Herbs, annual, not rhizomatous, 0.5-1 m. Stems scandent or sprawling, branched proximally, herbaceous, puberulent, sometimes mealy, not glaucous. Leaves: ocrea persistent or deciduous, tan or greenish brown, cylindric, 2-4 mm, margins oblique, face not fringed with reflexed hairs and slender bristles at base, otherwise glabrous or scabrid; petiole 0.5-5 cm, puberulent in lines; blade cordate-ovate, cordate-hastate, or sagittate, 2-6(-15) × 2-5(-10) cm, base cordate, margins wavy, scabrid, apex acuminate, abaxial face usually mealy and, rarely, minutely dotted, not glaucous, adaxial face glabrous. Inflorescences axillary, erect or spreading, spikelike, 2-10(-15) cm, axes puberulent; peduncle 0.1-10 cm or absent, glabrous or scabrid distally in lines. Pedicels ascending or spreading, articulated distally, 1-3 mm, glabrous or, rarely, scabrid. Flowers bisexual, 3-6 per ocreate fascicle; perianth nonaccrescent, greenish white, often with pinkish or purplish base, 3-5 mm including stipelike base, glabrous or outer 3 with blunt, hyaline hairs; tepals elliptic to obovate, apex obtuse to acute, outer 3 obscurely keeled; stamens 8; filaments flattened proximally, glabrous; styles connate distally; stigmas capitate. Achenes included, black, 4-5(-6) × 1.8-2.3 mm, dull, minutely granular-tuberculate, especially on faces; fruiting perianth glabrous or with blunt, hyaline hairs, wings absent or, rarely, flat to undulate, 0.4-0.9 mm wide at maturity, scarcely decurrent on stipelike base, margins entire. 2n = 40.
Flowering May-Oct. Cultivated ground, waste places; 0-2700 m; introduced; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Eurasia; introduced in South America (Argentina, Chile), Africa (Algeria, Morocco, Republic of South Africa), Pacific Islands (Hawaii, New Zealand), Australia.
Fallopia convolvulus can be an aggressive weed in crop fields. Rare plants with winged fruiting perianths have been named var. subalata; that characteristic often varies within populations.
Probably infrequent in all parts of the state, although there are no reports from the southwestern part. A weed mostly of roadsides and fields, and rarely in woodland.
General: Introduced annual, 20-100 cm long; stems twining, climbing to sprawling, usually branched towards the base, puberulent, sometimes mealy; rhizomes absent.
Leaves: Cauline, alternate, cordate-ovate, cordate-hastate, or sagittate, 2-6 cm long, 2-5 cm wide, glabrous above, usually mealy and minutely dotted below, margins entire, wavy, minutely scabrous; ocrea cylindric, 2-4 mm long, papery, tan or greenish brown, glabrous or minutely scabrous; petiole 0.5-5 cm long, puberulent in lines.
Flowers: Inflorescence umbel-like, compound, branched 2-5 times, the branches glabrous or with a tuft of long tangled hairs; bracts of the inflorescence 3 to several, somewhat leaf-like at the lowest node, usually scale-like above; involucre top shaped to campanulate, 1-6 mm long, tomentose to glabrous; perianth 3-7 mm long, bright yellow, the tepals spatulate to obovate, glabrous; flowers April-September.
Fruits: Achene, 3-angled, 4-6 mm long, black, minutely glandular- tuberculate.
Ecology: Roadsides, fields, disturbed habitats; 800-2400 m (2500- 8000 ft); Apache, Cochise, Coconino, Gila, Graham, Greenlee, Maricopa, Mohave, Navajo, Pima, and Yavapai counties; widely distributed throughout North America, Mexico.
Notes: Species of Convolvulus are very similar in leaf shape and habit to F. convolvulus, but are distinguished by the absence of an ocrea (a sheath around the stem formed from fused stipules).
Editor: Springer et al. 2008
Trailing or twining annual to 1 m; stem, petioles, and often the lf-veins scabrellate in lines; lvs sagittate to triangular-cordate, ocreae smooth; racemes interrupted, naked or with a few small lvs at base, 2-6 cm; fls in clusters of 3-6; pedicels 1-2 mm, jointed above; perianth 1.5-2 mm, green outside, white inside; achene dull black, 3-4 mm, closely invested but not exceeded by the perianth; outer tep often with narrowly winged midrib; styles united; 2n=20, 40. Roadsides, railways, and waste ground throughout our range; native of Europe. May-Oct. (Bilderdykia c.; Tiniaria c.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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