132 PLANT PHYSIOLOGY AND ECOLOGY 



ovary is soft. In the drupe or stone fruit, apricot, cherry, peach, 

 etc., the outer part of the wall becomes fleshy, while the inner 

 hardens into stony tissue. On the other hand, the pepo has 

 developed a hard rind upon the outside, while the inside is pulpy. 

 The pome of the apple and pear resembles a berry, but the flesh is 

 the modified calyx, the pistil being represented by the papery 

 core. 



154. Dry fruits are leaf -like, papery, membranous, or hard in 

 texture. Indehiscent dry fruits, i.e., those that do not split open at 

 maturity, are the achene, the nut, the samara, and the grain. The 

 achene is a small seed-like fruit, such as is found in the buttercup, 

 strawberry, sunflower, thistle, dandelion, etc . The nut is a fruit which 

 possesses a hard stony wall, such as is found in the acorn, hickory, 

 and walnut. The samara is an indehiscent fruit provided with a 

 wing, e.g., the ash, elm, and maple. A grain is an achene in which 

 the wall of the ovary is completely fused with the seed, as in corn, 

 wheat, and other grasses. Dehiscent dry fruits, or those that split 

 open at maturity, comprise the utricle and the pod, the latter 

 being subdivided into the follicle, legume, loment, capsule, silique, 

 silicle, and pyxis. A utricle is an achene with a loose, dehiscent 

 pericarp, such as is seen in the amaranth and goosefoot. All 

 other fruits which split open at maturity are grouped under the 

 general term pod. The follicle is a simple pistil which splits 

 along the inner suture, e.g., columbine, larkspur, and milkweed. 

 The legume is a follicle which opens along both sutures, thus 

 splitting into valves, as in the bean, pea, vetch, etc. The legume 

 is called a loment when divided into one-seeded joints that separate 

 at maturity. The capsule is the pod of a compound pistil. The 

 pod of the mustard family, or silique, is two-celled in consequence 

 of a false partition which stretches between the valves. The 

 silicle is a short, broad silique, such as that of the shepherd 's- 

 purse; while the pyxis opens circularly by means of a lid, e.g., 

 the plantain and the purslane. 



155. Movements of fruits. The way in which fruits and seeds 

 are scattered about is chiefly determined by the nature of the 

 fruit, as will be shown in detail under Migration. Certain move- 

 ments are also concerned in this to some degree. These so-called 

 carpotropic movements result from the bending of peduncle 

 or pedicel, by which the position of the fruit is changed, or from 

 the growth of the peduncle, by means of which the flower cluster 



