30 ELEMEKTS OP STRUCTURAL BOTANY. 



one of the petals is large, broad, and open, whilst two 

 smaller ones, in the front of the flower, are united into a 

 kind' of hood. IVe 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 butter- 

 fly, it is said to \e papilionaceous. 



40. Eemove now the calyx-teeth and the petals, being 

 very careful not to injure the stamens and the pistil, en- 

 veloped 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 occiiS in this way, in two distinct groups, they 

 Are said to be diadelphous ; if in three groups, they would 

 be triaddphous ; if in several groups, polyadelphous. In 

 the Mallow, you will remember, 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 of 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 thd* Buttercup and the other flowers examined. 

 In the present instance they are inserted upon the lower 

 part of the calyx, and so they are described as perigynous, 

 a term meaning " around the pistil." 



41. But the pistil (Egs. 38, 39) is not attached to the 

 calyx. It is free, or sitperior. If you cut the ovary 

 across, you will observe there is but one cell, and if you 

 examine the gtigma, you will find that it shows no sign 

 of division. You may therefore be certain that the pistil 

 is a single carpeL 



