140 



FERTILIZATION AND POLLINATION 



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

 cleistogamous flower at a. 



showy flowers that may be insect-pollinated, and in addi- 

 tion is provided with these specialized flowers. Only a few 

 plants bear cleistogamous flowers. Hog-peanut, common blue 

 violet, fringed winter- 

 green, and dalibarda 

 are the best subjects 

 in the northern states. 

 Fig. 235 shows a cleis- 

 togamous flower of the 

 hog-peanut at a. Above 

 the true roots, slender 

 rhizomes bear these flowers, which are provided with a 

 calyx and a curving corolla that does not open. Inside are 



the stamens and pistils. The 



/\ s pupil must not confound 



_/**W~ .***/ * the nodules on the roots of 



the hog-peanut with the 

 cleistogamous flowers: these 

 nodules are concerned in the 

 appropriation of food. Late 

 in summer the cleistogamous 

 flowers may be found just 

 underneath the mold. They 

 never rise above the ground. 

 The following summer 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 



a 



236. Common blue violet. The familiar 

 flowers are shown, natural size. The 

 corolla is spurred. Later in the season, 

 cleistogamous flowers are often borne 

 on the surface of the ground. A small 

 one is shown at a. A nearly mature 

 pod is shown at b. Both a and b are 

 one-third natural size. 



