191 
any additional remark, so long as no more was known of the structure of 
Podostemaceae. It however always appeared to me impossible to concur in 
opinion with Kunth, Richard, von Martins, Arnott, &c. who considered the 
order monocotyledonous ; for the following reasons. In the first place, the 
habit is that of dicotyledons, as for instance Podostemum of a starved pepper ; 
Mourera and Lacis of Ranunculaceae, not only in the resemblance of their 
leaves to those of aquatic Ranunculi, but in that of their flowers to those of 
Thalictrum ; Hydrostachys has its flowers arranged in the way of those 
of Saururus. Moreover the vernation of the leaves of Mourera is that of 
dicotyledons rather than of monocotyledons. These reasons have not appeared 
satisfactory to Bongard, who accordingly adopts the opinion of Martius and 
others ; it is not a little curious, however, that this clever botanist should 
himself have furnished the first and only direct evidence that has yet been 
offered, that Podostemaceee are really dicotyledonous, and consequently that 
he is in the wrong ; for although he calls the embryo, p. 70, monocotyle- 
donous, he represents it t. 3 and 5, as dicotyledonous, as it moreover evidently 
is, from the terms of his own description. 
Geography. Natives of rocks in rivers, still waters and damp places in 
South America and the islands off the east coast of Africa ; 1 species is found 
in North America. 
Properties. Some species of Lacis yield, when burnt, a considerable 
quantity of salt from their- ashes: Schomburgk. 
GENERA. 
Podosteinon, Mich. Mourera, Aubl. (23.) Philocrene, Bong. Hydrostachys, Thou ar. 
? Dicroeia, Pet. Th. Marathrum, Humb. Mniopsis, Martius. Tristicha, Thouars. 
Lacis, Schreb. Crenias, Spreng. 
Alliance V. CALLITRICHALES, 
Essential Character — Carpels several, combined in a solid pistil, single-seeded. 
Floating plants. 
Order CXLII. CALLITRICHACE.E. 
Callitrichine^e, Link Enum. 1. 7. (1821); Lavielle in Ann. Soc. Linn. Par. p. 229. 
(1824); DC. Prodr. 3. 71. (1828); a § of Haloragese. Lindl. Synops. 242. 
(1829). 
Essential Character. — Flowers usually unisexual, monoecious, naked, with 2 fistular 
coloured bracts. Stamens single ; filaments filiform, furrowed along the middle ; anther 
reniform, 1 -celled, 2-valved; the valves opening fore and aft. Ovary solitary, 4-cornered, 
4-celled; oumZcs solitary, peltate ; styles 2, right and left, subulate; stigmas simple points. 
Fruit 4- celled, 4-seeded, indehiscent. Seeds peltate ; embryo inverted in the axis of fleshy 
albumen ; radicle very long, curved, superior ; cotyledons very short. — Small aquatic her- 
baceous plants, with opposite, simple, entire leaves. Flowers axillary, solitary, very minute. 
Affinities. I have remarked in my Synopsis, that “ the affinity of this 
order to other dicotyledons appears to be of the same nature as that borne by 
Lemna to monocotyledons : they each exhibit the lowest degree of organisa- 
tion known in their respective classes.” Brown considers the order aUied to 
Haloragese : an opinion in which there is much plausibility, and in which 
Botanists seem to be generally disposed to concur. The great objection to it 
is this ; Haloragese are a reduced form of Onagracese, with the petals often 
