A foot or two high in tufts, very leafy, the white tufts of woolly hairs rarely becoming tawny. Leaves 2—5 inches long, broadly lanceolate, green above, white-woolly beneath. Heads numerous, ¼ of an inch high in a contracted corymb; involucral bracts numerous, ovate-lanceolate, pearly white, spreading in age. Abundant throughout the region in dry or moist ground and on slopes up to an altitude of 7000 feet; flowering in June and July. [Sidenote: =Carduus Kelseyi= Rydb. _White Thistle._] Stems 18 inches to 4 feet tall, striate, more or less cobwebby-woolly. Leaves linear, sinuately toothed and fringed, with rather weak spines, green above, cottony beneath. Heads several in a leafy spike, 1—1½ inches high, subtended by linear, cut and bristly-fringed and cobwebby-hairy leaves; bracts rather unequal, lanceolate, a few of the outermost with weak spines, the rest unarmed but with a long slender tip; corolla cream-colour. Open ground and on slopes at the lower altitudes throughout the Rockies; flowering in July. [Sidenote: =Carduus undulatus= Nutt. _Wavy-leaved Thistle._] Persistently white-tomentose, 1—3 feet high, branching. Leaves rarely pinnately parted, moderately prickly. Heads of flowers about 1½ inches high, usually solitary at the ends of the branches; principal bracts of the involucre mostly thickened on the back by the broader glandular sticky ridge, comparatively small and narrow, tipped with a short spreading prickle; corollas rose-colour or pale purple. In open grounds throughout the Rockies at the lower altitudes; flowering during July and August. [Sidenote: =Saussurea densa= Hook. _Saussurea._] Nearly smooth, with a decumbent base; 3—12 inches high. Leaves thin, oblong-lanceolate, acuminate, sinuate-dentate, or entire. Heads of flowers several in a compact terminal corymb, involucre campanulate, ½ an inch high; bracts lanceolate, acuminate, nearly equal; corolla purple or violet-blue. On stony slopes or on the moraines at the higher altitudes throughout the Rockies, not common, but frequent in the region around Lake Louise; flowering during July. INDEX