416 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



6. Agoseris aspera Rydb. Open slopes at Iceberg Lake. B. C, Idaho, and Mont. — 

 Leaves 4 to 7 cm. long, pale; stems 5 to 12 cm. high, hairj^; heads 10 to 15 cm. high, 

 narrow. 



6. Agoseris glauca (Nutt.) Greene. Frequent on the east slope at low altitudes, on 

 open hillsides. B. C. and Wash, to Colo, and S. Dak. (Troximon glaucum Nutt.) — 

 Leaves 8 to 20 cm. long, pale, narrowed to the tip; stems slender, 15 to 30 cm. high, 

 glabrous. 



7. Agoseris scorzoneraefolia (Schrad.) Greene. Frequent on the east slope at low 

 altitudes, on open hillsides or flats; occasionally in alpine meadows. B. C. to Oreg., 

 Colo., and S. Dak. — Leaves oblanceolate or linear-oblanceolate, 10 to 25 cm. long, 

 pale or green, entire or toothed; stems 10 to 40 cm. high, hairy or glabrous; heads 2 

 to 3 cm. high, broad. 



8. Agoseris pumila (Nutt.) Rydb. Exposed rocky slope above Sexton Glacier. 

 Mont, to Colo. {Troximon pumilum Nutt.) — Leaves 3 to 10 cm. long, pale, entire or 

 slightly toothed ; stems mostly 5 to 12 cm. high, hairy or glabrous; heads 1.5 cm. high. 



2. LEONTODON L. Dandelion. 



Perennials with naked hollow stems, each bearing a single head; leaves lobed; 

 flowers yellow; achenes slender-beaked; pappus of numerous soft bristles. 



Achenes red or reddish 1. L. laevigatum. 



Achenes greenish or greenish brown. 



Outer bracts spreading or reflexed 2. L. taraxacum. 



Outer l^iracts appressed. 



Involucre 15 to 18 mm. high 3. L. ceratophorum. 



Involucre 8 to 10 mm. high 4. L. lyratum. 



1. Leontodon laevigatum Willd. Redseed dandelion. Dry slopes at Belton. 

 Widely distributed in N. Amer.; naturalized from Eur. (Taraxacum erythrospermum 

 Andrzej.; T. laevigatuvi DC; L. erythrospermum Eichw.) — Leaves deeply lobed; 

 the lobes triangular; stems 10 to 20 cm. high, slender; heads about 15 mm. high. 



2. Leontodon taraxacum L. Common dandelion. Frequent at low altitudes, 

 especially on the west slope, on open hillsides or in waste ground. Native of Eur.; 

 widely naturalized as a weed in N. Amer. {Taraxacum taraxacum Karst.) — Leaves 

 10 to 30 cm. long, usually with triangular lobes; stems 10 to 30 cm. high; heads 1.5 

 to 2 cm. high. 



3. Leontodon ceratophorum Ledeb. Alpine dandelion. Occasional above tim- 

 ber line, on rock slides or rocky slopes; collected by Umbach on plains at east 

 entrance. Alaska to N. Mex. {Taraxacum montanum Nutt.; T. ceratophorum DC; 

 L. monticola Rydb.) — Leaves 5 to 12 cm. long, toothed or lobed, glabrous; sterna 

 stout, 7 to 20 cm. high. 



4. Leontodon lyratum Ledeb. Rock slide above Ptarmigan Lake. Alaska to 

 Alta. and Colo. {Taraxacum rupestre Greene; T. scopulorum Rydb.; T. lyratum DC; 

 L. rupestris Rydb.; L. scopulorum Rydb.) — Leaves 3 to 8 cm. long, glabrous, with 

 short triangular lobes; stems slender, 2 to 10 cm. high. 



3. LACTUCA L. Lettuce. 



Plants annual, biennial, or perennial, with leafy stems; heads small, numerous, 

 panicled, the flowers blue or yellow; achenes flattened, the pappus of numerous fine 

 soft bristles.- — Cultivated lettuce belongs to this genus. 



Flowers yellow; leaves with fine spiny teeth. Achenes with a slender beak. 



1. L. Tirosa. 



