4. Matelea Aubl.
white latex and thus milky sap. Stems 1–3 m long, twining, usually
climbing, branched or unbranched, moderately pubescent with spreading hairs and
also minute glandular hairs (these often dark purple wherever they occur).
Leaves opposite, mostly long-petiolate. Leaf blades ovate to broadly ovate or
nearly circular in outline, less commonly oblong-ovate, the base deeply
cordate, the tip gradually or abruptly tapered to a sharp point, the margins
flat or slightly curled under, the surfaces moderately to densely pubescent
with short hairs and minute glandular hairs. Inflorescences solitary in the
leaf axils, mostly relatively long-stalked, consisting of sometimes branched,
umbellate clusters, with 4–25 flowers. Calyces with the lobes spreading
at maturity, hairy on the outer surface. Corollas more or less spreading to
loosely ascending at flowering (erect in bud and sometimes after flowering),
white to light cream-colored or dark purple to nearly black, hairy on the outer
surface. Gynostegium appearing sessile or nearly so, the corona longer than the
anther/stigma head, modified into a shallow, 5-lobed, cup-shaped crown, with
narrow appendages between the lobes. Fruits pendant, lanceolate to narrowly
ovate in outline, circular or slightly flattened in cross-section (not
noticeably angled), the surface covered with slender, warty, hardened
projections, minutely pubescent, usually with mostly glandular hairs. Seeds
strongly flattened and winged, brown to dark brown, with a tuft of long, silky
hairs at the tip. Two hundred to 250 species, U.S., Mexico, Central America,
South America, Caribbean Islands.
Missouri Matelea sometimes cannot be distinguished from Gonolobus,
although in the latter genus the stems often are more sparsely hairy, and the
frequency of minute glandular hairs is usually far less than in Matelea.
Even species within Matelea cannot be discriminated reliably based only
on vegetative characters.