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. . ii. Z-. ramosissimum. 



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



12. L. divergens. 

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



13. L. densvHorum. 



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. (Thelypodium 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 Carion ; 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 Caiion; 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 Caiion. 



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. 



