164 FLORA OF PHILADELPHIA. 



20. EAPISTRUM Desv. 



1. Rapistrum rugosum (L.) All. M. p. 460. Ballast and waste plaoea. 

 Summer. 

 Philadelphia— BaUsiSt (He,). Northampton— Easton, Porter (B. C), 

 Camden— Kaighn 'a Point (He.). 



21. DRABA L. Whitlow-grass. 



Petals deeply 2-cleft. 1. D. veriM. 



Petals entire, or rarely toothed. 2, D. CaroUiwina, 



1. Draba verna L. M. p. 460. Sandy places. Early spring. 



2. Draba Caroliniana Walt. M. p. 460. Sandy fields. Spring. 



^ucfcs— Point Pleasant (Fr.). La?ic'as<ej— Lancaster (Ca.). 



Burlington — Burlington, 7. Burlc (He.). Camden — Cooper's Creek near 

 Starrs, Mart. (B. C), Clementon (Br.). Gioacesier— Swedesboro (Li.). 

 Cwm&eWa?id— Vineland (Ab.). Middlesex— ^onWi Amboy (C). Hunter- 

 don— Bull's Island (C). 



22. SOPHIA Adans. Hedge- mustard. 



Pods narrowly linear, 1.5-2.5 cm. long, 1 mm. wide, curved upward ; pedicels 

 ascending. 1. S. Sophia. 



Pods linear-oblong, 5-14 mm. long, 1-2 mm. wide, straight or nearly so. 



2. 8. pinnata. 



1. Sophia Sophia (L.) Britton. M. p. 462. Waste places. Summer. 



Philadelphia— PhiladelTphia Salt Works, /. Burk (He.). 

 Comde7i— Kaighn 's Point (Ja.) (Te.) (Wn.). 



2. Sophia pinnata (Walt.) Britton. M. p. 462. Dry soil. Summer. 



Philadelphia — Ballast (P.). Chester — Banks of the Schuylkill, Dar- 

 lington (Fl. C). 



Cape 3/o2/— Delaware Bay (C). Hunterdon — Hosemont (C). 



23. STENOPHRAGMA Celak. 



1. Stbnophragma Thaliana (L.) Celak. Mouse-ear Cress. M. p. 463. Old 

 fields and rocks. Spring. 



24. ARABIS L. Rock-cress. 



Seeds in 1 row, or in 2 incomplete rows in each cavity of the pod. 



Basal leaves pinnatifid; pods ascending. 1. A. lyrata. 



Basal leaves merely dentate or lyrate. 

 Pods nearly erect, 1 mm. broad. 



Flowers white, 8 mm. broad; pods not appressed; style 1 mm. 



long. 2, A. patens. 



Flowers white or greenish-white, 4-6 mm. broad; pods ap- 

 pressed; style none. 3. A. hirsuta. 

 Pods recurved-spreading. 



Plant glabrous throughout. 4. A. laevigata. 



Leaves and lower part of stem hairy. 5. A. Canadensis. 



Seeds in 2 distinct rows in each cavity of the pod. 6. A. glabra. 



1. Arabis lyrata L. M, p. 463. Rocks and sandy shores. Spring and 



summer. 



2. Arabis patens SuUiv. M. p. 464. Rocky woods. Summer. 



. Bucks— B.ock Hill (,Ta.). Montgomery — Ivj Rock (T^e.) (Wn.). Dela- 



