72 



FRUITS 



which it separates at maturity. Gather a fruiting cluster 

 of fennel, parsley, caraway, etc., and examine one of the 

 small seedHke fruits through a lens. Separate the two 

 achenes of which it is composed, and find the carpophore 

 between them. Sometimes it splits in two (Fig. 145), one 

 half going with each achene ; or they may separate from 

 it through their entire length and remain suspended from 

 the top (Fig. 144). Notice the longitudinal ribs on the 

 back of the achenes, or mericarps, as they are called. 

 Between these ridges are situated the vittce, or oil tubes to 



which the aromatic 

 flavor of these fruits 

 is due. 



90. The Samara, or 



kev fruit, is an achene 

 provided with a wing 

 to aid in its disper- 

 sion by the wind. 

 The maple, ash, elm, etc., furnish familiar examples. 



Samaras : 146, ailanthus ; 147, maple. 



91. The Grain, or caryopsis, so familiar to us in all kinds 

 of grasses, is a modification of the 

 achene in which the seed coats have 

 so completely fused with the pericarp 

 that they can no longer be distin- i48,'i49. -Grain of teoom 

 guished as separate organs. Peel corn millet: 148, front view, 

 the husk from a grain of corn that ^'^' ^"^ ^'^^" 

 has been soaked for twenty-four hours, and you will find the 



contents exposed without 

 any covering ; remove 

 the shell of an acorn or 

 a hickory nut, ajid the 

 seed will still be envel- 

 oped by its own coats. 

 Would it be any advan- 

 tage for the seed of an 

 indehiscent fruit, like a 

 grain of corn or oats, to have a special covering of its own ? 



ISO 151 153 



150-152. — Grain of wheat: 150, back view 

 151, front view ; 152, front view (magnified). 



