200 



BOTANY: PRINCIPLES AND PROBLEMS 



bean), which arises from a simple or single-chambered one. 

 Others arc dry but do not split open. Such are the achene (as 

 in the buttercup), the commonest type of single-seeded fruit; 

 the nut (as in the hickory), in which the pericarp becomes hard 

 and woody, and the grain (as in the corn), the characteristic fruit 

 of the grass family, in which seed coats and pericarp are firmly 

 fused. These single-seeded fruits are often mistaken for seeds. 

 Many fruits become fleshy, at least in part. In the bernj (as 



Fig. 114. — Seed dihpersal by the wind. A, npe fruit of the milkweed, Ascle- 

 pias. Each seed is provided with a tuft of feathery hairs, which aid in the dispersal 

 of the seeds by the wind. B, fruits of the cotton-grass, Eriophorum. Each 

 tuft in the picture is composed of a group of single-seeded fruits, attached to each 

 of which is a cluster of long, cottony hairs. 



in the blueberry), the entire fruit is so except the seeds, which 

 have thick coats. In the stone fruit or drwpe (as in the cherry), 

 the outer part of the pericarp is fleshy but the inner portion, 

 enclosing the seed, is a hard and woody "stone." In the pome, 

 represented by such fruits as the apple and pear, it is the recep- 

 tacle, grown around and enclosing the fruit, which becomes 

 fleshy, the pericarp being represented here only by the tough 

 membranes of the core. 



