Polygonum

Century Dictionary and Cyclopedia

1. n. A large genus of plants, type of order Polygonaceæ and tribe Eupolygoneæ. It is characterized by a stem with swollen joints and conspicuous stipular sheaths, flowers with eight or six stamens, two or three styles, and a five-parted and commonly colored perianth, remaining with little change around the black and shining or opaque hard three-angled or compressed nutlet, which is of nearly the same length as the sepals. The species are variously estimated at 150 to 300, widely distributed, and some of them nearly or quite cosmopolitan. They are most abundant in the northern hemisphere, but also extend into arctic, alpine, and tropical regions. Although of polymorphous habit, they are easily distinguished by the swollen joints sheathed with the united stipules. (See cut under node.) Nearly all are herbs, a few shrubby at the base. Some are tall and erect, as P. orientate, the prince's-feather (also called ragged-sailor); a very few are floating, some erect and aquatic, and others climbing or trailing, as P. scandens, now esteemed for baskets in greenhouses, and P. vacinifolium, the rock-knotweed, from the Himalayas, used for ornamental rockeries. The majority are, however, spreading weedy plants, especially in the section Avicularia, a group of about 50 species with wiry and short or prostrate stems, typified by P. aviculare (see knotgrass, doorweed, and bird's-tares), also known by many other names, as allseed, armstrong, beggar-weed, cow-grass, crabweed, goose-grass, iron-grass, knotwort, ninety-knot, pinkweed, sparrow-tongue, swine's-grass. etc. Another section, also of about 50 species. Persicaria, with erect but weak and juicy stems, is typified by the abundant weed P. Persicaria, the lady's-thumb, also called, from the peach-leaf shape of the leaves, persicary and peachwort, from their dark central spot, heart's-ease and spotted knotweed, and, from the jointed stem, crab's-claw and redshanks. Several related species are known as smartweed, especially P. Hydropiper, also called in England redknees, ciderage, lake-weed, etc., and for which see also water-pepper, culrage, and arse-smart. A related and handsomeflowered species of American river-margins, introduced into cultivation as a source of tannin, is P. amphibium, the willow-grass or water-persicaria. The general name knotweed is a book-name for many of the species. Many are mild astringents, others strongly diuretic and acid; the most important in medicine is P. Bistorta (see bistort, snakeweed, adder's-wort, astrology, and dragonwort), also known in England as redlegs, tuice-writhen. Easter-ledges, etc. P.Fagopyrum of many authors, the cultivated buckwheat, is now separated (see Fagopyrum). P. tinctorium is the Chinese indigo-plant, cultivated in France and Belgium, as also in Japan, as a source of a blue dye, a substitute for indigo. The leaves of P. hispidum are used in South America as a substitute for tobacco. For the climbing weed P. Convolvulus, also called cornbind, bearbine, climbing buckwheat, and black bindweed, see ivy-bindweed. For other species, see serpent-grass, jointweed, false buckwheat (under buckwheat), tear-thumb (and cut of leaf under hastate), and scratch-grass. See also cut under ocrea.

Wiktionary

1. n. A taxonomic genus within the family Polygonaceae — including the various knotweeds, smartweeds, and bistort.

GNU Webster's 1913

1. n. (Bot.) A genus of plants embracing a large number of species, including bistort, knotweed, smartweed, etc.

WordNet 3.0

1. n. diverse genus of herbs or woody subshrubs of north temperate regions