76 American Midland Naturalist Monograph No. 7 



28. Camelina Crantz 



l.Stem glabrous; leaves auriculate at base; petals yellow, 5-6 mm 

 long; pods 6-9 mm long, 5-6 mm broad; pedicels 12-25 mm 

 long; an occasional weed in fields and waste places; adv. from 

 Eur. June- July C. sativa (L.) Crantz 



l.Stem hirsute below; leaves sagittate at base; petals pale yellow, 

 3-4 mm long; pods 4-6 mm long, 4-5 mm broad; pedicels 8-15 



mm long; fields and roadsides; nat. from Eur. May-July 



C. rnicrocarpa Andrz. 



29. Cardaria Desv. — Hoary Cress 

 C. draho (L.) Desv. Fields and waste places; nat. from Eur. Apr.- 

 June. [Lepidium draha L.]. 



30. Lepidium L. — Peppercress 

 1. Stem-leaves sessile, not sagittate. 

 2. Pods 2-4 mm long. 



3. Petals conspicuous, white, spatulate, longer than the sepals; 

 waste places, vei-y common. May-Nov. Common Pepper- 

 cress _ L. vhginiciun L. 



3. Petals absent, or minute, linear, much shorter than the sepals; 

 waste places, occasional; nat. from Eurasia. May- July. [L. 

 interjnedinm A. Gray; L. apetalurn sensu auth., non L.] 



L. densiflorum Schrad. 



2. Pods 5-7 mm long; introd. from Eur.; Cook Co. Garden Cress 



L. sativum L. 



1. Stem-leaves sagittate or clasping at base. 



4. Stem-leaves lanceolate, denticulate, grayish puberulent; petals 

 white; pods 5-6 mm long; fields and waste places, common; 



nat. from Eur. May-July. Field Peppercress 



L. carnpestre (L.) R.Br. 



4. Stem-leaves ovate, entire, glabrous, clasping; basal leaves bipin- 

 nate, with linear divisions; petals yellow; pods 4 mm long; 

 waste places, occasional; nat. from Eur. May-June. Clasping 

 Peppercress L. perjoUatinn L. 



31. Thiaspi L. 



T. arvense L. Field Pennycress. Fields and waste places; nat. from 

 Eur. May-Aug. 



32. Capsella Medic. — Shepherd's Purse 

 C. bursa- pastoris (L.) Medic. Fields and waste places, very com- 

 mon; nat. from Eur. Mar.-Oct. 



19. Hypericaceae Lindl. — St. John's-wort Family 

 1. Petals yellow, convolute in the bud; hypogynous glands absent. 



2. Sepals 4, in unequal pairs, the outer pair larger, bract-like; petals 4 



1. Ascyrum 



