390 



ILLUSTRATIONS OF THE NATURAL ORDURS. 



peculiar pod. The peculiarity of the stamens is explained, and 

 the singular symmetry of the flower illustrated, on p. 243. All 

 these plants have a peculiar volatile acridity (and often an ethe- 

 real oil, which abounds in sulphur) dispersed through every part, 

 from which they derive their peculiar odor and sharp taste, and 

 their stimulant, rubefacient, and antiscorbutic properties. The roots 

 of some perennial species, such as the Horseradish, or the seeds of 

 annual species, as the Mustard, are used as condiments. In some 

 cultivated plants, the acrid principle is dispersed among abundance 

 of saccharine and mucilaginous matter, affording wholesome food ; 

 as the root of the Turnip and Radish, and the leaves and stalks 



of the Cabbage and Cauliflower. None are really poisonous 

 plants, although some arc very acrid. Several species are in 



FIG. fOG A Cruciferous flower. C97. The same, ivith tho calyx and corolla removed, show- 

 ing the tctradynamous stamens. C98. Silitjues of Arabis Canadensis ; one of them with one of 

 the valves detached, showing the seeds lying on the false partition ; the other valve also falling 

 away. 699. A magnified cross-section of one of the winged seeds, showing the embryo with 

 the radicle applied to the edge of the cotyledons (cotyledons decumbent). 700 The enibrjo 

 detached. 701 The raceme of Draba verna, in fruit 702. A cross-section of one of the «tf- 

 cles, magnified, exhibiting the parietal insertion of the seeds, and the false partition 703. A 

 silicic of Shepherd's Pur.-e (Capsella Bursa Tastoris) 704 The same, with one of the boat- 

 shaped valves removed, presenting a longitudinal view of the narrow partition, &c. 705. A 

 magnified cross-section of one of the seed =, showing the embryo with the radicle applied to the 

 siJo of the cotyledon (cotyledons incumbtnV. 



