18 DIALYPETALOUS EXOGEXS 



Biennial f Stem 6 to 12 or 18 inches high, branched at base, or several from the 

 root. Radical leaves about an inch long, roundish-ovate to obovate-oblong, with a 

 flat petiole. Raceme 2 to 6 inches long. Flowers ochroleucous, or greenish white. 

 Sab. Rocky banks ; Schuylkill : not common. Fl. April. Fr. June. 



f 1 1 Seeds wholly and conspicuously margined. 



3. A. laeyigata, DC. Smooth and glaucous; stem-leaves lance- 

 linear, clasping; siliques recurved-spreading, long and narrow. 

 POLISHED ARABIS. Smooth Rock-Cress. 



Perennial f Stem, 1 to 2 feet high, rather stout, somewhat branched above. Rad- 

 ical leaves 1 to 2 inches long, obovate or oblong, often purplish. Racemes 4 to 8 or 

 10 inches long. Flowers ochroleucous, rather small ; siliques 2 to 3 inches in length. 

 Hob. Low grounds, along Brandy wine : frequent. Fl. April. Fr. June. 



4. A. CanadensiS, L. Stem-leaves oblong-lanceolate, pointed 

 at both ends, sessile, roughish-pubescent ; siliques falcate, pendu- 

 lous. 



CANADIAN ARABIS. Sickle-pod. Turkey-pod. 



Perennial? Stem 2 to 3 feet high, simple, or sparingly branched above, often 

 eparsely hirsute at base. Radical leaves 2 or 3 inches long, obovate or oblong, 

 dying early. Raceme 6 to 10 inches long. Flowers white; siliques 2 to 3 inches 

 long, recurved, the valves veined, and usually ancipital, with a keel-like mid- 

 nerve. 

 Hob. Hilly, open woodlands : frequent. Fl. June. Fr. Aug. 



32. BARBARE V A, R. Br. 



[So named, from having been dedicated to Santa Barbara,] 

 Silique linear, somewhat 4-sided, the valves being strongly keeled 

 by the mid-nerve. Seeds in a single series, not margined. Cotyle- 

 dons flat, thickish. 



1. J5. vulgaris, R. Br. Lower leaves lyrate, the terminal lobe 



rounded ; the upper leaves obovate, often pinnatifid at base ; siliques 



acuminate. 



COMMON BARBAREA. Winter Cress. Yellow Rocket. 



Perennial. Stem 1 to 2 feet high, sulcate-striate, smooth, branched above. Leaves 

 1 to 3 or 4 inches long. Flowers yellow. 

 Hob. Low grounds, along Brandywine. Nat. of Europe. Fl. May. Fr. July. 



Obs. I have no doubt of this being an introduced plant, though 

 quite common in many places. There is a nearly allied species 

 (B. praecox, R. Br.} cultivated around Philadelphia, for the market ; 

 and both are used as a Salad, under the name of "Scurvy-grass," 

 but are, I think, decidedly inferior to Nasturtium. 



TRIBE 2. SISYMBRIE^AE. 



Seeds thickish, ovate or oblong, not margined ; cotyledons plane, with their edges 

 to the septum, incumbent (oj|) i. e. the back of one of them to the radicle. 



33. SISYM'BRIIJM, L. 



[An ancient Greek name ; applied to this genus.] 



Silique subterete, or 4- to 6-sided; valves 1- to 3-nerved. Seeds in 

 a single series, oblong. Mostly annuals. 



1. S. offieinale, Scop. Lower leaves runcinate, upper ones sub- 

 hastate ; racemes slender and virgate ; siliques subulate, subsessile, 

 oppressed to the rachis. 



