TROPICAL WATER PLANT. 
37 
A TROPICAL WATER PLANT.* 
The Fluviales constitute one of the most interesting and fruit¬ 
ful groups for study in the whole plant kingdom not only from 
a morphological, but from an ecological standpoint. A Swedish 
botanist, Dr. Svedelius, has added another interesting contribu¬ 
tion to our knowledge of the group. His observations were made 
during 1902-03 while on the island of Ceylon where Enalus and 
several others of the tape-grass family are found. Enalus acor¬ 
oides, like the familiar fresh-water eel-grass (Vallisneria ), is one 
of those hydrophilous plants which effect pollination by the break¬ 
ing off of the staminate flowers under water, by their rising to the 
surface and by their floating to the pistillate flowers. 
Svedelius finds that in both stem and root the vascular system 
is poorly developed. The vessels are few and not lignified. The 
cortex is strongly developed and the internal layers are filled with 
huge starch grains. Many tannin cells occur throughout the 
vegetative tissue, also in the pedicels of the staminate flowers. 
They are also found in great abundance in the perianth of the 
pistillate and to a less degree in the perianth of the staminate 
flowers. 
The single pistillate flower, as well as the large cluster of 
staminate flowers, is surrounded by a double spathe which in the 
former has much to do with pollination. The bud formed by 
these spathe leaves is about five cm. long by three cm. in diameter 
in the case of the staminated inflorescence, while in the case of 
the pistillate flower the diameter is but one cm. A large number 
of staminate flowers are attached by long slender pedicels to a 
common axis. At the period of flowering the spathe leaves open 
a short distance at the top, their edges rolling back slightly, the 
pedicel ruptures, allowing the globular bud, fil.ed with gas, to 
ascend to the surface. Upon reaching the surface the six-parted 
perianth opens explosively, owing to the release of water pressure, 
leaving the three almost sessile anthers above the level of the 
* On the Life-history of Enalus ac or aides (a contribution to the ecology 
of the hydrophilous plants), by Nils Svedelius. Ann. R. Bot. Gard. Pera- 
diniya 2: 267-297. Aug. 1904. 
