218 APPLIED BIOLOGY 



called " seeds/' but the outer hull is from the wall of ovary 

 and corresponds to a bean pod, while the seed with its own 

 coat is inside. 



(L) Examine a buckwheat or sunflower fruit ("seed"). 



In the akene fruits of the composites (e.g., dandelion), the 

 calyx usually adheres to the outer wall of the ovary, while 

 the upper edge of the calyx appears on the ripened fruit as a 

 tuft of hairs which aid in the dispersal of the seeds. 



Grains. In the unopened grains or fruits of the rice, oats, 

 barley, etc., the outer hull is formed from the wall of the ovary. 

 This hull is entirely filled with the seed, and the seed-coat ad- 

 heres to the ovary-wall. 



Nuts. The nuts of the oak (acorn), beech, and chestnut 

 are true fruits, very much like the akenes, except that usually 

 the dried ovary- wall is very hard. The kernel inside is the 

 seed and has its own seed-coat. 



In the true edible chestnuts, beech-nuts, and hazel-nuts, 

 two or three nuts are within a bur (involucre) ; but each nut 

 has developed from one ovary (i.e., is a true fruit). In the 

 case of the oak fruit (acorn), the acorn-cup surrounds the one 

 true fruit (from one ovary) . The burs of chestnut and beech, 

 acorn cups, and hazel hulls are formed from bracts of the in- 

 volucre, which grow up and surround the ovary. 



The outer hull of walnuts, hickory nuts, and husks of co- 

 coanut develop from the outer wall of the ovary, while the 

 inner wall forms the shell (see under stone-fruits). The 

 Brazil nut is a seed with a very hard seed-coat, and a number 

 of such seeds are inclosed in a hard-walled shell which comes 

 from the wall of the ovary. This is also the case in the horse- 

 chestnut and buckeye, where a fruit has two seeds (so-called 

 " nuts ") developed in a single ovary, and the hull is formed 

 from the outer wall of the ovary. 



Many-seeded Dry Fruits. The bean pod opens along both 

 edges or sutures. Other pod-like fruits with many seeds open 

 along one edge only, and are called follicles. The fruits of 



