ON SOME WATER PLANTS. 
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A case where the application of the theory seems more diffi¬ 
cult may be seen in such a Monocotyledon as the Frogbit 
(Hydrocharis Morsus-ranae) whose rounded floating leaves are a 
conspicuous feature in summer on many of our ponds. In gen¬ 
eral appearance they look much like small Water-lily leaves, 
but the Water-lily is a Dicotyledon, and has true leaf-blades 
with normal bundles only forming the veins, while the Frog- 
bit leaves should probably be regarded not as leaf-blades, but 
as expanded leaf-stalks ; for they possess those significant in¬ 
verted bundles, which seem to show us how the leaves are to 
be interpreted. 
This brief sketch gives but an inadequate idea of the matter ; 
to understand the evidence and full bearing of the subject, 
I would refer those interested to Mrs. Arber’s lucid paper in the 
Annals of Botany. 1 
To return to the Frogbit. In the season of early spring 
the only evidence of its presence in the ponds is to be found in 
the smooth oval resting buds, which during the winter have been 
lying in mud at the bottom, and now, quickened by the warmer 
temperature, are rising to the surface, looking like little erect 
acorns. Soon the sheathing outer scales fold back and the 
first small upright leaves appear with minute kidney-shaped 
blades (as for convenience they must still be called), and the 
young rootless plants will be seen drifting about over the water 
like little rosettes. In summer the larger floating leaves and 
long hanging roots will have formed, and the frail white flowers 
will appear ; then long runners grow out, bearing at their ends 
the resting buds by which the plant is chiefly propagated. 
Water-lilies possess two kinds of leaves, namely, the familiar 
substantial flat leaves that float on the surface of the water, 
and also great wavy flaccid submerged leaves that never rise 
to the surface. On the under side of both kinds are numerous 
glands secreting mucilage, and this, by making the surface 
slimy, probably prevents too rapid diffusion of substances 
in the cell sap into the surrounding water. 2 In some reference 
books it is stated that Water-lilies also form long ribbon-leaves 
when growing in deep water, but after vain search for them 
I learn from a reliable authority that they appear to be entirely 
1 Annals of Botany, vol. xxxii , No. cxxviii., Oct., 1918 
2 Sec Willis “ Flowering Plants and Ferns" ed,. 2. p. 162 
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