152 BRASSIACEAE. 



Petals none or minute, scarcely more than half as long as the sepals, linear or 



linear-spatulate. 

 Plant branched at the base ; petals often present. 



Axillary racemes very short and dense, usually shorter than the leaves ; 

 petals more than half as long as the sepals. n. L. ramosissimum. 



Axillary racemes at last elongated ; petals very minute or none. 



12. L. diver gens. 

 Plant simple below, branched above ; petals none ; racemes elongated. 



13. L. densiflorum. 



1. Lepidium spathulatum (Robinson) Vasey. (L. scopulorum spathulatum 

 Robinson) In the mountains of Colo. Between Meeker and Craig; head- 

 waters of Bear Creek. 



2. Lepidium crenatum (Greene) Rydb. (Thely podium crenatum Greene) 

 In river valleys of Colo, and Utah. Paonia; Mancos. 



3. Lepidium montanum Nutt. In mountain valleys and on plains from 

 Wyo. to Wash., Colo, and Ariz.; also in Mex. Alt. 7000-10,000 ft. Pitkin; 

 Lake City. 



4. Lepidium alyssoides A. Gray. In river valleys from Colo, to Tex. and 

 Ariz.; also in Mex. Alt. 5000-8000 ft. Grand Junction; Conejos River, 

 north of Antonito ; Alamosa. 



5. Lepidium Jonesii Rydb. In mountain valleys of Colo, and Utah. Alt. 

 4000-7000 ft. Palisades ; Grand Junction ; Spring Canon ; Montrose. 



6. Lepidium Eastwoodiae Wooton. In river valleys of Colo, and N. M. 

 Alt. 5000-9000 ft. Glenwood Springs ; Sangre de Cristo Creek ; Pueblo Co. 



7. Lepidium idahoense Heller. In sandy river valley in Ida. and Colo. 

 Alt. up to 7000 ft. South of Horsetooth Mountain ; Spring Canon ; foot-hills, 

 Larimer Co. 



8. Lepidium virginicum L. In waste places from Que. to Minn., Fla. and 

 Tex. Alt. 7000-10,000 ft. Along the Conejos River, north of Antonito; 

 Horsetooth Gulch; near Pagosa Peak. 



9. Lepidium medium Greene. In waste places and on sandy soil from Mo. 

 to Tex. and Calif. Alt. 5000-7000 ft. Grand Junction; gulch west of Pen- 

 nock's; Reno; Larimer Co.; plains and foot-hills near Boulder; Lower 

 Boulder Canon. 



10. Lepidium ramosum A. Nels. In arid soil from S. D. to Wyo., Colo, 

 and Utah. Alt. up to 10,000 ft. Vicinity of Como; Wolcott, Eagle Co. 



11. Lepidium ramosissimum A. Nels. In arid soil from Neb. to Wyo. and 

 Colo. Alt. 4000-9000 ft. Pitkin; plains, Colorado Springs. 



12. Lepidium divergens Osterh. In the mountains of Colo. Tennessee 

 Pass. 



13. Lepidium densiflorum Schrad. (L. apetalum Aschers. ; not Willd. ; L. 

 intermedium A. Gray) In waste places and sandy soil from Me. to Alb., DC 

 and Calif. Alt. 4000-9000 ft Quimby; Ft. Collins; New Windsor, Weld 

 Co. ; plains, Larimer Co. ; Arboles ; chaparral-covered hills southeast of 

 Ouray; Dix. 



3. THLASPI L. PENNY-GRASS. 



Pod orbicular in outline, broadly wing-margined and deeply notched at the apex. 



i. T. arvense. 



Pods obovate or cuneate in outline, with narrow margins, truncate or slightly 

 notched at the apex. 



