ELEMENTS OF STRUCTURAL BOTANY. 



27 



of the latter you will re- 

 member that each petal 

 was precisely like its 

 fellows in size aud 

 shape, and we there- 

 fore spoke of the corolla 

 as rajular. In the Pea, 

 on tlie other hand, one 

 of the petals is large, 

 broad, and open, whil4 

 two smaller ones, in 



Fig. 36, 



Fig. 38 



Fig. 37. 



the front of the flower, are 

 united into a kind of hood. We shall speak of this 

 corolla, then, and all others in which the petals are 

 unlike each other in size or shape, as irregular. 



As the Pea blossom bears some resemblance to a 

 butterfly, it is said to be papilionaceous. 



3G. Remove now the calyx-teeth and the petals, 

 being very careful not to injure the stamens and the 

 pistil, enveloped by those two which form the hood. 

 Count the stamens, and notice their form (Fig. 37). 

 You will find ten, one by itself, and the other nine with 

 the lower halves of their filaments joined together, or 

 coherent. When stamens occiir in this way, in two 

 distinct groups, they are said to be diadcljilious ; if in 

 three groups, they would be triadelphous ; if in several 

 groups, pohjadelphous. In the Mallow, you will remem- 

 ber, they are united into one group, and therefore we 

 described them as monadelphous. 



You will perhaps be a little puzzled in trying to 

 determine to what part ol the flower the stamens are 

 attached. If you look closely, however, you will see 

 that the attachment, or insertion, is not quite the same 

 as in the Buttercup and the other flowers examined. 



