DIMORPHISM IN FLOWERS OF MONOCHORIA VAGINALIS. 147 
European Conifer, should exist in the writings of the Greeks, 
and that it should not have attracted the attention of any other 
modern traveller than the distinguished botanist to whom we 
owe its discovery in Europe. 
Further, the bearing of this fact in geographical distribution 
upon our modern speculations as to the origin and migration of 
existing species is indeed most suggestive; and that a plant so 
well marked should have disappeared over an area of 2200 miles, 
and yet retained its characters apparently unaltered during the 
ages that have elapsed in the interval represented by this extine- 
tion, and regardless of the vast geographical and climatal changes 
that must have determined its present limitation, is one of the 
most interesting problems that has ever been unfolded to us by 
the history of any European tree. 
Dimorphism jn the Flowers of Monochoria vaginalis. By Joun 
Kıkk, M.D. Communicated by the President. 
[Read April 7, 1864. ] 
Tuıs plant is found in the shallow lagoons of the Zambesi, and in 
mode of flowering presents two very distinct forms. The usual 
inflorescenee is a spike 3-4 inches long, with a membranous 
spathe at base, arising from the sheathing petiole of the leaf. At 
the time of flowering this is raised above the surface, again 
descending to mature its fruit. 
The second form of inflorescence consists of a solitary, almost 
sessile flower, produced at the base of the leaf-stalk, and included 
in its sheath. This is never raised above the surface of the water. 
In addition, each flower is protected by a short sac, formed of the 
membranous spathe, without any opening or fissure; within this 
flowering and fecundation go on ; nor is it until after the capsule 
has become enlarged that this sae is ruptured. 
The perianth consists of a single three-toothed ring, having on 
the inner surface of one of its segments a solitary stamen, two- 
celled, and opening by longitudinal valves. The ovary presents 
no difference, but resembles that of the normal flower; the style, 
however, is almost obsolete; the three stigmatie surfaces almost 
sessile at the apex of the ovary, and directed to one side. No 
marked difference is to be observed between the ripe capsules; 
N 
