426 CONTRIBUTIONS FEOM THE NATIONAL, HERBARIUM. 



Rays purple. 

 Tips of the bracts loose and spreading; heads nearly always one on each stem. 



14. E. salsuginosus. 

 Tips of the bracts appressed; heads usually several on each stem. 



Leaves very hairy 15. E. conspicuus. 



Leaves glabrous except on the margins and sometimes on the main veins. 



Bracts with long spreading hairs 16. E. speciosus. 



Bracts minutely hairy and glandular 17. E. macranthus. 



1. Erigeron canadensis L. Horseweed. Occasional in waste or cultivated ground 

 at Belton and about the head of Lake McDonald. Widely distributed in N. Amer. 

 (Leptilon ca7iadenseBritton.) — Annual, 30 to 100 cm. high, very hairy; leaves linear 

 or oblanceolate, 2 to 10 cm. long; heads A^ery numerous, in a long narrow panicle; 

 flowers white. 



2. Erigeron acris L. Rather rare, at low altitudes, in thin woods or on brushy 

 elopes. Alaska to B. C, Colo., Me., and Lab.; also in Eur. and Asia. (E. droebach- 

 ensis Muell. ; E. yellowstonensis A. Nels.)— Biennial or perennial, with hairy or nearly 

 glabrous stems; leaves entire, the lowest ones spatulate or oblanceolate, 5 to 10 cm. 

 long; heads 6 to 8 mm. high, with A'ery short rays. 



A somewhat variable plant, several forms of which are treated by some authors as 

 separate species. The flower heads are inconspicuous. 



3. Erigeron jucundus Greene. Frequent above timber line, in meadows or on rock 

 8 lides or exposed summits ; sometimes found on cliffs or open slopes at middle altitudes . 

 B. C. to Colo, and Que. — Stems finely hairy, often clustered; lowest leaves spatulate, 

 entire, hairy; heads about 6 mm. high, the bracts often purplish; rays very short, pink. 



4. Erigeron unalaschkensis (DC.) Rydb. Rocky slopes at Swiftcurrent Pass. 

 Alaska to Mont., Lab., and Greenl. — Perennial, hairy; leaves 1 to 3 cm. long, spatu- 

 late; heads solitary, 8 to 10 cm. high, the bracts purplish; rays white. 



5. Erigeron compositus Pursh. Cutleaf fleabane. Frequent above timber line, 

 on rock slides and exposed summits; occasional at middle and low altitudes, on exposed 

 slopes. Alaska to Calif., Colo., Sask., and Greenl. — Plants perennial, often in dense 

 tufts; stems naked or with a few linear entire leaves, bearing a single head; basal 

 leaves 1 to 4 cm. long, 1 or 2 times divided, hairy or glabrous ; heads about 7 mm. high ; 

 rays white or pink, sometimes none. 



The glabrous form is E. compositus nudus Rydb. Plants with and without rays 

 often grow side by side. 



6. Erigeron caespitosus Nutt. White fleabane. Frequent on the east slope at low 

 altitudes, on dry rocky hillsides or flats. Yukon to Utah and Colo.^Plants 10 to 15 

 cm. high, densely tufted, finely hairy; leaves oblanceolate, 4 to 10 cm. long, entire; 

 obtuse, 3-nerved; heads 6 to 7 mm. high; rays white, 6 to 10 mm. long. 



7. Erigeron lanatus Hook. Open rocky slopes at Piegan Pass. B. C, Alta., and 

 Mont. — Perennial, loosely tufted, hairy; heads 10 to 12 mm. high, densely white- 

 woolly; rays pale purplish. 



8. Erigeron uniflorus L. Frequent above timber line on rocky slopes or exposed 

 summits. Alaska to Calif., Colo., and Mont.; also in Eur. (E. simplex Greene.) — 

 Plants perennial, 5 to 10 cm. high, hairy; lowest leaves spatulate or oblanceolate, 2 

 to 4 cm. long; heads 8 to 10 mm. high, white-wooll> ; rays pink. 



9. Erigeron leiomerus A. Gray. Moist rocky slopes at Sexton Glacier and Piegan 

 Pass. Alta. to Utah and N. Mex.— Basal leaves spatulate, 2 to 5 cm. long, obtuse; 

 heads 5 to 7 mm. high, the bracts purplish; rays pale purple. 



10. Erigeron nanus Nutt. Moist open slopes at Morning Eagle Falls; rare. Mont, 

 to Colo, and Utah. (E. poliospermus A. Gray.) — Lower leaves linear-oblanceolate, 

 3 to 5 cm. long, obtuse; heads 5 to 7 mm. high; rays pink or white. 



