DISTRIBUTION OF THE MOEE PEOMINENT NATUEAL OEDEES. 237 



Marcgraviacece. 



This interesting group of shrubs and small trees is peculiar to America, and may, for 

 our purpose, be regarded as an independent natural order ; in fact its claims to this 

 rank are perhaps greater than those of some others generally recognized as such. The 

 highly curious and various "nectar-cups" of these plants deserve a more thorough 

 investigation than they have yet been subjected to, inasmuch as their economy is still 

 imperfectly understood *. Four genera and about forty species have been described ; 

 their greatest concentration being in Brazil, though they range from Mexico and the 

 West Indies to Brazil, Peru, and Bolivia, as many as ten inhabiting Peru. Three out 

 of four of the genera occur within our limits, and the same three are represented in the 

 West Indies, one being generally spread from Cuba to Trinidad, while the other two 

 are only in the latter island. 



Temstrcemiacece. 



The only member of this order besides the tribe Marcgraviacese deserving special 

 mention here is the singular monotypic Pelliceria, an inhabitant of the mangrove-swamps 

 in southern Panama and Colombia, and in popular parlance it is a kind of mangrove. 

 While possessing the structural characters of the order it exhibits the habit and vege- 

 tative development of the Ehizophorese or true mangroves. 



Malvacece. 



After making a very large reduction of doubtful and obscure species this order stands 

 twelfth in numerical strength, and nearly half of the genera are represented in Mexico 

 and Central America. The only endemic genera are the monotypic Ingenhousia and 

 Montezuma ; and half of the remainder extend to other countries, most of them being 

 generally dispersed. Just about half of the 182 species are endemic, and fourteen are 

 of wide distribution. Noteworthy Malvaceae in our own region are the solitary species 

 of the peculiarly Tropical American small arboreous genera Ochroma, Chorisia, Hampea, 

 and Cavanillesia. 



Sterculiacece. 



This order includes a considerable number of curious forms belonging to the various 

 tribes into which it has been subdivided, as for example Quararibea, the monotypic 

 Bemoullia and Cheirostemon, the large African genus Hermannia, represented in the 

 Texano-Mexican region by three or four species, and the singularly formed American 

 Ayenia. Among these the celebrated Cheirostemon of the uplands of Mexico and 

 Guatemala is the most interesting ; it abounds in the forests at altitudes of 7000 to 

 9000 feet, and in some places ascends to 10,000 feet. Together with Fremontia Cali- 

 fornia, which inhabits dry hills from Pitt Eiver to San Diego in California, it consti- 



* In the ' Gardeners' Chronicle,' n. s. xiv. (1880) pp. 11-13, we have brought together all the available 

 information on this subject, with illustrations of all the principal modifications of the nectar-cups. 



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