206 



GROWTH AND WORK OF PLANTS 



325. In general, fruits are dry or fleshy. Dry fruits may 

 be grouped under two heads. Those which open at maturity 

 and scatter the seed are dehiscent. Those which do not open are 

 indehiscent. 



II. INDEHISCENT FRUITS. 



326. The akene. The thin, dry wall of the ovary encloses 

 the single seed. It usually does not open and free the seed within. 

 Such a fruit is an akene. An akene is a small, dry, one-seeded, 

 indehiscent fruit. All of the crowded but separate pistils in the 



buttercup flower when ripe make a head 

 of akenes, which form the fruit of the 

 buttercup (fig. 156). Other examples 

 ot akenes are found in other members 

 of the buttercup family, also in the 

 composites, etc. The sunflower seed is 

 a good example of an akene. It should 

 be borne in mind that the sunflower 

 "seed" (and "seed" of other composite 

 flowers) is a fruit containing the seed. 



327. The samara. The samara is 

 a dry fruit, with a thin membranous 

 expansion extending more or less around 

 the edge, somewhat resembling wings, 

 which serve to float the seed and aid 

 in distribution by the wind. The 

 "winged" fruits of the maple, box 

 elder (fig. 158), elm, etc., are examples. 

 They are sometimes called "key" fruits. 



328. The grain (or caryopsis) is a dry fruit in which the seed 

 is united with the pericarp (wall of the ovary), as 'in the wheat, 

 corn, and other grasses. It is perfectly proper to say "seed 

 wheat," "seed corn," "grass seed," etc., if it is understood that 

 these grains are fruits including the seed. It would be absurd to 

 insist that in all such cases one must avoid the use of the term 

 seed when speaking of the grains and of akenes, and use instead 



Fi 3 . 158. 



A winged fruit, a samara, fruit 

 of the box elder. 



