, it is restricted to the Big Bend region of Texas and adjacent Coahuila, Mexico. The few collections and observations made in Texas suggest that conservation status in that state merits consideration. The range is much larger in the west, extending from the lower Grand Canyon across the southwestern half of Arizona to adjacent Sonora, Mexico, and southeastern California; these two regions are disjunct by more than 500 km. The absence of M. parvifolia from New Mexico (and Chihuahua, Mexico) is curious, and the species may be sought in the Peloncillo Mountains, as it has been documented just across the border in Sonora. Similarly, discovery in Nevada would not be surprising. As far as known, all reports from Baja California pertain to M. hastulata (A. Gray) Sundell.

The closely related Matelea sagittifolia in southern Texas is nearly identical to M. parvifolia in vegetative characteristics but differs by consistently green corollas with oblong-spatulate lobes (versus shades of brown or maroon and deltate lobes), and a white, lobed style apex (versus green to maroon and pentagonal).

Selected References

None.

Lower Taxa