134 



FERTILIZATION AND POLLINATION 



21) Iiiibni rem i 

 iii()ii(F( Kms pi lilt 

 \vi t li stciininate 

 rtoweis borne in 

 the tassel and 

 pistillate tlowers 

 borne in the ear. 



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 cal^'x 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 flnd 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 

 Cleistogamous flowers usually appear 

 They seem to insure 



pea -like flowers 



after the showy flowers have passed 



a crop of seed by a 



method which expend 



little of the plant' 



energy. See Fig. 216 



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 la pollen discharged? What is meant 



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

 cleistogamous tiower at o. 



