AND CROSS-FERTILIZE THEIR FLOWERS. 



37 



has bent so far forwards as to point downwards, and the stigma is not yet ready for 

 pollen, its two branches being united. So a butterfly, in the act of drawing nectar 

 from this flower, will get the under side of its body dusted with pollen, but will 

 not come near the reflexed and still immature style. But in a flower a day older, 

 the stamens are found to be coiled up (the opposite way from what they were in 

 the bud) and turned down out of the way, bringing the anthers nearly where the 

 stigma was the day before ; while the style has come up to where the stamens 

 were the day before, and its stigma with branches outspread is now ready for 

 pollen, — is just in position and condition for being dusted with the pollen which 

 the butterfly has received from the anthers of an earlier blossom. 



75. Campanulas and Sabbatias also mature their anthers and shed their pollen 

 long before the stigmas open so as to receive any ; they, too, are fertilized by in- 

 sects carrying pollen from an earlier to a later flower. To understand how it is 

 done in each particular case the flowers themselves should be studied in the field 

 and garden. 



76. Dimorphous Flowers, that is, flowers of two kinds as to length or position of 

 stamens and pistil, but both sorts perfect, remain to be considered. In these the 

 difference is only in the stamens and pistil, usually merely in their relative length, 

 and very likely to be noticed only by the attentive observer. A good case of this 

 may readily be seen 



77. In Houstonia. The com- 

 monest species, the little blue- 

 eyed Hmistonia casrulea, looks 

 up to us from every low mead- 

 ow in spring as soon as the turf 

 gets dry enough to set foot 

 upon. In different patches of 

 it, some flowers will show the 

 tips of the four stamens slight- 

 ly projecting ; as many others 

 will show the two stigmas 

 only. The two kinds are al- 

 ways in different patches ; all 

 that come from the same seed 

 being alike. The sort that shows the tips of the anthers (as in Fig. 33, and with 



Figs. 83, : 

 and 36. 

 open. 



5. The two sorts of flower of Houstonia. csemlea. 84 

 Same more enlarged, with corolla divided and laid 



