74 



FRUITS 



153. — Follicle of milk- 

 weed. 



a single carpel, which may be regarded as a modified leaf. 

 Examine one of these pods and you will 

 find that it splits down one side, which 

 corresponds to the edges of the leaf 

 brought together and turned inwards to 

 form a placenta for the attachment of 

 the seed. This line of 

 union is called a suture, 

 from a Latin word 

 meaning a seam. 



95. The Carpel a 

 Transformed Leaf. — 



The leaflike nature of 

 the carpel is very evi- 

 dent in such fruits as 



the follicles of the Japan varnish tree 



{Sterculia platanifolia), where even the 



veining is quite distinct, and the whole 



carpel so leaflike in appearance that "='« °f J^P^" vamish 



tree \ s s siiturss 



there is no mistaking its nature. Indeed, 



after the wonderful transformations we have already found 

 leaves undergoing, their development into 

 the hardest and thickest of carpels need 

 not surprise us. 



96. The Legume. — Get a pod of any 

 kind of bean or pea, and observe that it 

 differs from the follicle in having two 

 sutures or lines of dehiscence. One of 

 these, which runs along the back of the 

 carpel and corresponds to the midrib of 

 the leaf, is called the outer, or dorsal, su- 

 ture ; the other, corresponding to the 

 Legume of united edges of the carpellary leaf, is the 



V, ventral . -^ 



rf, dorsal inner, or ventral, suture, so called because 



154. — Leaflike folli- 



bean: 

 suture : 

 suture. 



it always turns inwards, that is, towards 

 the center or axis of the flower. 



