390 



ILLUSTRATIONS OF THE NATURAL ORDERS. 



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- 

 rcfal 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 Horseradi.>h, 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 tome are ver}' " acrid. Several species are in 



FIG. (190 A Cruciferous flower. C97. The same, with the calyx and corolla removed, show- 

 ing the tetradjnanious stamens. 698. Sj?/fywe5 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 accumbent), 700 The embryo 

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

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

 pilicle of Shepherd's Purse (Capsella Bursa Pastoris). 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 seeds, showing the embryo with the radicle applied to the 

 side of the cotyledon (cotyledons incumbent). 



