DISTRIBUTION OF THE MOKE PEOMINEOT NATUEAL OEDEES. 257 



Scrophularinece. 

 This order is generally spread, yet it is perhaps nowhere so strongly represented 

 generically as in Mexico, where there are forty-two genera, nine of which are endemic; 

 twelve others are wholly American, and twenty-one extend to other countries. The 

 last number is proportionately higher than in the majority of the large orders of 

 dicotyledons. The total number of genera in the order is about 170 and the species 

 are estimated at nearly 1900. A. DeCandolle * calculated the percentages in numerous 

 floras, large and small, of several of the larger orders, among them the ScrophularineEe. 

 In the first part of Bentham's 'Plantae Hartwegianee,' collected in Mexico and Guate- 

 mala, and numbering 630 species, chiefly from temperate and subtropical regions, he 

 found that this order constituted 6 per cent. ; but so high a proportion can only be 

 regarded as accidental, though no doubt it is very much higher for these regions than 

 for the entire area. Martiusf calculated that the Scrophularineee constituted about 

 1-5 per cent, of the species of the Brazilian phanerogamic flora, and this is exactly the 

 proportion for the whole of Mexico and Central America. Six of the endemic genera 

 are monotypic ; and equal numbers of the whole extend to eastern and western North 

 America; but those of north-eastern extension contain a larger proportion belonging 

 to genera of extra-American distribution. The Andine and Antarctic American genus 

 Calceolaria has its northern limit in South Mexico. This is also represented in the 

 Falkland Islands and New Zealand. Pentstemon, with the exception of one species in 

 North-eastern Asia, is exclusively American and chiefly western ; and of the twenty- 

 one species in Mexico two reach Guatemala. The South-African genus Phygelius, 

 however, is so near Pentstemon that if it were from the same country it would probably 

 have been put in the same genus. The other large genera are, Castilleja, which has a 

 wide range in America and one of the species is also found in North-eastern Asia, and 

 the endemic Lamourouxia. Coming to the species, we find that only nine out of 170 

 extend beyond America, and 103 are endemic within our boundaries. 



Gesneracece. 

 All the tribe Gesnereae and the subtribe Columnese of the tribe Cyrtandrea? are 

 American, ranging from South Mexico and the West Indies southward to Chili and 

 South Brazil. It is true that Achimenes scheerii is recorded from Chihuahua in our 

 enumeration, but on reference to the place of publication we find that it was received 

 through Mr. Potts of Chihuahua ; therefore it is possible, in fact most probable, that 

 he obtained it from South Mexico, as it would otherwise be widely isolated from the 

 rest of the order. Twenty genera of this group are Mexican or Central American and 

 three of them are endemic in South Mexico and Guatemala; and 133 out of 144 



* 



Geographic Botanique, ii. pp. 1189-1250. 

 t Flora Brasiliensis, Scrophularinea;, p. 332. 



