132 WEEDS OF THE FARM AND GARDEN 



when the ovule is curved on itself, as in chickweed; am- 

 phitropous, when the body of the ovule stands trans- 

 versely to the stalk ; anatropous, when the ovule is in- 

 verted and the opening close to the hilum ; the ridge 

 extending along the ovule is called the raphe. 



The fruit is the matured pistil, including whatever- 

 parts are attached to it. The seed vessel is called the 

 pericarp. The principal kinds of fruit are: The simple 

 fruit, resulting from the ripening of a single pistil, an ex- 

 ample being the bean pod; the 

 simple fruits are divided into 

 the dry fruits, stone fruits and 

 berries; an aggregate fruit 

 formed when a cluster of car- 

 pels of a single flower are crowd- 

 ed in a mass, as in the rasp- 

 berry ; and multiple fruit formed 

 by the union of a cluster of 



_,. ' , , pistils of several flowers, as in 



Fig. 81. Two cotyledons b 

 of bean; r, radicle; p, plum- the mulberry. 

 ule. An exalbuminous seed Fruits may also be divided 



into dehiscent and indehiscent. 

 The dehiscent fruits are repre- 

 sented by the legume, a true pod which comes from a simple 

 pistil with dehiscence on both sides, as in the pea and bean ;the 

 follicle, a pod formed from a simple pistil and dehiscent by the 

 ventral suture, as in the larkspur ; capsule, a dehiscent fruit 

 of a compound pistil. Modifications are a Pyxis? which 

 opens by a circular line, as in the purslane and plantain ; 

 silique, like the pod of the mustard, which has two parietal 

 placentae. The indehiscent fruits are nearly always one- 

 seeded, the more important kinds being the achene (ache- 

 nium), a one-seeded, seedlike fruit, like that of the sun- 

 flower, buttercup and smartweed ; samara, a keylike fruit 

 provided with a wing, as in the maple and ash ; the utri- 

 cle, somewhat like an achene, but with a loose membrane, 



