346 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



strongly flattened at a right angle to the partition; seed solitary in 

 each cell. 



Cress (L. sativum), a European species, is grown for greens, and 

 cress-seed oil is obtained from the seeds. The Arizona species are 

 mostly weeds of roadsides and fields. The seeds of L. jremontii 

 and other species were used by the Arizona Indians as food and for 

 flavoring. 



Key to the species 



1. Petals 2 to 3 mm. long, with broad blades and long, narrow claws, much sur- 

 passing the sepals; style conspicuous in fruit (2). 

 2. Stem leaves auriculate and clasping at base, denticulate to sharply dentate; 

 capsules inflated, entire at apex; style in fruit 1 to 1.5 mm. long; plant 



perennial; stems herbaceous above the crown 1. L. draba. 



2. Stem leaves not auriculate and clasping; capsules scarcely inflated, ret use 



at apex; style in fruit barely 1 mm. long or shorter, but at least equaling 



and usually surpassing the very shallow notch of the capsule (3) . 



3. Stems of mature plants woody well above the base; capsules at maturity 



4 to 7 mm. wide, broadly obovoid; plant glabrous, slightly glaucous; 



leaf blades linear, very narrowly lanceolate, or oblanceolate, entire 



or pinnatifid with very few, narrow, entire lobes__ 2. L. fremontii. 



3. Stems not woody or only slightly so at base; capsules less than 4 mm. 



wide (4). 



4. Leaf blades pinnatifid or pinnately toothed; stems soft-pilose or villous, 



seldom merely puberulent 3. L. thurberi. 



4. Leaf blades, at least the uppermost ones, entire; stems puberulent or 



glabrous, rarely short-pilose 4. L. montanum. 



1. Petals less than 2 mm. long, sometimes obsolete; style none or very short, less 

 than 0.3 mm. long, usually not equaling the relatively deep notch of the 

 capsule; plants chiefly annual or biennial; stems never woody (5). 

 5. Pubescence of stiff, spreading hairs; pedicels conspicuously flattened, com- 

 monly about twice as wide as thick; plant diffusely branched from the 

 base; stems decumbent or spreading, seldom erect; blades of the basal 

 leaves deeply cleft or pinnatifid, those of the stem leaves coarsely toothed, 

 cleft, or pinnatifid; capsules commonly short-hirsute or hispid, at least 



on the margin 5. L. lasiocarpum. 



5. Pubescence soft, or more or less appressed, or minute, rarely none; pedicels 

 seldom conspicuously flattened or as much as twice as wide as thick (6). 

 6. Steins prostrate or strongly decumbent; basal leaves often bipinnatifid; 

 stem leaves mostly pinnately parted or divided; sepals usually persist- 

 ent after the petals have fallen, often until the fruit is nearly mature; 



capsules mostly glabrous 6. L. oblongum. 



6. Stems commonly erect or ascending; lower leaves coarsely toothed or cleft, 

 the basal ones sometimes pinnatifid; upper stem leaves narrow, often 

 entire; sepals usually deciduous with the petals (7). 

 7. Petals usually well developed, often surpassing the sepals; pedicels 



spreading soon after anthesis; capsules glabrous 7. L. medium. 



7. Petals shorter than the sepals, commonly not more than half as long, 

 sometimes obsolete; pedicels remaining erect or ascending long after 

 anthesis; capsules glabrous or sparsely pubescent; stems puberulent, 

 pilose, or short-villous 8. L. densiflorum. 



1. Lepidium draba L., Sp. PL 645. 1753. 



Cardaria draba Desv., Jour, de Bot. Desv. 3: 163. 1813. 



Peeples Valley and Jerome Junction, Yavapai County (Loomis 

 6900, McLellan and Stitt 1432), and reported as occurring throughout 

 the State, local at roadsides and in fields and pastures. Introduced 

 from Europe. 



Hoary cress. 



