COMPOSITE FAMILY 269 



slightly narrowed above, 5-ribbed; pappus of soft deciduous 

 bristles. — Warm, gravelly soil; occasional around Yosemite 

 Valley and at Moss Creek, Cherry Creek, etc. 



45. TARAXACUM. Dandelion. 

 1. T. officinale Weber. A thick-rooted perennial with 

 lobed leaves all in a basal tuft and large yellow heads on 

 naked hollow stems. Akenes spiny-toothed above and taper- 

 ing to a slender beak. — Occurs in low meadows. 



46. sdNCHUS. Sow-thistle. 

 1. S. asper Hill. Prickly Sow-thistle. A leafy succulent 

 annual, 1 to 3 ft. high, smooth below, pubescent above with 

 gland-tipped hairs. Leaves coarsely lobed and sharp-toothed, 

 the upper sessile and clasping. Flowers yellow. Akenes flat, 

 ribbed, smooth between the ribs; pappus white, cottony. — An 

 introduced weed of wet places. S. oleraceus L., the Common 

 Sow-thistle, may also appear. It is known by the akenes, 

 which are ridged crosswise between the longitudinal ribs. 



47. LACTUCA. Lettuce. 

 1. L. pulchella DC. An erect leafy-stemmed glabrous per- 

 ennial, 1 or 2 ft. high, bearing numerous bluish or violet heads. 

 Leaves lanceolate, entire or backwardly toothed. Akenes very 

 short, flat, tapering to a short beak with abundant soft pappus. 

 — Hetch Hetchy and Yosemite valleys, etc. 



48. TROXIMON. 



Herbs with nearly naked stems, each bearing a single ter- 

 minal head, the leaves all basal or nearly so. Flowers yellow, 

 orange, or purplish. Akenes 10-nerved, tapering to a beak; 

 pappus of numerous soft bristles. 



1. T. glaucum Nutt. Perennial. Leaves 4 to 12 in. long, 

 very variable, entire to deeply lobed. Heads usually purplish 

 or saffron, y 2 to 1 in. long, on stalks 6 to 15 in. high. Akenes 

 narrowed to a thick nerved beak shorter than the body, the 

 pappus rigid. — Meadows above 6000 ft. On high summits the 

 plants are only 2 to 4 in. high (Agoseris monticola Greene). 



2. T. aurantiacum Hook. Like T. glaucum and equally 

 variable, but the akenes tapering into a slender thread-like 

 beak nearly as long as the body, the pappus very soft; flowers 

 orange or purplish. — Moist soil above 5000 ft. alt. T. nuttallii 

 Gray, with similar akenes but yellow flowers, has been re- 

 ported from Yosemite Valley. 



