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 ; w T hile 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 Houstonia ccerulea , 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 
