THE STAMINATE FLOWER OF ELODEA. 
BY ROBERT B. WYLIE. 
Vegetatively Elodea is perhaps the best known of the submersed 
seed plants, as it is so commonly employed in the laboratory for experi- 
ment and study. The 'flowers, however, have received proportionately 
less study since they are small and inconspicuous and seldom appear in 
the usual laboratory aquaria. The purpose of this paper is to call at- 
tention to an unusual form of staminate flower recently noted. 
While the flowers in this genus are usually functionally dioecious they 
are of special interest in that the suppressed parts are nearly always 
present in rudimentary form and the separation of the sporangia is 
doubtless correlated with their adjustment to the aquatic environment. 
They are unquestionably quite recently derived from perfect flowers. 
They present an ingenious solution of the problem of pollination since 
the minuteness of the flowers enables them to use the surface film of water 
to good advantage.^ 
The pistillate flowers of Elodea, as is well known, are regularly 
elongated, and reach the surface, if at all, through the lengthening oL 
that part of the flower between the ovary and floral parts. This ‘‘floral- 
tube” of the epigynous flower may attain to a length of 10-15 centimetres 
though having a diameter of only a fraction of a millimetre. The stami- 
nate flower, on the other hand, employes an entirely different method 
of reaching the surface of the water. These ordinarily do not elongate, 
or but slightly, and remain until fufly developed within the sessile globose 
spathe. At maturity the stem or pedicil weakens, the flower escapes 
from the sheath, and rises to the surface of the water, there scattering 
the pollen. My observations have led me to think that the detachment 
and rapid rise of these flowers and their bursting open as well is greatly 
facilitated by the bubbles of gas that form at their tips buoying them 
up like balloons tugging at their anchorages. 
During the summer of 1909, in connection with work at the Iowa 
Lakeside Laboratory, the writer noted an unusual form of staminate 
^Wylie, R. B. The Morphology of Elodea Canadensis. Bot. Gazette 37:1-22, 
1904. 
