MUSTARD FAMILY CRUCIFERAE 



The flowers of nearly all species of the Mustard 

 family are characterized by 4 sepals, 4 petals arranged in 

 the form of a cross, 6 stamens 2 of which are shorter than 

 the other 4, and 1 pistil which in fruit becomes a pod. 

 They are so much alike that it is frequently impossible to 

 identify the plants by flowers alone; and the fruits, which 

 often differ enough for purposes of identification, must 

 then be used. 



The family is very important economically, as it con- 

 tains, besides a number of weeds, many beautiful garden 

 flowers and such vegetables as Cabbage, Cauliflower, 

 Kale, Brussels Sprouts, Kohl-rabi, Mustard, Turnip and 

 Radish. No plant in the family is poisonous, but leaves or 

 roots, stems, and in some cases seeds, have a pungent odor 

 or peppery taste. 



KEY TO GENERA 



Flowers yellow 2 



Flowers white or purple • • I 



Petals more than one-half inch long 3 



Petals shorter 4 



Flowers orange-yellow; leaves narrow Erysimum p. 129 



Flowers yellow; leaves broader Brassica p. 12- 



Flowers bright yellow Barbarea p. 131 



Flowers pale yellow Sisymbrium p. i 28 



5. Plants growing in brooks or streams Radicula p. 130 



Plants not in brooks or streams 6 



6. Fruits flat and short 7 



Fruits elongated 8 



Fruits nearly circular, up to one-halt inch in diameter; 



seeds 2 or more in each cell Thlaspi p. 1 25 



Fruits nearly circular, not more than one-eighth inch in 



diameter; seeds i in each cell Lepidium p, 125 



Fruits triangular Capsella p. 1 26 



8. Leaves palmately divided Dentaria p. 133 



Leaves not palmately divided 9 



9. Two of the sepals with a hump just below the tip 



lodanthus p. 132 



Sepals without a hump near the tip 10 



10. Lower leaves nearly as broad as long, on long petioles .... 



Cardamine p. 1 34 



Lower leaves much longer than broad, on short petioles . . . 



irabis p. 1 3 5 



124 



