HAZEN: TRIMORPHISM AND INSECT VISITORS OF PONTEDERIA 479 
the axis of the spike in a nearly horizontal, though slightly as- 
cending position, indicates that automatic self-pollination is 
regularly precluded (кіс. 11 and PL. 14). In the long-styled flower 
the stigma stands out stiffly too far to be reached by pollen from 
its own anthers, and these are so nearly included in the perianth- 
tube that pollen from them would be very unlikely even to fall on 
stigmas lower down on the same spike; in the short-styled form 
it would be impossible for the pollen to drop down the long, narrow 
tube to the low stigma. Only in the mid-styled form does it appear 
that pollen from the long-exserted anthers might possibly fall on 
the stigma of a lower flower, and here again in all ordinary cases 
the erect upper lip of the perianth would protect the lower stigma, 
which furthermore hardly projects from its tube far enough to 
catch pollen from above. 
Among the insect visitors of the pickerel-weed ten species of 
Lepidoptera, distributed among five families, and showing nearly 
all possible range in size were collected during several excursions 
in July and August, 1916, and all of these but two or three were 
photographed as they sipped nectar from the flowers, several 
species many times. The list includes the least skipper, Ancy- 
loxypha numitor Fabr.; the yellow-spotted skipper, Polites peckius 
Kirby; the silver-spotted skipper, Epargyreus tityrus Fabr.; the 
variegated fritillary, Euptoieta claudia Cramer; the clouded sul- 
phur, Colias philodice Godart; the white cabbage butterfly, 
Pieris rapae L.; the viceroy, Basilarchia archippus Cramer; the 
tiger swallow-tail, Papilio turnus L.; the black swallowtail, 
Papilio polyxenes Fabr.; and the humming-bird moth, Hemaris 
thysbe Fabr. It is strange that the monarch butterfly, Anosia 
plexippus L., which was frequently seen on neighboring plants of 
Joe-Pye weed, never visited the Pontederia,and the so-called mimic, 
the viceroy, made only one fleeting visit; they evidently prefer 
the large flat-topped flower clusters of Eupatorium and milk-weed, 
or the nectar found there; or is it possible that blue flowers do not 
attract them? Another curious case was that of the pearl crescent 
butterfly, Phycioides tharos Kirby, which was the commonest 
visitor of the vervain, Verbena hastata L.; growing close to the 
pickerel-weed ditch, but never came to the Pontederia, though 
the latter possesses much the same blue color and has a similar 
