THE AMERICAN WATER WEED. 129 
in colour, and are produced singly in the axils of the upper 
leaves. The ovary is small, oval, and enclosed within a two- 
lipped narrow spathe, above which the long, slender perianth 
tube rises to a length of from two to eight inches, by not more 
than ;,"" of an inch in diameter. This expands on the surface of 
the water into a flower of six segments, three outer boat shaped 
and three inner reflexed. ‘There are generally from three to six 
abortive stamens, some of which may occasionally be found 
producing anthers and pollen. ‘The pistil consists of a unilocular 
inferior ovary, developing a few straight ovules on three parietal 
placentas, a long thin style, adherent to the perianth tube; sur- 
mounted by three short obtuse papillose stigmas. 
Practically, the plant is dicecious, and until 1880 it was 
believed that we had only the pistillate plant in Great Britain ; 
but in that year the late Mr. Davip Dovetas found the staminate 
plant flowering freely in a pond on the Braid Hills, near 
Edinburgh. This differed very slightly in appearance from the 
female plant. The place of the staminodes and stigmas was 
occupied by a central column of six to twelve stamens united by 
their filaments, but with free anthers; and the perianth tube 
was longer and even more slender than in the female flowers, 
ultimately narrowing and breaking off, and so allowing the 
flower with its supply of stamens and pollen to float freely on 
the surface of the water. Thus calling at once to mind the mode 
of fertilization so well known in the allied South European 
genus Vallisneria spiralis. 
There is no published account of the perfect fruit or fertile 
seeds of Anacharis ever having been developed in Great Britain, 
The obvious inference is, therefore, that all the immense 
quantities of this plant at present flourishing here have arisen 
by development of fragments detached from the plant originally 
introduced. 
When we remember that half a century has not yet elapsed 
since the appearance of the first fully authenticated record of the 
occurrence of Anacharis in British waters, and then call to mind 
that at the present time it has extended not only over the British 
Islands, but also over the greater part of the Continent of 
Europe,—and further, that in point of mere quantity Anacharis 
at one time probably nearly equalled in amount all other British 
aquatic plants put together,—it will be obvious that a problem 
is here presented in development entirely without parallel in the 
higher vegetable kingdom. 
Originally a native of North American rivers, and there by 
no means a troublesone weed, it has been from there introduced 
into Great Britain in some mysterious and quite unknown 
manner. The conjecture which seems to obtain most favour is 
that a sprig or seed of Anacharis was unwittingly brought over 
to this country and placed in our rivers sticking in a crevice in a 
log of American timber. Once so introduced, it seemingly at 
