HAZEN: TRIMORPHISM AND INSECT VISITORS OF PONTEDERIA 469 
globule. This same change of the colorless idioblasts to blue has 
also been observed in fading flowers of P. montevideensis treated 
in a similar fashion, while the pink idioblasts remain unchanged 
in appearance. 
It would be a matter of much interest to be able to determine 
the function of these three sorts of hairs. Kerner and Stahl* 
would doubtless regard the perianth hairs as a protection against 
undesirable creeping insect visitors and snails. If this were their 
function, here it might have been more easily secured if the hairs 
had been developed on the large spathe-like bract just below the 
flowers. Goebelerf regards the glandular and tannin-bearing 
hairs abundantly present on young fern shoots as serving in a 
much higher degree as a protection against desiccation, by dimin- 
ishing transpiration, and by absorbing.and storing water or con- 
ducting it back to young tissues. Pontederia shows a strong 
tendency to dry up on the slightest provocation, and the hoary 
glandular covering so conspicuous all over the young buds and 
even over the stem down to the point of insertion of the bract, 
may well furnish a protection against excessive transpiration. 
Along this line, it is also suggestive, that the hairs on the stamens 
and styles are chiefly found on the parts exposed when the flower 
is opened, and that they are almost entirely absent from the short- 
styled pistil, which is so completely enveloped by the perianth 
tube as to need no other protection. . The longer stamen hairs do 
also, in some cases at least, catch the pollen from the anthers and 
hold it in the most advantageous position in relation to insect 
visitors, but it can hardly be supposed that so specialized a form 
was evolved for such a purpose. Knuth{ found that the flowers 
of Sicyos angulata L. acted upon a photographic plate much more 
strongly than their inconspicuous greenish-white color would lead 
one to expect, and suggested that this may be due to the numerous 
glands covering the flowers which possibly “асі as so many mirrors 
or lenses receiving and reflecting light, so that their glitter strongly 
iiec E. Pflanzen und Schnecken. Jen. Zeitsch. Naturwiss. 22: 557-684. 
s Goebeler, E. Die Schutzvorrichtungen am Stammscheitel der Farne. Flora 
69: 483-497. 1886. See also Gardiner, E., & Ito, T. On the structure of the 
mucilage-secreting cells of Blechnum and днае Ann. Bot. 1: 30. 1887. 
Knuth, P. Handbook of Flower a I: 87. 1906. 
