462 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
tion of Darwin's book, Mr. Leggett reported* that he found on 
examination of growing plants that Pontederia cordata “15 as truly 
trimorphic as Lythrum Salicaria, or even more so." His brief 
account appears to have received little notice in this country, for 
only one of our manuals mentions the trimorphism, and to answer 
some of the questions raised by Mr. Leggett as to the insect 
visitors, the relative fertility of the three forms, and the function 
of the peculiar glands which beset the flowers, was the purpose of 
the investigations now to be reported. 
Early in July, 1916, while searching for another plant seen 
during a previous season at Arcola, a trol ey station about midway 
between Hackensack and Paterson in Bergen County, New Jersey, 
I was attracted by the opportunity to secure a good photograph 
in natural surroundings of our pickerel-weed—a plant which does 
not seem to grow extensively in the immediate vicinity of New 
York. Here at Arcola it was abundant in two long ditches in a 
pasture, and presently the attempt to obtain a photographic 
record of its numerous insect visitors became a fascinating pursuit. 
I made many visits to the station during the remainder of July, 
August, and September, always laden with cameras and butter- 
fly-net and killing-bottle. F lowering spikes were generally 
brought back from the field for laboratory study, and though all 
the flowers opening on any one morning begin to fade often by 
mid-afternoon if the day is sunny, later if it is cloudy or humid, 
nevertheless when brought to the greenhouse, the spikes would be 
furnished with freshly opened flowers for several successive morn- 
ings. The flowering proceeds in general from below upwards, but 
as not more than one of the three or four flowers of a single spikelet 
or sessile cluster of buds is open at one time, the main portion of 
the spike may be well clothed with new flowers for some days. 
In this way the biological advantages of conspicuousness of the 
whole inflorescence and economy in condensation of the axis and 
spacing of the open flowers are maintained at the maximum degree 
of efficiency. 
As Mr. Leggett discovered, the species consists of three kinds 
of plants, each kind bearing a flower of somewhat different form. 
At one time I thought the different plants might be recognized by 
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