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, 6-7 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. glancum. 



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 Canon ; Massif de 

 1'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 Canon; 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 Canon; Table Rock; Front 

 Range, Larimer Co. ; Dixon Canon ; 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. i. 6". americana. 



Segments of the basal leaves linear or linear-oblong. 2. S. 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. 



