BRASSIACEAE. 153 



Pods emarginate ; sinus narrow. 



Rootstock rather slender ; stem 1-2 dm. high ; petals spatulate, about 5 mm. 



long. 2, T. Nuttallii. 



Rootstock stout, densely caespitose ; stems less than i dm. high ; petals broadly 



obovate, 6-y mm. long. 3. T. coloradense. 



Pods truncate or nearly so at the apex ; sinus broad and open. 



Stem 2-3 dm. high ; stem-leaves ample, broader than the basal ones ; sepals 



green. 4. T. glaucum. 



Stems I dm. high or less ; stem-leaves reduced ; sepals and often also petals 



purplish. 5. T. purpurascens. 



1. Thlaspi arvense L. In waste places from Lab. to B. C, N. Y. and Colo. 

 Introduced from Europe. — Alt. 5000-10,000 ft. — Quimby; Silverton; plains 

 and foot-hills near Boulder; Pass Creek. 



2. Thlaspi Nuttallii Rydb. (T. cochleariforme Nutt. ; not DC.) Among 

 rocks in the mountains from Mont, to Wash, and Colo. — Alt. 8000-12,000 ft. — 

 Dead Lake ; Minturn, Eagle Co. ; Bob Creek ; banks of Michigan Creek, near 

 Teller; North Park. 



3. Thlaspi coloradense Rydb. In wet places, among rocks, on the peaks, in 

 Colo. — Alt. 6000-14,400 ft. — Foot-hills, Larimer Co. ; Gray's Peak ; along 

 Beaver Creek ; above timber line, west of Cameron Pass ; Sierra Blanca ; sum- 

 mit of Pike's Peak ; Grand Mesa ; west slope of Bald Mountain ; Clear Creek ; 

 Red Mountain, south of Ouray; Seven Lakes; Los Pinos; Tennessee Pass; 

 Cheyenne Mountain; West Spanish Peak; South Cheyenne Cation; Massif de 

 I'Arapahoe; Spicer, Larimer Co. 



4. Thlaspi glaucum A. Nels. In mountain valleys and canons from Ida. to 

 Colo, and Utah. — Alt. 8000-13,000 ft. — Spring Caiion ; Red Mountain ; Pike's 

 Peak Valley ; Silver Plume ; Gray's Peak ; Bob Creek ; Cameron Pass ; Pass 

 Creek ; near Ironton, San Juan Co. ; Rabbit-Ears, Larimer Co. 



5. Thlaspi purpurascens Rydb. Among rocks, on the peaks of Colo, and 

 Ariz. — Alt. 7000-14,300 ft. — Gray's Peak; Cimarron; Spring Canon; Horse- 

 tooth Gulch; gulch west of Dixon Canon; Rist Caiion; Table Rock; Front 

 Range, Larimer Co.; Dixon Caiion; headwaters of Sangre de Cristo Creek; 

 Iron Mountain; Eldora to Baltimore. 



4. BURSA Weber. Shepherd's Purse. 



i. Bursa Bursa-pastoris (L.) Britton. In waste places and fields from Lab. 

 to Wash, and Calif. — Alt. 4000-9000 ft. — Quimby ; Table Rock ; Ft. Collins ; 

 hills about Box Canon, west of Ouray; Sangre de Cristo Creek; Mancos. 



5. SMELOWSKIA. 



Segments of basal leaves spatulate. j. .S. americana. 



Segments of the basal leaves linear or linear-oblong. 2. 5". lineariloba. 



1. Smelowskia americana Rydb. {S. calycina B. & H. ; not C. A. Mey.) 

 On the higher mountain tops from Mont, to Colo, and Nev. — Alt. 10,000- 

 12,000 ft. — Cumberland Basin, La Plata Mountains ; Devil's Causeway ; moun- 

 tain northwest of Como; Ragged Mountain, Gunnison Co.; Mt. Abram, 

 Ouray. 



2. Smelowskia lineariloba Rydb. On alpine peaks of Colo.— Alt. 12,000- 

 14,000 ft. — Douglass Mountain; Georgetown; Silver Plume; northwest of 

 Como; near Ironton, San Juan Co.; Mt. Bartlett, Robinson. 



