DISTRIBUTION OF THE MOEE PROMINENT NATURAL ORDERS. 245 



affinities of the Turneraceae are with the Passiflorese and Loasaceae. Turnera ulmifolia 

 is now very widely colonized in Asia and Africa. 



Passifloracece. 

 Passiflora is an essentially American genus, ranging from Virginia and Texas through 

 the "West Indies and Mexico to Chili and South Brazil, and numbering upwards of 

 150 species, whereof fifty are within our boundaries, and about twenty of them endemic. 

 The twenty-five species or so in the Old World are widely scattered. Carica and 

 Jacaratia, constituting the tribe Papayese, peculiar to America, are both represented 

 in Mexico. 



Cucurbitacew. 



Out of twenty-four genera six are endemic and six are monotypes, the most note- 

 worthy among the latter being Hanburia mexicana ; and out of ninety-three species 

 sixty-two are endemic, and the only one recorded as extending beyond America is 

 Melothria pendula, which Cogniaux records from near Macao, China. From the 

 locality and other circumstances, it is more than probable that the plant, if actually 

 collected in China, is a colonist there. 



Begoniacece. 



Begonia is a genus of nearly 400 species, widely spread in warm regions, but most 

 numerous in Tropical Asia, Brazil, and Mexico ; absent from Chili, North America, 

 Europe, and Australasia*. In Asia the genus extends into the temperate regions as 

 far north as Peking; and the southern limit is in eastern South Africa. Only two 

 species have been collected in North Mexico — one in San Luis Potosi, and a very 

 distinct one recently in Chihuahua. As in most large genera, the species are local. 

 The only other genera are : — Begoniella of three or four northern Andine species, and 

 Hillebrandia a monotype endemic in the Sandwich Islands. 



Cactacew. 



The members of this order vary in size from the lowly species of Mamillaria, many 

 of which merely carpet the earth or rock, to the gigantic species of Cereus, the larger 

 of which attain a height of fifty to sixty feet, with correspondingly thick trunks. They 

 are mostly destitute of true leaves, but they present an infinite variety in shape and 

 in the hairy and prickly appendages of their stems ; and the flowers are nearly always 

 brightly coloured, even if small, and many of them are large and brilliant in the 

 extreme. Bed and yellow of numerous shades and white, either separately or variously 

 combined, are the colours ; blue being apparently quite absent. 



* Leaves of what may prove to be a Begonia have been collected in North-western Australia. 



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