THE FLOWER 



24^ 



D. Protective Adaptation 



Experiment 83. Are the floral envelopes op any use ? — Care- 

 fully remove the calyx and corolla from a young flower bud on a growing 

 plant and see what will happen. Remove them from a flower just unfold- 

 ing. Mark each by tying a colored thread lightly around the petiole and 

 see if it sets as many seeds, or as good ones, as the unmutilated flowers on 

 the same plant. 



Experiment 84. Is the position of a flower on the stem of any 

 importance ? — Invert a blossom of pea or sage, and see what parts would 

 come in contact with the body of a visiting insect. How would its chances 

 for pollination be affected? Try to make a flower grow in an inverted 

 position by tying or weighting it down, and watch the effect on seed pro- 

 duction. 



Experiment 85. 

 BY light ? — Place 

 window so that the 

 position of the buds. 

 to light, and watch 



Experiment 86. 

 BY GEOTROPiSM ? — Lay a potted plant of lily of the valley, larkspur. 



Is THE position OF FLOWERS ON THE STEM INFLUENCED 



a potted plant with expanding flower buds near a 

 light will reach it from one side only, and notice the 

 After a day or two reverse the position with regard 

 whether any change of position takes place. 



Is THE POSITION OF FLOWERS ON THE STEM INFLUENCED 



357 



358 



Figs. 357-359. — Flower of monkshood, showing the changes hy which it returns 

 to its original position under the influence of geotropism after the axis of inflorescence, 

 s, has been inverted: 357, inverted position; 358, change due to negative geotro- 

 pism ; 359, change due to lateral geotropism. 



gladiolus, or digitalis in a horizontal position, tie the main stem to keep 

 it from changing its direction of growth, and leave for two or three days 

 iin a place where it is lighted equally on all sides. How do the individual 

 flowers behave ? What part bends to turn them up ? Vary the experi- 



