L E I\I N A C E ^ OR DUCKWEEDS. 
By W, Woolls, Ph.D., F.L.S. 
I think that the order of Lemnacem has not been fully investi- 
gated in N. S. Wales, and that more diligent observation will 
reveal species which have hitherto escaped the notice of collectors. 
As the order consists of small floating plants, some with, and 
some without roots (usually found in ponds or stagnant waters, or 
by the side of rivers and creeks), such objects may easily be over- 
looked or regarded as fragments of larger aquatic plants. Mr. 
Bentham and Baron Mueller [Flora Aust. Vol. VII. p. 161), have 
arranged the species in two genera, Wolffia and the former 
being of the simplest form and destitute of any fibres or roots, 
and the latter rather larger and emitting from its under surface 
one or more fibres or roots. Sometimes the whole surface of a 
pond is covered by the larger species of Lemna, and from them 
assumes a bright green appearance ; but Wolffia is not so common, 
and occurs generally amongst other floating weeds, or is seen as 
green, somewhat globular, specks on the surface of still waters. 
When Vol. VI [. of the Flora was published, Wolffia had not 
bf;en found in N. S. Wales, but the writer of this paper collected 
it subsequently in a lagoon near Richmond. This .species was 
referred by Mr. Bentham to W. arrhiza (Wimm ; Ilegelm.), a 
species common to Europe and India, and found of late years in 
Britain ; but Baron Mueller considers it distijict from that species, 
and in his “Census of Australian Plants,” calls it IF. Michelii 
(Schleid.). In a plant so small (the frond beiilg only half a line in 
diameter) there is much difiiculty in examining the fructification 
and hitherto that of the Australian species has not been ascertained, 
so that even now there may be some donl»t as to its specific name. 
In the European species, which diflius somewhat in size and 
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