CRUCIFERAE. 113 



Family 41. CRUCIFERAE. Mustard Family. 



Herbs, rarely somewhat woody, with watery sap; leaves alter- 

 nate; stipules none; flowers perfect, regular, in usually bractless 

 racemes, spikes or corymbs; sepals 4, usually oblong; petals 4, 

 rarely none, hypogynous, in the form of a cross, equal, generally 

 clawed, alternate with the sepals; stamens 6, rarely fewer, 

 hypognyous, of unequal length, the two shorter opposite the 

 sepals, the four longer opposite the petals; pistil 1, of two united 

 carpels; pod usually 2-celled, dehiscing by the separation of two 

 valves from the central partition, or rarely indehiscent, either 

 much longer than broad (a silique) or short (a silicle). 



Pods indehiscent. 



Fruit winged; pubescence of simple hairs. 155. Thysanocarpus, 114. 



Fruit wingless; pubescence of branched hairs. 156. Athysanus, 114. 

 Pods dehiscent, 2-valved, either elongate (siliques) 

 or short (silicles). 

 Pods elongate (siliques). 



Siliques compressed parallel to the broad 

 partition. 

 Valves nerveless; leaves all petioled. 157. Cardamine, 115. 

 Valves 1-nerved; cauline leaves sessile. 



Siliques lanceolate. 158. Phoenicaulis, 115. 



Siliques linear. 159. Arabis, 115. 



Siliques terete, not at all compressed. 

 Pods 4 cm. long or more. 



Flowers white or red; stigmas entire; 



pods erect. 160. Thelypodium, 117. 



Flowers yellow; stigmas 2-lobed; 

 pods spreading. 

 Flowers large; leaves nearly en- 

 tire. 161. Erysimum, 117. 

 Flowers small; leaves pinnatifid. 164. Sisymbrium, 119. 



Pods less than 4 cm. long. 



Siliques beaked; seeds globose. 162. Brassica, 118. 



Siliques beakless; seeds oblong. 



Valves of the pods nerveless. 163. Radicula, 118. 

 Valves of the pods nerved. 



Annuals; leaves pinnate or 



pinnatifid. 164. Sisymbrium, 119. 



Perennials; leaves lyrate. 165. Campe, 120. 



Pods short (silicles). 



Silicles compressed parallel to the partition. 

 Flowers solitary on scapes, white; seeds 



winged. 166. Platyspermum, 120. 



Flowers racemose; seeds wingless. 



Silicles orbicular. 167. Alyssum, 120. 



Silicles ovate or oblong. 168. Draba, 121. 



Silicles either not compressed or compressed 

 contrary to the partition. 



