This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Annual or perennial often scurfy unarmed twining vines. Leaves alternate, membranous or leathery, cordate or hastate. Ocreae oblique, naked or fringed at the top or the base. Racemes loosely flowered, axillary or terminal, often paniculate, leafy-bracted or naked. Sepals 5, green, white or yellowish, 2 exterior, 2 interior and 1 with one edge interior and one edge exterior, this sepal and the two outer keeled or strongly and conspicuously winged. Pedicels slender, reflexed and articulated. Stamens 8, included; filaments short, converging. Styles 3, short or almost wanting, distinct or rarely united. Achenes 3-angled, dark brown or black, included, smooth and shining or granular and dull. Endosperm horny. Cotyledons accumbent. [Latin, worm, referring to the habit of the plants]
About 8 species, natives of North America and Asia. Type species: Tiniaria Convolvulus (L.) Webb. & Moq.
Outer segments of the calyx unchanged, or keeled in fruit.
Achene granular and dull; ocreae not bristly.
Achene smooth and shining: ocreae bristly.
Outer segments of the calyx conspicuously winged in fruit.
Calyx-wings not incised.
Fruiting calyx 5"-6" long, the wings crisped.
Fruiting calyx 3"-4" long, the wings rather flat.
Polygonum Colvolvulus L. Sp. PI. 364. 1753. T. Convolvulus Webb. & Moq. loc. cit. 1836-40.
Annual, glabrous, scurfy, stem twining or trailing, 6'-3° long, mostly branched, the internodes elongated. Leaves ovate-sagittate or the uppermost lanceolate-sagittate, long-petioled, acuminate at the apex, slightly ciliate, 1/2-3 long; ocreae oblique, short, rough on the margin; axillary clusters or racemes loosely flowered; flowers greenish, pendulous on slender pedicels; calyx 5-parted, closely investing the achene, the outer lobes slightly or not at all keeled; stamens 8; style short, nearly entire; stigmas 3; achene 3-angled, obovoid-pyramidal, 1 1/2" long, thick-pointed, black, granular, rather dull.
In waste and cultivated grounds, nearly throughout North America except the extreme north. Also in the West Indies. Naturalized from Europe. Native of Asia. Sometimes a troublesome weed. Calyx rarely 6-parted. Bearbind. Ivy- or climbing-bindweed. Cornbind. Devil's-tether. Knot- or blackbird-bindweed. July-Sept.