HAZEN: TRIMORPHISM AND INSECT VISITORS OF PONTEDERIA 481 
. were watched from a boat, and no butterflies, but numerous bees 
were seen visiting the plants, though one of the photographs taken 
there shows clearly a humming-bird moth with extended proboscis 
poised before a flower. Knuth would doubtless place this plant 
having a perianth tube of seven or eight millimeters in length 
among his groups of bee- or humble-bee-flowers, but the record 
at Arcola shows clearly that such a classification cannot be rigidly 
adhered to in this case, for there certainly the Lepidoptera sur- 
passed the bees as visitors of this plant both in number of species 
and individuals. This I think was the case throughout the whole 
of July and August, though constant pursuit with the camera and 
net prevented making an exact record of the number of visits of 
any particular species. 
Unquestionably the least skipper, Azcyloxypha, was the most 
frequent visitor, two or three individuals often being present on 
one spike, and often one of them flitted to several flowers on the 
same spike in succession; this was always an attractive little 
butterfly as the golden-brown scales on the lower surface of the 
folded wings caught and reflected the sun. These smaller butter- 
flies, using the alighting platform furnished by the spreading 
lower lip of the flower, get the under side of their thorax or abdomen 
well dusted with pollen from the longest stamens (PLATE 15) and 
then carrying it to a long-styled flower rub off some of it on the 
protruding stigma; at the same visit they may dust the head with 
pollen from the mid-length stamens, or thrusting.the proboscis 
into the tube on the upper side of the flower where there is a 
wider space between the perianth and the pistil than on the lower 
side, on withdrawing it after sucking the nectar, they drag it 
through the row of three inverted anthers of the shortest stamens 
(FIG. 1) to carry the pollen away to other flowers with appropriate 
length of style. Larger butterflies, like the silver-spotted skipper, 
often stand out farther from the flowers so that only the legs and 
proboscis tip become dusted with pollen, though one photograph 
of the black swallow-tail shows it grasping the spike with the 
abdomen tightly pressed against the flowers. The persistent 
visits of these large butterflies furnish the strongest reason for 
doubting the rigid applicability of Knuth's classification in the 
case of this plant. Standing at the south end of a ditch filled, 
