316 WALDRON— THE PEANUT 



lengthens and sinks into the soil carrying the head with it. The 

 seeds do ripen above ground, however, and will germinate. 



Differing from both of these, Arachis and the other two genera 

 mentioned above have a nearly uniform type of flower, the ovary of 

 which is pushed into the ground by a growth at its base. The elong- 

 ating fruit stalk is called a "gynophore." 



Anatomy of the Young Gynophore. Observations by the writer 

 correspond to most of those of Pettit, whose article is chiefly concerned 

 with the structure and development of this organ. Sections made 

 longitudinally through young flower buds reveal a nearly sessile 

 ovary usually containing two parietal ovules each, on a short funi- 

 culus (Plate LXXIX, Fig. 8). There are ii to 13 bundles which ex- 

 tend through the base of the ovary to the tip, branching more or less- 

 in their course. Along the inner edge of each bundle are tannin 

 pockets. After the egg is formed and fertilized, the reduced ovarian 

 axis begins to elongate to form the gynophore. The ovary and em- 

 bryo sac remain unchanged in this condition until the gynophore is 

 mature. This will be further discussed under physiology. The 

 later cytological study of the embryo was not attempted. 



The meristematic tissue which gives rise to this growth is mostly 

 situated just below, and around the base of the ovary. That below 

 the ovary forms the pith, while that around the base forms the bundle 

 tissue and outer cortex. A few dividing cells forming the latter 

 were found well up around the ovarian cavity. The epidermis of 

 the tip becomes sharp pointed and highly lignified in its outer walls. 

 In Plate LXXIX, Fig. 9, is seen the area at one side of the tip where 

 the style was formerly attached. This style is terminal in very young 

 buds, but the later lateral position of the scar is prearranged for 

 by a special development of a few large lignified epidermal cells at 

 one side of its base. (Plate LXXIX, Fig. 8). These grow forward 

 a little, and form the sharp point of the ovary. 



Anatomy of the Mature Gynophore. While the structure of this 

 fruit stalk corresponds to that of the stem of any herbaceous dicoty- 

 ledon, its manner of development resembles that of ordinary roots. 

 There are no lateral appendages, and so no nodes and internodes. 

 There are two distinct divisions of this organ (i) the epigeal part, 

 with smooth, red pigmented surface bearing a few three celled hairs 

 similar to those on other parts of the plant; (2) the hypogeal white 

 part, whose surface produces single-celled absorptive hairs. (Plate 

 LXXIX, Fig. 7.) The surface of the aerial portion is covered with 



