544 RypBerGc: Rocky MouNTAIN FLORA 
& Garrett 6732 (type, in herb. N. Y. Bot. Gard.); apparently 
also, Salt Lake City, August, 1880, M. E. Jones 1905, and the 
same locality, Sept., 1905, A. O. Garrett 1718. 
- Carduus olivescens sp. nov. 
Perennial; stem slender, somewhat tinged with purple, more or 
less floccose, 4-8 dm. high, leafy; leaves linear in outline, 1-2 dm. 
long, densely white-tomentose beneath, loosely floccose above, 
deeply pinnatifid, with numerous lanceolate, often 2- or 3-cleft 
lobes, ending in short yellow spines; heads few, peduncled, about 
3 cm. high, 3-3.5 cm. wide; bracts slightly floccose on the margins, 
light olive-colored, darker towards the apex, ending in yellow spines 
2-4 mm. long, or the innermost with lance-linear, slightly twisted 
yellowish tips; corollas straw-colored; pappus plumose; tips 
slightly clavate. 
This species was first determined questionably as Carduus 
Tracyi, to which it is not closely related, not having the con- 
spicuous broad glutinous dorsal ridges or the broad bracts of that 
species. In leaf-form it resembles somewhat C. pulcherrimus, 
although the upper surface is more floccose, but otherwise it is 
not close to that species. 
Uran: Aquarius Plateau, August 5, 1905, Rydberg & Carlton 
7450 (type, in herb. N. Y. Bot. Gard.). 
Thistle hybrids are very common in Europe and even tertiary 
hybrids have been reported. No attempt has been made in this 
country to segregate or recognize hybrids in this genus. Asa rule 
specimens of thistles are not so common in herbaria as would be 
expected, probably owing to the difficulty in collecting and pre- 
paring them. 
Thistles are not uncommon in the Rocky Mountains, especially 
in Colorado. No person has perhaps contributed more to the 
knowledge of these plants of that state than Mr. George E. 
Osterhout, of New Windsor, Colorado. He has described a few 
species himself and others have been described from material 
collected by him. There are still more forms recognized by him 
and distributed under manuscript names, but which he has been 
reluctant to describe. With the aid of the material sent me 
by him, augmented by other specimens collected by Baker, Shear, 
Clements, myself, and others, -it has been possible to recognize 
