103
ON SOME WATER PLANTS.
Being a Presidential Address delivered to the Club at the Annual Meeting
on 29th March, 1919.
By GULIELMA LISTER, F.L.S.
(With 7 Illustrations.)
THOSE of us who are privileged to live on the borders of
Epping Forest may find in its ponds and little pools
unfailing interest and pleasure. Whether we visit them in winter
when the delicate tracery of the hornbeams and birches is
mirrored on the still surface of the water and the winter moths
flutter down to meet their own reflections, or in summer When
the blue dragon flies chase each other about the Wealth of her-
bage that has grown up, whether our interest is in animal or
plant life, each pond will be found to have its own character
and charm. I propose this afternoon to talk about a few of the
water plants that grow in our forest pools and in the Roding,
and especially of those flowering plants that develop different
forms of leaves, according to the conditions under which they
live.
Plants growing in water may have either aerial leaves,
floating leaves, or submerged leaves; some plants will have
all three kinds of leaves.
Such an one is the Great Water Plantain (Alisma Plantago),
whose erect oval leaves and large much branched panicles of
pale mauve honied flowers are conspicuous in late summer in
most of our ponds. The seedlings produced from such plants
have a very different appearance from their parents. If we
follow the history of the light flat fruits that fall, float, and
drift on the surface of the water, we find that they eventually
sink to the mud at the bottom, where they pass the winter. In
spring the seeds germinate and put forth a tuft of narrow trans-
lucent leaves, two to six inches long, which might almost be
mistaken for those of a grass. These 'ribbon' leaves are well
adapted for a submerged life. Being always bathed in water
they have no stout external cuticle, such as leaves growing
in the air require to protect them from drying winds; they
are supported by the water and so do not need tissues forming
either the stiff armour or strong internal props such as are