HAZEN: TRIMORPHISM AND INSECT VISITORS OF PONTEDERIA 463 
differing shades of color in the flowers, as described by Fritz Müller 
for Eichhornia azurea, in which he found the short-styled flowers 
regularly of a deeper blue, and the long-styled flowers of a paler, 
more violet tint; but on another day all of the spikes were indis- 
tinguishable in this respect. By a little observation of the position 
of the anthers, however, one may easily recognize the three forms 
without having recourse to dissection of the flowers (PLATE 14). 
Fic. 1. Pontederia cordata L.; flower of the long-styled form with the perianth 
tube cut lengthwise and laid open to show the typical position and relative height of 
all the stamens ( X 5). 
In all of the three flower forms the three narrower sepal-seg- 
ments and the three ovate petal-segments are united into a tube 
about seven or eight millimeters in length, which, however, often 
has four narrow slits in its lower part between the segments on 
the anterior or lower side of the flower, so that it would seem to be 
less efficient as a nectar receptacle than many tubular flowers. 
These clefts are so inconspicuous that they do not appear in any 
of my sketches made from fresh flowers, but are evident in 
material preserved in formalin (FIG. 1) and in pressed specimens, 
from which one might suspect that they are formed in part at 
