. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. 555. Xanthium canadenae. yellow in showy heads: leaves various, but spiny on margins, and generally with clasping, auricled bases: bracts of the involucre bristly. S. asper, Hill. Spiny-leaved sow thistle. Annual weed: resembles S. oleraceus closely, but the clasping auricles are rounded at base, stem-leaves not so divided and more spiny. 6. HIERACIUM. Hawkweed. Hairy, or glandular-hispid, or glabrous perennials, with radical or alternate entire leaves: head of 12-20 yellow or orange ligulat
. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. 555. Xanthium canadenae. yellow in showy heads: leaves various, but spiny on margins, and generally with clasping, auricled bases: bracts of the involucre bristly. S. asper, Hill. Spiny-leaved sow thistle. Annual weed: resembles S. oleraceus closely, but the clasping auricles are rounded at base, stem-leaves not so divided and more spiny. 6. HIERACIUM. Hawkweed. Hairy, or glandular-hispid, or glabrous perennials, with radical or alternate entire leaves: head of 12-20 yellow or orange ligulate flowers, solitary or panicled; involucre in one or several series, unequal; rays trun- cate and 5-toothed: achenes oblong, striate, not beaked; pappus single or double, delicate, tawny or brownish, stiff, not plumose. Large number of species widely spread. H. venosum, Linn. Rattlesnake-weed. Smooth, slender, leafless or with 1 or few leaves, 1-2 ft., fork- ing into a loose, spreading corymb of heads: leaves thin, glaucous, radical and tufted, or near base on stem, oblong or oval, nearly entire, slightly petioled or sessile, sometimes purplish or marked with purple veins: achenes linear, not narrowing upward. Dry woods. H. aurantiacum, Linn. Orange hawkweed. Devil's paint-brush. A very bad weed in meadows East, from Europe: hirsute and glandular: leaves narrow: heads deep orange: achenes oblong, blunt. 7. XANTHIUM. Clotbur. Coarse homely annual weeds with large alternate leaves: flowers mon- oecious: in small involucres; sterile involucres composed of separate scales, in short racemes; fertile involucres of united scales forming a closed body, clustered in the leaf-axils, becoming spiny burs. X. canadense, Mill. Common clotbur. Fig. 555. One to 2 ft., branching: leaves broad-ovate, petioled, lobed and toothed: burs oblong-conical, 1 in. long, with 2 beaks. Waste places. X. spinosum, Linn. Spiny clotbur. Pubescent, with 3 spines at the base of each leaf: bur M in. long, with 1
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1913
