160 



XIII. CRUCIFER^. 



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 aseed, cotyledons conduplicate (0>. 7. Flower (enlarged) and leaf 



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

 cotyledons incumbent (0 ti). 11. Section of a winged seed of Arabis Canadensis, cotyledons acc 



umbent li. 



Conspectus of the Genera. 

 * Ornamental exotics not culinary.' 



SECTION I. SILICTJLOSJE. (^ 80, note.) 



1. THLASPI. Dill. 

 Gr. $A<zw, to compress ; on account of the compressed or flattened silicles. 



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

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

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

 1. T. ARVENSE. Penny Cress. 



L/os. oblong, coarsely dentate, smooth; si'Zicferoundish-obovate, shorter than 

 the pedicel ; stig. subsessile. In cultivated, stony fields,Can. and Northern Stales. 

 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 



