IOWA ACADEMY OF SCIENCE 
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flower on the Elodea plants growing in the upper end of East Okoboji 
Lake. These plants flourish most luxuriantly in the waters near the 
town of Spirit Lake, and every one of the hundreds of flowers examined 
displayed the same peculiarities, seeming to indicate a distinct strain 
of this .genus in that locality. 
The flowers under discussion displayed a form' and habit markedly 
different from described types in that they elongated similarly to the 
pistillate flowers. The lower portion of the spathe early appears con- 
tracted giving it a stalked appearance, and this may be the condition 
described as ‘‘spathe peduncled’’ by Eydberg“ in his description of 
Philotria Planchonii (Gasp.) Eydb. and P. linearis Eydb, though the 
spathe is of course really sessile. The outer end of the spathe expands 
abruptly into a flattened, circular, cleft portion which loosely invests the 
body of the flower which is truly pedicillate on an axis within the spathe. 
At maturity the axis elongates pushing the flower out through the cleft in 
the spathe and upwards toward the surface of the w^ater. The stamens 
and floral parts are thus carried up on a slender stalk looking very much 
like that of the pistillate flower. But while these habits are biological 
equivalents and the parts concerned look much alike the morphology of 
the structures involved is very different. The “floral tube” of the pis- 
tillate flower represents that complex of structures found above the 
ovary in epigynous flowers, while the elongated thread in the staminate 
flower is the pedicil. 
The flower has usually a bubble of gas tugging at its apex, and in some 
instances it was noted that, the attached flower had partly opened into 
this gas chamber. Sooner or later the weakened axis usually gives way 
and if >the flower has not already reached the surface it rises and sheds 
its pollen on the surface film. The break. occurs near the base, generally 
within the spathe, and the free floating flowers, have each a long thread 
trailing behind. These become entangled and where the plants are num- 
erous the empty flowers form windrows at the margins of the open water. 
The degree of elongation in these staminate flowers is fully as great 
as in the pistillate flowers, and the lengthening of the axis is due to the 
stretching out of cells formed at an earlier stage. A measurement of 
these stalk cells at different stages showed that they increase in length 
nearly twenty-flve times, this being accompanied by a slight decrease in 
breadth. These flowers show other structural differences which may 
not be taken up at this time. 
^Rydberg, P. A. Flora of North America. 1909. 
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