160 \ 



XIII. CRUCIFERjE. 



FIG. 40. 1. A flower of Sinapis nigra. 2. The stamens (4 long and 2 short) and pistil. 3. Plan of the 

 flower, stamens in 2 rows, outer row half wanting. 4. A silique, 5, partly open, showing the septum 

 with seeds attached. e.Cross section of a seed, cotyledons conduplicate (0>. 7. Flower (enlarged) and leal 

 of Capsella. 8. A silicle, 9, open, showing 1 the narrow septum with seeds. 10. Cross section of a seed, 

 cotyledons incumbent (0 U). 11. Section of a winged seed of Arabis Canadensis, cotyledons accumbent II. 



Conspectus of the Genera. 

 * Ornamental exotics not culinary. 



SECTION I. SILICULOSE. ($ 80, note.} 

 I. THLASPI. Dill. 



Gr. j^Xaco, to compress ; on account of the compressed or flattened silicles. 



Calyx equal at base ; petals equal ; silicle short, flat, emarginatc 

 ut the apex, many-seeded ; valves carinate, often winged on the 

 back; cotyledons accumbent (0.-). Lvs. undivided. Fls. white. 



1. T. ARVENSE. Penny Cress. 



Lrs. oblong, coarsely dentate, smooth; silicle roundish-obovate, shorter than 

 the pedicel ; slig. subsessile. In cultivated, stony fields,Can. and Northern States. 

 The whole plant smooth, 8 12' high, branched. Leaves 1 2' long, | as wide, 

 the cauline slightly arrow-shaped with small obtuse auricles, wavy and toothed 



