22 LEMNACEA.A—DUCK-WEED TRIBE 
medicinally since the days of Hippocrates. It has, doubtless, tonic properties, 
and in our own times has proved a successful remedy in fever, even in cases 
in which Peruvian bark has failed. In Egypt it is called Cassabel, and is 
much valued, and the roots have long been imported into this country from 
the Levant, though our own are as good as those of the foreign plants. The 
rootstock is very large, and full of a farinaceous substance, rendered fragrant 
by an essential oil. In Turkey it is made into a sweetmeat, and sold in the 
shops as a stomachic, and is peculiarly prized during the prevalence of any 
infectious disease. It formerly grew on the brinks of rivers about London, 
but Professor Burnett, who remarks that it is consumed in great quantities 
by perfumers and the makers of hair-powder, says that it has been almost 
wholly destroyed in that neighbourhood by their continual maraudings. 
Order XCVIII. LEMNACEAZX—DUCKWEED TRIBE. 
Stamens and pistils in different flowers on the same plant ; flowers 1 to 3 
in a spathe, but without a spadix; perianth none; stamens 1—2, distinct ; 
ovary l-celled; style short ; stigma simple. The order consists of floating 
herbaceous scale-like annual plants, without distinction of stem or leaf. 
1. DucKkwEeED (Lémna).—Spathe membranaceous and cup-shaped ; flowers 
from clefts just below the margin of the frond; anthers 2-celled ; pollen 
rough. Name from the Greek lepis, a scale. 
2. WoLFFIA (/Volffia).—Fronds very minute, rootless, flattened above, 
budding from the cleft base; flowers: produced on upper surface of frond, 
without spathes; anthers without filaments, 1-celled; pollen smooth. 
Named in honour of J. F. Wolff, an authority on Lemna. 
1. DucKWEED (Lémna). 
1. Lesser Duckweed (ZL. minor).—Fronds inversely egg-shaped, and 
somewhat convex beneath; root solitary. This is a plant with which all 
who have in summer-time gazed upon our standing waters are sure to be 
familiar. Lying there in large floating masses, mingling itself among the 
crow-silks and other Conferve, it in some places entirely covers the surface of 
the pool with a mass of verdure; all these common water-plants increasing 
so rapidly in warm weather as sometimes to occasion trouble to the owners 
of the waters. The little fleshy green frond has no distinct stem or leaf ; it 
is nearly flat at the top, but slightly rounded beneath, very thick, and suceu- 
lent, of a bright green colour, sometimes a little tinged with purplish-red. 
These fronds are collected into twos and threes, each one sending down a 
single root. The Duckweeds increase more by buds than by their flowers, 
but this species flowers very commonly in July; its flower is too incon- 
spicuous to be seen, unless carefully looked for. Professor Lindley describes 
this flowering of the Duckweed in the most simple and graphic manner. 
“Tf,” he says, “you will fix your eye attentively upon a mass of it on a still 
sunshiny day, in June or July, you will probably discover exceedingly minute 
straw-coloured specks, here and there, on the edges of the plants ; they have 
a sparkling appearance, and, notwithstanding their minuteness, readily catch 
