600 COMPOSITAE (COMPOSITE FAMILY) 



long, with a beak as long or longer. (T. Nuttallii Gray, Proc. Am. Acad. 9: 

 216. 1874; Stylopappus elatus Nutt. 1. c. 433.) From the northwestern part of 

 our range to California and Washington. 



10. Troximon montanum (Osterh.) A. Nels. Perennial from a several- 

 stemmed rootstock; the scapes flowering when about 1 dm. high and elongating 

 to 2.5 or 3 dm., woolly-pubescent beneath the involucre and at the base: 

 leaves oblanceolate, 1-2 dm. long including the narrow-winged petiole, 

 glabrous at the time of flowering or nearly so, entire or some of the larger 

 with few teeth: flowers yellow, the ligules little exceeding the bracts, the 

 fruiting heads about 3 cm. high: involucral bracts woolly-pubescent, es- 

 pecially so on the edges, in three series, the outermost ones lanceolate-acuminate, 

 the second series ovate, acuminate, exceeding the outermost, and equaling the 

 narrow inmost series: achenes 10-striate, a little less than 1 cm. long, tapering 

 into a slender filiform beak of the same length, which is crowned by the bright 

 white pappus of about the same length. T. grandiflorum as to our range. 

 (Agoseris montana Osterh. Bull. Torr. Bot Club 27: 507. 1900.) Colorado 

 and Wyoming. 



107. TARAXACUM Hall. DANDELION 



Perennial acaulescent herbs, with pinnatifid or toothed or rarely entire 

 leaves all in a basal tuft and large heads of yellow flowers terminating usually 

 simple and naked hollow scapes. Principal bracts of the involucre nearly 

 equal, the outer much shorter and in several series. Receptacle flat, naked. 

 Rays 5-toothed at the truncate summit. Achenes oblong or linear-fusiform, 

 4 or 5-angled, 5-10-nerved, somewhat spinulose above, tapering into a slender 

 beak which bears at its summit a copious pappus of unequal persistent bristles. 



Outer calyculate bracts appressed; a diminutive alpine plant . . 1. T. scopulorum. 

 Outer calyculate bracts more or less spreading. 

 Achenes not red. 



Leaves deeply runcinate; outer bracts early reflexed. 



The terminal lobe of leaves large 2. T. officinale. 



The terminal lobe of leaves small . . . . . . 3. T. mexicanum. 



Leaves more or less toothed or sinuate; outer bracts tardily re- 

 flexed or with merely squarrose or reflexed tips. 

 Bracts conspicuously corniculate . . . . . . 4. T. dumetorum. 



Bracts (at least the outer ones) not corniculate . . . 5. T. angustifqlium. 

 Achenes red 6. T. ammophilum. 



1. Taraxacum scopulorum (Gray) Rydb. Mem. N. Y. Bot. Gard. 1: 455. 

 1900. Minute, leaves and scape 3 cm. or less long: hea(} 6 mm. or in fruit 

 even 10 mm. high, narrow, few-flowered; outer involucral bracts lanceolate, 

 rather loose; inner somewhat corniculate. Highest alpine region of the 

 Rocky Mountains, Colorado to Montana. 



2. Taraxacum officinale Weber, Prim. Fl. Hols. 56. 1780. Root thick and 

 long, bitter: leaves oblong or spatulate in outline, irregularly dentate to 

 sinuate-pinnatifid, from a few cm. to nearly 3 dm. long, usually pubescent 

 when young and somewhat succulent: inner bracts of the involucre linear or 

 linear-lanceolate, acute, 10-15 mm. long; outer ones similar but shorter, re- 

 flexed: flowers yellow: pappus brownish or white, maturing into a globose 

 mass. (T. Taraxacum Karst.) COMMON DANDELION. Naturalized from 

 Europe but finding in our range a peculiarly favorable environment, hence 

 overrunning lawns and meadows. 



3. Taraxacum mexicanum DC. Prodr. 7: 146. 1838. Very similar but 

 usually smaller: leaves narrow and the terminal lobe small: bracts few. In- 

 digenous in the mountains; from Wyoming and Utah to Mexico. 



4. Taraxacum dumetorum Greene, Pitt. 4: 230. 1901. Large, the crown 

 of the root, or each of its several branches, bearing mostly 1 stout erect scape 

 1-3 dm. high and several upright leaves, some more than 2 dm. long; herbage 

 glabrous: leaves oblanceolate, acutish, the margin not deeply but very un- 

 evenly and laciniately cut, the teeth spreading, seldom at all runcinate: 

 scape under the involucre arachnoid-tomentose: outer bracts in about 3 series, 



