Vascular Plants of Williamson County

Convolvulus equitans [Convolvulaceae]
texas bindweed

Convolvulus equitans Benth., texas bindweed. Perennial herb, trailing, taprooted but also creeping horizontal, not rosetted, several–stemmed at base, principal branches procumbent (decumbent), < 15 cm tall; shoots with only cauline leaves reoriented to upper side, blades variable, somewhat velveteen and soft–hairy; latex milky.

Stems

Stems cylindric, typical 1.5 mm diameter, tough, green, ± tomentose–velutinous.

Leaves

Leaves helically alternate, simple but typically with a pair of basal lobes, petiolate, without stipules; petiole channeled, to 20 mm long, villous–tomentose with most hairs upward–pointing; blade mostly arrow–shaped with backward–pointing basal lobes but to 5–lobed, < 20—70 × < 15—30 mm, cordate at base with basal lobes to 15 mm long, crenate or with sublobes to entire and often wavy on margins, the teeth and sublobes rounded to obtuse at tips, palmately 3–veined at base and pinnately veined above with principal veins sunken on upper surface and raised on lower surface, with a principal vein to each sublobe or tooth, surfaces ± villous but having fewer hairs on upper surface.

Inflorescence

Inflorescence cyme, (1—)2–flowered, axillary at successive nodes, bracteate; peduncle ascending to spreading, at anthesis to 50 × 1—1.4 mm (the widest just below fork), < leaf, increasing to 60 mm long and wiry in fruit, short–tomentose; bractlet subtending pedicel and at fork bractlets 2 and subopposite, awl–shaped with enlarged base, 1.5—4 mm long, ± short–strigose with upward–pointing hairs, the first bractlet keeled; pedicel of the oldest flower wider but shorter, ca. 10 mm long, with bractlet of future flower at pedicel midpoint.

Flower

Flower bisexual, radial, ca 20 mm across; sepals 5, helically alternate and tightly encircling, outer 2—3 stiff, the outermost 2 sepal roundish and cupped, 7—7.5 × 6 mm, reddish and green, wavy on margin above midpoint, densely short–tomentose to short–strigose (including margins) on exposed surfaces, inner sepals upper portion membranous to scarious, green often tinged purple–red, sepals increasing to 8 mm wide in fruit; corolla broadly and shallowly 5–lobed, ca. 15 mm long, pleated in bud on exposed surface with midveins and dense, ascending stiff hairs; tube and throat narrowly funnel–shaped, white and 5–sided at base (tube) and sericeous white panels and glabrous pink and rose panels; stamens 5, fused to base of corolla decurrent ca. 2 mm; filaments free portion 9—11 mm long, pale purple to white, channeled to above midpoint, glandular–papillate on decurrent base; anthers dorsifixed, dithecal, 1.5—2 mm long, light purple to purple, longitudinally dehiscent; pollen white; nectary disc surrounding base of ovary, 0.3 mm long, 1.5 mm diameter, light yellow, producing nectar; pistil 1, 8.5—13 mm long; ovary conic, 1.5—2 × 1—1.2 mm, greenish white, at top indistinct from style, 2–chambered, each chamber with 2 ovules attached to center; style tapered from ovary, 2–branched, green at base white above, the branches 2.7—3.2 mm long, bladderlike (vesicular).

Fruit

Fruit capsule, loculicidal, 2–valved, 4–seeded, ovoid–subspheroid to broadly obovoid, 5.5—6 × 5.2—7 mm + short beak, pale brown with fine parallel veins; calyx in fruit helically alternate, ovate, outer surface sericeous, margins papery and splitting.

Seed

Seed 3–seeded rounded on back, 3.3—5 × 2.4—4.5 mm, dull dark brown, minutely roughened, with micropyle at base; sepals tightly encircling, to 9 mm long, papery and veiny.

A. C. Gibson