196 : MONOCOTYLEDONES. 
MONOCOTYLEDONES. 
Series I. MICROSPERMZ. 
Order CXXXVIII. HYDROCHARIDE. 
Hydrocharidee, Benth. et Hook. Gen. Plant. it. p. 448. 
Freshwater and marine aquatic herbs, inhabiting temperate and tropical regions. 
About forty species are known, belonging to fourteen genera. Several species not 
hitherto recorded probably exist within our limits, among them Elodea canadensis, 
Michx., which is widely dispersed in America and now common, though originally 
introduced in Europe, and the very widely dispersed Vallisneria spiralis, Linn. The 
marine genus Thalassia may also be represented on the coast. 
1. LIMNOBIUM. 
Limnobium, L. C. Rich. in Mém. Inst. Par. 1811, pp. 32 et 66, t. 8; Benth. et Hook. Gen. Plant. 
ii. p. 452. 
An exclusively American genus of about four species, floating in fresh water, and 
ranging from Lake Ontario to Peru and Brazil. 
1. Limnobium stoloniferum, Griseb. Fl. Brit. W. Ind. p. 506? 
Jalambicea repens, Liav. et Lex. Nov. Veg. Descr. il. p. 12? 
SoutH Mexico, valley of Mexico (Schaffner, 484). Hb. Kew. 
Order CXXXIX. BURMANNIACEZ. 
Burmanniacee, Benth. et Hook. Gen. Plant. iii. p. 455. 
Delicate annual or perennial herbs, often leafless and coloured ; that is, not green. 
Ten genera, comprising between fifty and sixty species, which are dispersed over the 
warmer regions, and extend to China and North America. Judging from the distri- 
bution of the genus Burmannia, it is probable that other species remain to be discovered 
in Central America. Thus Burmannia capitata, Mart. and B. biflora, Mart. range from 
Carolina to Florida, and through the West Indies (from Cuba to Trinidad) to Brazil. 
1. APTERIA. 
Apteria, Nutt. in Journ. Acad. Sc. Philad. vii. p. 64, t. 9; Benth. et Hook. Gen. Plant. iii. p. 458. 
Three forms have been published as species, but they seem to be varieties of one. 
