42 



ELEMENTS OF BOTANY. 



distribution by the wind. That of the dandeHon will serve as an illus- 

 tration. 



The utricle is an achenium with a loose, bladdery pericarp. 



^0 



Pig 83 — ^. '^tiawbeiiy, showing 

 the seeds (achenia) immersed in the 

 fleshy receptacle. 



Fig. 85.— a blackberry. 



The caryopsis has the pericarp incorporated with the seed, as in 

 wheat, rye, and Indian corn. 



A nut is a dry indehiscent fruit with a hard woody or bony shell, as 

 in the acorn, chestnut, and cocoanut. The acorn rests in a cup-shaped in- 

 volucre, termed the CUp, or cupule ; the chestnut in a prickly bur. 



Fig. 86. — Samara of the maple. 



Fig. 87.— Samara of Fig. N8 —Follicle 

 the ailanthus. of aconite. 



A samara, or key-fruit, is either a nut or an achenium, or any other 

 dry fruit furnished with a wing to favor its distribution by the wind. Of 

 this kind are the fruits of the maple (Fig. 86), elm, tulip tree, and ailan- 

 thus (Fig. 87). 



