262 LSSSOIfS WITH PLANTS 



rable portions are known as valves. The legume is, therefore, 

 2-valved. 



307. The pupil has seen the flower 



and pistil of the mustard (Figs. 133, 



134) . Inasmuch as this pod is 2- 



carpelled, with a partition extending 



from side to side, we should look for 



a different type of dehiscence from that 



Pig. 249. occurriug vo. the simple follicle and the 



(Sef fS'.) legume. The mature pod in Fig. 135 



shows the method of dehiscence, the 



valves breaking away at the base and leaving 



the placentae and partition. 



307a. This mustard fruit is charaoteristio of the family, — the 

 cabbages, turnips, radishes, wallflowers, stocks, alyssum, and the 

 like. When the pod is prominently longer than broad, as in the 

 mustard, it is known as a silique, but when broader than long, as 

 in the shepherd's purse, it is called a silicle. The mustard fruit 

 is 2-loculed by a false partition which stretches across it, — that 

 is, by a partition which is not a part of the structure of the 

 young ovary; but the pod is 2-oarpelled, as may be seen by the 

 two marginal plaoentse (which are joined by the partition). While 

 the mustard fruit is compound, it might be mistaken, therefore, 

 for a simple pod. 



308. It is not necessary that all pods open 

 longitudinally. There are many kinds of de- 

 hiscence, and some of them follow no definite 

 method. An occasional type is such as one finds 

 in the purslane (or "pussley"), door-yard plantain, 

 henbane, and one of the pigweeds or red -root, in 



