CRUCIFERjE. 141 



Plate 58. 

 ARABIS, L. 



Siliqua elongata, linearis, compressa, valvis planiusculis 



uninerviis. Semina in locnlis plurima, uniserialia. Cotyle- 



dones planae accumbentes. — Calyx erectus. Petala (alba 



seu rosea) sessilia vel breviter unguiculata, ungue piano. 



Arabis, Linn. Gen. 818. R. Br. in Ait. Kew. 1. c. p. 104. DC. Syst. 2. 

 p. 218. Deless. Ic. 2. t. 24-28. C. A. Meyer, in Ledeb. Fl. 

 Alt. 3. p. 15. Endl. Gen. 4854. 



Rock-Cress. 



Calyx erect : sepals equal, or the two lateral saccate at 

 the base. Petals obovate, spatulate, or oblong, sessile or 

 usually with a short and flat claw. Filaments filiform or 

 subulate, toothless : anthers oblong. Glands 4 to 8. Ova- 

 ry oblong or linear : style usually short or none : stigma 

 truncate or capitate. Ovules numerous on both placentae, 

 pendulous. 



Siliq_ue linear, elongated, compressed, not stipitate, two- 

 valved ; the valves flat or flattish, marked with a prominent 

 midnerve, the sides sometimes minutely veiny : partition 

 destitute of a midnerve ; the areolae oblong or amorphous, 

 and bounded by more or less sinuous or sometimes (in 

 A. Canadensis, laevigata, &c.) exceedingly contorted lines. 

 Seeds numerous, pendulous on filiform and mostly free 

 funiculi, forming a single row in each cell, compressed or 

 flat, with or without a winged margin. Cotyledons flat, 

 parallel with the partition, accumbent against the ascending 

 radicle, which is remote from the placenta. 



Herbs, with annual, biennial, or perennial roots, and 

 leafy steins ; the radical leaves usually petioled, sometime^ 

 lyrate or pinnatifid ; the cauline usually sessile and undi- 

 vided, often sagittate or auriculate at th base. Raceme at 



