Che American GAater GAeed, Anacharis 
Alsinastram, Bab.: Hts Structure and Gabit; | 
with some Hotes on its introduction into Great 
Britain, and the causes affecting its rapid spread 
at first, and apparent present diminution. 
WITH PLATE. 
BY J. D. SIDDALL. 
Read before the Botanical Section of the Chester Society of Natural 
Science, March 8th, 1883. 
LTHOUGH it is not yet half a century since the first 
introduction of Azacharis Alsinastrum from America, its 
subsequent spread has been so rapid that it is now one of the 
commonest plants in Great Britain. The circumstances attendant 
upon this remarkable increase, and the physical conditions and 
structural peculiarities which have combined to bring it about, 
present questions of the deepest interest, and which I here 
propose briefly to discuss. 
Anacharis Alsinastrum, Bab., the American Water Weed, or 
ater Thyme as it is sometimes called, is a Monocotyledonous 
plant belonging to the Natural Order, Hydrocharidee. Two 
other British plants only belong to the same order, viz.:— 
Hydrocharis morsus-rane, the Frogbit, and Stratiotes aloides, 
Water-soldier. 
Frogsir is common everywhere in our district. Its round, 
kidney-shaped floating leaves and pretty delicate white flowers 
form a complete covering over the surface of many ponds and 
sluggish waters. It rarely produces seed, and is chiefly re- 
produced by compact ‘‘ winter-buds,” which become detached 
upon the decay of the parent plant, and remain dormant through 
the winter, either floating on the surface or sinking to the 
bottom, and renewing the plant each spring. The long, simple 
unbranched roots, thickly covered with root hairs, render the 
plant a very striking one in an aquarium; and the cells of the 
transparent stipules show well the phenomenon of rotation of 
the protoplasm. 
WATER-SOLDIER is much more rare, and almost unknown in 
