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OX THE STRUCTURE AXD AFFINITIES OF 
CALLITRICEACEM. 
By B. Clarke, F.L.S., etc. 
The species of CallUncJie are small lierbaceous plants, vvhicli are 
perhaps terrestrial rather thnu aquatic, as they grow more luxuriantly 
and produce much more seed out of the water on the maro-lus of rivers 
and ponds, than when they grow immersed, and they will grow with 
their usual vigour and fruit abundantly in a flowei^pot. In habit they 
resemble Portulace^s and Car\fop1iyllace(£^ C. venm when growing out 
of water being much like Montia fontana, and C. pedimcnlata when 
growing on banks becomes tufted, much like a Sagina or Stellarla, and 
in the venation of their leaves they also agree with CaryopJiifUace^. 
They further agree with CaryopJiyllace^, and with the nearly allied 
Tdragoynacece, in the surface of their stems (especially wheu the plant 
grows out of the water) having a crystalline appearance, which is 
owing to its being covered with crystalline glands. Tliese have been 
very accurately described by Dr. E. Lankester (Linn. Proc. vol. ii. 
p. 94), and require no further notice, and are in all probability, as he 
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suggests, analogous to hairs. In Tetragoniacece, as in CallUricJie, they 
occur thickly on the young branches, and more sparingly or scarcelv 
at all on the leaves, and I have no doubt about their identity, those of 
Tetragoniacef^ difter:ng in being globular, so that they have not the 
stellate appearance of those of CalUtricJie, 
In C. verna there is a decided tendency in the flowers to become 
polygamous, as the stamen and ovary in the hermaphrodite flowers are 
neither of them smaller than usual. The stamen in the hermaphrodite 
flower is remarkable for being posterior wituout any inclination to 
either side, a very rare occun-ence; and it is precisely hypogynous, the 
filament being attached partly to the receptacle, and in a slight degree 
to the base of the short stalk which supports tlie ovary. The anther 
has been described as having but 1 cell, but in C, pednrienlala it is 
2-celled, at all events nearly up to the peri^>d of maturity, so that the 
pollen can be removed from one of the cells, and the firm liitervenino- 
membrane distinctly seen; in the 1-celled anther of C. terna, there- 
fore, the two cells have become confluent. In its dehiscence the 
anther of C. verna closely resembles that of Crmpi/Iosiacli^s abbreviata. 
