Fallopia convolvulus (L.) . Lve

Black Bindweed

© DETenaglia

Family - Polygonaceae

Habit - Annual forb with slender taproot, forming mats in open areas or more commonly climbing on adjacent vegetation.

Stems - To 2 m, slender, spreading or climbing, twining, sparsely to moderately pubescent with minute, downwardcurved hairs, occasionally also somewhat mealy. Ocreae 2-4 mm long, oblique at the tip, the surface glabrous or minutely roughened, tan to greenish brown.

	Stem and ocrea.
© SRTurner

Leaves - Alternate, simple, petiolate. Petioles with a deep adaxial groove, retrorse strigose, to 2 cm. Blades 1-7 cm long, 0.8-6.0 cm wide, more or less heart-shaped to ovate-triangular, cordate at the base with the downward-pointing or occasionally spreading basal lobes rounded or pointed, tapered to a sharply pointed tip, the upper surface glabrous, the undersurface minutely roughened and often somewhat mealy, also gland-dotted.

	Stem and leaves.
© SRTurner

	Leaf adaxial.
© SRTurner

	Leaf abaxial.
© SRTurner

	Pressed leaves.
© DETenaglia

Inflorescence - Axillary, spikelike racemes, the flowers 3-6 per fascicle, perfect, the flower stalks 1-3 mm long, not winged, jointed above the midpoint.

	Inflorescence raceme.
© SRTurner

Flowers - Tepals 3-4 mm long at flowering, sometimes becoming enlarged to 4-5 mm at fruiting, those of the inner whorl mostly elliptic, those of the outer whorl obovate, angled to very short-tapered and not decurrent along the stalklike base, glabrous or sparsely and minutely hairy, white, sometimes pinkish-or purplish-tinged toward the base, the outer 3 tepals ridged dorsally or rarely with inconspicuous, slender wings to 0.9 mm wide at fruiting. Styles very short, fused most of their length, the stigmas capitate, entire along the margins. Stamens 6-8, not exserted. Anthers pinkish, bilobed, 0.3 mm broad. Filaments short, white, glabrous, 0.5 mm long. Ovary superior, green, glabrous, 3-angled, 0.7 mm long in flower. Styles 3, partially fused, short, green, glabrous, 0.1 mm long. Stigma green, capitate.

	Flowers and fruits.
© SRTurner

	Fruits, enclosed in persistent perianth.
© DETenaglia

Fruits - Achenes, 3-sided, 2.3-3.5 mm long, the surface dull, appearing finely roughened or with dense, minute tubercles, black.

	Achenes. A distinctive feature of this species is the non-shiny, matte surface of the achenes. Other species in this genus have shiny fruits.
© SRTurner

Flowering - May - November.

Habitat - Bottomland forests, streambanks, bluffs, fields, gardens, railroads, roadsides, disturbed areas.

Origin - Eurasia.

Lookalikes - Fallopia scandens.

Other info. - This species is scattered throughout Missouri, and may be more common than botanical records indicate due to its close resemblance to the very common F. scandens. The two can be distinguished by close examination of the achenes ("seeds"), which have shiny surfaces in the lookalike. Achenes of Fallopia convolvulus are dull in appearance. The plant is common across much of the northern and southwestern U.S., less so in Missouri, and uncommon in the southeast.

The leaves and habit of the plant resembles those of the genus Convolvulus, hence the species epithet. Steyermark wrote that natives used to grind the seeds into flour. The plant is closely related to buckwheat.

Photographs taken off Hwy H, Shannon County, MO., 7-18-03 (DETenaglia); also at Marais Temps Clair Conservation Area, St. Charles County, MO, 7-22-2024 (SRTurner).