410 CICHORIACEAE. 



1. Taraxacum Taraxacum (L.) Karst. (7. officinale Weber.) Around 

 dwellings, in fields and on roadsides from Lab. and Wash, to S. C. and Calif.; 

 naturalized from Europe.— Alt. 4000-7000 ft.— Mintum, Eagle Co.; La Veta; 

 Ft. Collins. 



2. Taraxacum mexicanum DC. In mountain valleys from Colo, to Mex. 

 —Alt. 7000-9000 ft.— Pass Creek; Ouray; headwaters of Sangre de Cristo 

 Creek ; hills southeast of La Veta ; along Uncompahgre River, near Ouray. 



3. Taraxacum dumetorum Greene. (T. oblanceolatum A. Nels.) In moun- 

 tain valleys from Ass. to Colo.— Alt. 7000-10,000 ft.— Columbine ; mountain 

 near Veta Pass ; Cucharas River, below La Veta ; Mancos ; Seven Lakes ; Ft. 

 Collins; Halfway House, Pike's Peak. 



4. Taraxacum leiospermum Rydberg. In the mountains of Colo. — Alt. 

 about 10,000 ft. — Tennessee Pass; Seven Lakes; Cripple Creek. 



5. Taraxacum montanum Nutt. (T. officinale alpinum A. Gray, in part) 

 In the mountains from Mont, to Colo.— Alt. about 9500 ft.— Chambers' Lake; 

 source of Leroux ; Camp Creek. 



6. Taraxacum scopulorum (A. Gray) Rydb. (T. officinale scopulorum A. 

 Gray) On the higher peaks in damp places from B. C. to Utah, Colo, and 

 Mont— Alt. 10,000-13,000 ft.— West Spanish Peak; Mt. Hesperus. 



15. LACTUCA L. Lettuce. 



Achenes with a slender beak ; pappus white. 



Outer bracts (calyculum) not more than half as long as the bracts proper; 

 flowers yellow, rarely tinged with blue. 

 Heads 6-8-flowered ; achenes several-nerved, not rugose ; leaves spinulose 



on the ribs. i. L. virosa. 



Heads 12-20-flowered ; achenes 1-3-nerved, transversely rugose. 



Involucres about i cm. high. 2. L. canadensis. 



Involucres 1.5-2 cm. high. 



Leaves obovate or oblanceolate in outline with broad lobes, often spinu- 

 lose on the mid-ribs beneath. 3. L. ludoviciana. 

 Leaves linear or linear-lanceolate in outline, entire or with narrow lobes, 

 never spinulose. 4- L. graminifolia. 

 Outer bracts gradually increasing inwards ; a distinct calyculum therefore not 

 evident ; flowers blue. 5- L. pulchella. 

 Achenes beakless ; pappus tawny or brown. 6. L. spicata. 



1. Lactuca virosa L. In waste places and fields from Me. and N. D. to 

 Ga. and Calif.; introduced from Europe.— Alt. 5000 ft— Ft. Collins; Poudre 

 flats. 



2. Lactuca canadensis L. In moist open places from N. S. and Sask. to 

 Fla. and Colo.— Alt. 4000-6500 ft.— La Porte, Larimer Co.; Hotchkiss; gulch 

 west of Soldier Canon. 



3. Lactuca ludoviciana DC. River banks and moist places from Minn, and 

 Mont to Mo. and Tex.— Alt. 4000-8000 ft. — New Windsor; between Sun- 

 shine and Ward ; Denver. 



4. Lactuca graminifolia Michx. In rich soil from N. C. and Colo, to Fla. 

 and Ariz.— Alt. up to 7500 ft. — Along the Uncompahgre River, near Ouray. 



5. Lactuca pulchella DC. In wet meadows from Sask. and Wash, to Mo., 

 N. M. and Calif.— Alt. 4000-8000 ft.— Cucharas Valley, near La Veta; Ft 

 Collins; Durango; Clear Creek; Gunnison; Parlin, Gunnison Co.; McCoy; 

 Walsenburg; Montrose; Boulder; Gypsum; Table Rock; Fortification, Routt 

 Co. 



