138 SELECTED WESTERN FLORA 



1. A. campestris, Rydb. 



Flowering stems 2-6 in. high; stem leaves bract-like; root leaves obo- 

 vate, without distinct petioles, white-woolly beneath, glabrous or nearly so 

 above; bracts of the fertile heads small, with a brownish spot at the centre, 

 and white at the apex ; bracts of the sterile heads, much larger and herba- 

 ceous throughout. Man. and westward. 



2. A. pulcherrima, (Hook.) Greene. 



Stout, 12-16 in. high; basal leaves oblanceolate, acute, 3-veined; stem 

 leaves lanceolate or linear, acute, getting smaller up the stem; loosely 

 tomentose throughout; bracts brown with dry tips, more acute in the fertile 

 than in the sterile heads. Swampy places, W. Sask. and Alta. 



3. A. media, Greene. 



Low, not 2 in. high, spreading by stolons; leaves spatulate to oblanceo- 

 late, rather acute, gray-woolly on both sides ; bracts of the involucre in 

 fertile heads with sharp tips, those in sterile heads rounded. Rocky Mts. 



4. A. rdsea, (Eat.) Greene. 



Slender, 8 in. to 2 ft. high, sterile branches often ascending or sometimes 

 prostrate; leaves narrowly oblanceolate or spatulate, acute; the whole 

 plant whitish viscid-pubescent; heads in either close or loose clusters; 

 bracts of the involucre in fertile heads rounded, rose color to whitish ; stami- 

 nate plant not known. Alta. 



5. A. paivifolia, Nutt. 



Slender, 8-12 in. high ; stolons about 2J in. long ; whitish-woolly through- 

 out, basal leaves spatulate; stem leaves linear to oblong; heads numerous 

 in an open corymb; bracts in fertile heads acute, those in sterile heads 

 obtuse. (4. microphyllu, Rydb.) Dry plains, Sask. and Al^a. 



6. A. liprica, Greene. 



Usually densely matted, flowering stems seldom more than 6 in. high; 

 whitish-woolly throughout; basal leaves spatulate, narrowed into petioles 

 and rounded at the apex; stem leaves linear, sessile; bracts in the fertile 

 heads obtuse, white or pink often with a brown spot; those in the sterile 

 heads oval and white. (Formerly referred to A. dioica, Gaertn.) S. Man., 

 Sask., and Alta. 



4. CIRSIUM. Common Thistle. 



Heads many-flowered, the flowers all tubular and similar, perfect; 

 bracts of the involucre in many rows, spiny-tipped; receptacle 

 hairy; pappus of numerous long bristles united at the base. Peren- 



