TETRADYNAMIA. SILIQ.UOSA. 65 



Leaves entire, except in tlie commonest species T, 

 Siirsa past oris, in which the radical ones are pinnatifid, 

 and the sihcle moreover triant^ular and widiout margin; 

 tills was the Capsella of Caesalpinlus, and ought perhaps 

 to he separated from this genus. In the other specits the 

 capsule varies in form, and the cells are also sometimes 

 1-seeded, consequently there is no precision in the arti- 

 ficial character, though there is something in the habit or 

 mode of vegetation which appears to distinguish a Thlaspi. 



Species. 1. T. arvense. A common weed around De- 

 troit, (Michigan Territory.) 2. allinceum 'I'his species 

 sometimes occurs in fields of grain or flax, in such situa- 

 tions I have observed it in the state of Ohio. 3. * Uibero. 

 sum. Silicle suborbiculate, sliorl and compressed; leaves 

 rhomboid-ovate, obsoletely toothed, smooth, and sessile, 

 radical ones upon long petioles; stem pubescent, very 

 sliort and simple; root tuberous and fibrous. Hab. In 

 Western Pennsylvania. P'lowering In April and May. 

 "Not more tlian 4 or 5 inches high; flowers rather large, 

 like those of an Arabis, rosaceous. 4. Bursa pastoris. 



Principally an European genus. 



AoQ. LUNARIA. L. (Moonwort.) 



SlUde entire, elliptic, flat and pedicellatei 

 valves flat, equal with the parallel dissepiment. 

 Two of the leaves of the calix saccate at the 

 base and coloured. 



Leaves simple, the lower ones often opposite. Siliclij 

 very large. 



Species. 1. L. annua. Beginning to be naturalized 

 in several localities around PhiUuldphia; as near Gray's 

 Ferry, Sec. accompanying Chelidonium majus. 



An European genus, its natural limits as yet confined 

 to 2 species. 



Order II.— SILIQUOSA. 



4d7. DENTARIA. L. (Toothwort.) 



SUique springin.^ open elastically and the 

 valves " nerveless" and revolute. JDissepiment 

 partly funejose. 6'%7Tia emarginate. Cato Ion* 

 gitudinally connivent. 



