The’ South Australian Naturalist . 
63 
III. AQUATIC PLANTS NOTED. 
By E. H. Ising. 
1. Ottelia ovalijolia (R.Br.) L. C. Rich. 
During two excursions this summer, two days at the end of 
January and four days April 2 to 5, the aquatic plants growing 
in the Finniss River were investigated. This is not by any means 
an exhaustive enquiry into the water plants but a preliminary 
note on several species which have been identified with certainty. 
It was not possible In the two short visits to make a thorough 
survey of these interesting plants but we hope to make further 
trips to this locality and continue the study of the aquatic as well 
as the land plants. 
This plant was fairly plentiful and was observed in flower 
on both trips. The plant is secured in the mud and sends up 
leaves springing from the base of the plant. The leaf stalk grows 
until it reaches the surface of the water and may be as much as 
two feet in length the leaf itself then spreading and floating on the 
surface. The leaves are large, being oval in shape, about 3 inches 
long and 2 inches across. The top surface is shining green and 
almost appears oily and water does not remain on it. They make 
a beautiful sight especially when the flowers are out. The flower 
stem, like the leaf, grows until the bud is produced above the water 
level, when it soon develops and opens out. No matter what the 
depth of water is, the stem accommodates itself to the situation, 
the plants growing in shallow as well as deep water. The flower 
rests exactly on the surface and it Is remarkable that after fer- 
tilisation the old flower-head will finally go below the surface 
again where It remains to mature its seeds. 
Vallisneria spiralis L. 
The Finniss River is a favorite haunt for this plant which 
was abundant In all the pools and level stretches of water. Large 
patches of the plant grew in the shallow water of the creek, while 
some plants were in three feet of water. The scour caused by 
winter rains evidently prevents the plant from getting a hold in 
the deeper water. All the leaves spring from the base of the 
plant, they are erect and always entirely submerged. When taken 
from the water they become flaccid or limp at once, the large 
and numerous air cells in the leaves and stem buoy them up when 
m the water. The leaves are from 12 to 24 inches long and even 
longer and constantly about f inch wide. They have no stalk 
being broad at the base and the apex tapers to a blunt point. 
The plant increases by means of runners in the mud and this 
My be its chief means of reproduction. The plants are dioecious 
(Gr. two houses) i.e., the male and female flowers are on separate 
plants. It is thought that the male plants have rarely, if ever. 
