80 



PLANT RELATIONS. 



FIG. 73. A flower of the tobacco plant : a, a complete flower, showing the calyx with 

 its sepals blended below, the fnnnelforin corolla made up of united petals, and the 

 stamens just showing at the mouth of the corolla tube ; 6, acorolla tube split open 

 and showing the five stamens attached to it near the base ; c, a pistil made up of 

 two blended carpels, the bulbous base (containing the ovules) being the ovary, the 

 long stalk-like portion the style, and the knob at the top the stigma. After 

 STRASBXJRGER. 



last set of floral leaves (carpels) appear, the growth of the 

 stem in length is checked and the cluster of floral leaves 



b c d e 



FIG. 74. A group of flower forms : a, a flower of harebell, showing a bell-shaped 

 corolla composed of five petals ; 6, a flower of phlox, showing a tubular corolla 

 with its five petals distinct above and sharply spreading ; c, a flower of dead-nettle, 

 showing an irregular corolla with its five petals forming two lips above the funnel- 

 form base ; d, a flower of toad-flax, showing a two-iipped corolla, and also a spur 

 formed by the base of the corolla ; , a flower of the snapdragon, showing the two 

 lips of the corolla closed. After GRAY. 



