. The botany of crop plants : a text and reference book. Botany, Economic. CHAPTER XXH POLYGONACEiE (Buckwheat Family) Herbaceous representatives of this family are largely found in temperate regions, tree- like species in American tropics, while shrubby ones are limited to western Asia. There are about 30 genera and 800 species. Rhubarb and buckwheat are the prin- cipal cultivated members, while a number of species of Rumex (dock), and of Polygo- num (knotweed, bind-weed, etc.) are bad weeds. Stems.—The stems are conspicuously jointed and usually swollen at the joints. The leaves are alternat
. The botany of crop plants : a text and reference book. Botany, Economic. CHAPTER XXH POLYGONACEiE (Buckwheat Family) Herbaceous representatives of this family are largely found in temperate regions, tree- like species in American tropics, while shrubby ones are limited to western Asia. There are about 30 genera and 800 species. Rhubarb and buckwheat are the prin- cipal cultivated members, while a number of species of Rumex (dock), and of Polygo- num (knotweed, bind-weed, etc.) are bad weeds. Stems.—The stems are conspicuously jointed and usually swollen at the joints. The leaves are alternate (Fagopyrum), opposite {Ma- counastrum), or whorled (mountain sorrel, Oxyria digyna). They are mostly entire, rarely lobed or divided. The stipules, with a few ex- cept ions, are membranous, sheathing, and united to form a very characteristic structure, the ocrea (plu. ocreae) (Fig. no).. Fig. 110.—Leaf of common buckwheat (Fagopyrum vulgare). X Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Robbins, Wilfred William, 1884-1952. Philadelphia : P. Blakiston's Son
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