. Selected western flora : Manitoba, Saskatchewan, Alberta . Botany; Botany; Botany. COMPOSITiB 139 nial or biennial herbs with alternate priokly leaves and large heads of reddish-purple or rarely white flowers. 1. C. unduiatum, (Nutl^.) Spreng. Praihie Thistle. Biennial, whitish-woolly throughout; stem leafy, 1-3 ft. high; leaves partly clasping, pinnatifid, but rarely pinnately divided, somietimes quite prickly; outer bracts of the involucre glandular and glutinous on the back and tipped with spreading prickles; flowers purple or reddish. Prairies, Alta. 2. C. muticum, Michx. Swamp Thi
. Selected western flora : Manitoba, Saskatchewan, Alberta . Botany; Botany; Botany. COMPOSITiB 139 nial or biennial herbs with alternate priokly leaves and large heads of reddish-purple or rarely white flowers. 1. C. unduiatum, (Nutl^.) Spreng. Praihie Thistle. Biennial, whitish-woolly throughout; stem leafy, 1-3 ft. high; leaves partly clasping, pinnatifid, but rarely pinnately divided, somietimes quite prickly; outer bracts of the involucre glandular and glutinous on the back and tipped with spreading prickles; flowers purple or reddish. Prairies, Alta. 2. C. muticum, Michx. Swamp Thistle. Biennial, tall, 2-7 ft. high, smoothish, sparingly leafy; leaves deeply pinnatifid, armed with weak prickles; heads large, few; flowers purple. Swamps and wet prairie, Man. and westward. 3. C. arvensis, (L.) Scop. Canada Thistle. Perennial, from a deep, extensively branching rootstock; stem 'rather slender, 1-3 ft. high, leafy; leaves sinuately pinnatifid and very prickly; heads numerous; flowers rose-purple, or more rarely whitish. A troublesome introduced weed becoming Fig. 83. — Cirsium quite common in cultivated ground. 5. ARCTIUM. Burdock. Heads fairly large, of perfect tubular flowers; corolla purple or white, the tube 5-eleft; receptacle,flat and bristly; involucre almost globular, the bracts stiff and tipped with hooks; pappus of numer- ous scales. Coarse biennial herbs with large alternate leaves, and heads developing into burs clustered at the ends of the branches. 1. A. minus, Bernh. Common Burdock. Stem branched, 2-5 ft. high; leaves large, cordate, on hollow petioles; spines of the outer bracts spreading, those on the inner erect, not so long as the flower. An unsightly weed, common locally about towns. 2. A. LIppa, L. Great Burdock. Larger, 4-9 ft. high, with broader, often cordate leaves, and all the spines on the bracts of the involucre spreading. Waste places about towns. 6. BIGELOWIA. Ratless Goldbnrod. Heads discoid, small, few-flowered, ra
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1915
