THE GERMINATION OF HIPPURIS VULGARIS, 443 
The Germination of Hippuris vulgaris L. By R. D'O. Goon, B.A. 
(Communicated by Dr. A. D. Rexpie, F.R.S., P.L.S.) 
(With 3 Text-ligures.) 
[Read 13th December, 1923. | 
ALTHOUGH much work has been done upon the embryology of /lippuris | 
vulyaris L., there does not seem to be any detailed account of the germination 
or of the many interesting features exhibited during the process. Irmisch 
(in Bot. Zeit. xvii. p. 353) refers to it briefly, while Glück (in Wasser- und 
Sumpfgewiichse, vol. iii. p. 257) touches upon one or two points. Further 
details are given by Fauth (in Bot. Cent. xiv. p. 349), but here again the 
account is very incomplete. 
Hippuris vulgaris (Mare’s Tail) is a plant of somewhat uncertain systematic 
position. Bentham and Hooker place it in the family Haloragidaceæ, while 
Engler and Prantl include it in a family of its own, the Hippuridaceæ. It 
is a water plant with a creeping rhizome and erect shoots bearing whorls of 
subulate leaves. The upper portions of the shoots emerge above the surface 
of the water. The flowers, which are protogynous and anemophilous, are 
borne in the axils of the leaves on the aerial shoots. Each flower consists of 
a single epigynous stamen and one carpel, having one pendulous anatropous 
ovule. The fruit is a drupe. The Mare’s Tail is almost cosmopolitan in 
distribution, and occurs fairly commonly over nearly the whole of the 
British Isles. Its morphology and affinities are dealt with in detail by 
Schindler in Engl. Bot. Jahrb. xxxiv. Beibl. 77. Incidentally this writer 
states that fertilization is rare and that ripe fruits are produced only in 
suitable years. . 
The fruits from which the germination was studied were all taken from 
the gizzards of two species of wild duck shot on Loch Spynie, Banffshire, 
Scotland. Four samples were used, three from teal and one from a tufted 
duck. In each case the hard endocarps, together with a little grit, formed 
the whole contents of the gizzards. In all cases the outer fleshy coverings 
of the drupes had been worn away by grinding action witbin the birds, 
Except in one case, the birds had been shot some considerable time before, 
and the fruits had since been allowed to dry naturally. 
These four samples were sown under similar conditions upon a layer of 
mud at the bottom of beakers containing ordinary tap water and left at 
ordinary room temperature, In their dry condition the fruits floated on the 
surface, but within a day or so became waterlogged and sank to the bottom, 
