134 



FERTILIZATION AND POLLINATION 



with these degenerate flowers. Only a few 

 plants bear cleistogamous flowers. Hog- 

 peanut, common blue violet, fringed win- 

 tergreen, and dalibarda are the best 

 subjects in the northern states. Fig. 215 

 shows a cleistogamous flower of the hog- 

 peanut at a. Above the true roots, slen- 

 der rhizomes bear these flowers, which are 

 provided with a calyx and a curving 

 corolla which does not open. Inside are 

 the stamens and pistils. The pupil must 

 not confound the nodules on the roots of 

 hog -peanut with the cleistogamous flow- 

 ers : these nodules are concerned in the 

 appropriation of food. Late in summer 

 the cleistogamous flowers may be found 

 just underneath the mould. They never 

 rise above ground. The following sum- 

 mer one may find a seedling plant with 

 the remains of the old cleistogamous 

 flower still adhering to the root. The 

 hog -peanut is a common low twiner in 

 woods. It also bears racemes of small 

 pea -like flowers. Cleistogamous flowers usually appear- 

 after the showy flowers have passed. They seem to insure 

 a crop of seed by a 

 method which expends 

 little of the plant's 

 energy. See Fig. 216. 



214. Indian corn, a 

 mono3cious plant, 

 with staminate 

 flowers borne in 

 the tassel and 

 pistillate flowers 

 borne in the ear. 



REVIEW. What is fer- 

 tilization ? Pollination ? 

 Define cross- and self-pol- 

 lination. Which gives the 

 better results, and how? What is meant by the selective power of the 

 pistil? Describe a receptive pistil. Exhibit one. By what agents is 

 cross-pollination secured? How is pollen discharged? What is meant 



215. Hog-peanut, showing a leaf, and a 

 cleistogamous flower at a. 



