176 



scale-like leaves, imbricated in 3 rows, like which there is nothing among mo- 

 nocotyledons. To this maybe added the binary division of the ovarium, which 

 is analogous to that of many dicotyledons, but a very rare structure among 

 monocotyledons. Finally, the vernation of the leaves of Mourera of Aublet 

 (t. 233), and of Marathrum, which is perhaps not distinct, is entirely that of 

 dicotyledons, rather than of monocotyledons. I incline to place the order 

 in the neighbourhood of Piperacese, to which it probabjy approaches more 

 nearly than to any plants hitherto discovered. 



Geography. Natives of still waters and damp places in South Ame- 

 rica and the islands off the east coast of Africa ; 1 species is found in North 

 America. 



Properties. Unknown. 



Examples. Lacis, Podostemum, Hydrostachys. 



CLXIV. CALLITRICHINE.E, 



CALLiTUiCHiNEiE, Link Enum. 1. 7- (1821) ; Dec. Prodr. 3. 71. (1828) ; a seel, of 

 Halorageae. Lhidl. Si/nops. 242. ( 1 829. ) 



Diagnosis. Achlamydeous herbaceous dicotyledons, with a 4-celled 

 ovarium, and solitary peltate seeds. 

 Anomalies. 



Essential Character — Flowers usually unisexual, monoecious, naked, with 2 

 fistular coloured bracte*. Stamen single ; filament filiform, furrowed along the middle ; 

 anther Temiorm^ 1 -celled, 2-valved ; the valves opening fore and aft. Ovarium solitary, 

 4-cornered, 4-celled ; ovules solitary, peltate ; styles 2, right and left, subulate ; stigmas 

 simple points. Frtiit 4-celIed, 4-seeded, indehiscent. Seeds peltate; embryo inverted in 



the axis of fleshy albumen ; radicle very long, curved, superior ; cotyledons very short 



Small aquatic herbaceous 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 precisely the same nat.ure as 

 that borne by Lemna to monocotyledons : they each exhibit the lowest degree 

 of organisation known in their respective classes." Mr. Brown considers it 

 allied to Halorageae; an opinion in which I concur, without adopting Decan- 

 dolle's explanation of the structure of the flowers ; but at the same time I 

 confess that this affinity is less strong than could be wished; is it not rather 

 an anomalous form of a reduced Euphorbiacea, or is it related to Podostemeae? 

 All this is still a problem. 



Geography. Natives of still waters in Europe and North America. 



Properties. Unknown. 



Example. Callitriche. 



CLXV. CERATOPHYLLE^. 



Ceratophylleje, Dec. Prodr. 3. 73. (1828) ; Lindl. Synops. 225. (1829.) 



Diagnosis. Apetalous dicotyledons, with definite pendulous ovula, 

 solitary flowers, a 1 -celled ovarium, and many-parted calyx. 

 Anomalies. 



Essential Character. — Flowers moniKcions. Ca/ya^ inferior, many-parted. Male: 

 Stamens from 12 to 20; filaments wanting ; anthers 2-celled. Female: Ovarium superior, 

 1-celled ; ovule solitary, pendulous ; stigma filiform, oblique, sessile. Nut 1-celled, l-seede<l, 



