238 APPENDIX. 



tutes the tribe Fremontieae * ; and, apart from the oblique staminal tube and elongated 



anthers overtopped by the long connective, there is little to distinguish the two genera. 



Indeed Baillon has united them under the earlier generic name Cheiranthodendrum, a 



name given by Larreategui in a botanical description of the Mexican tree, of which 



there is a French translation by Lescallier, though we have seen neither the original 



nor the translation. It appears, however, that Larreategui sufficiently described and 



figured the plant under the name Cheiranthodendrum pentadactylon, and there seems 



to have been no justification for the change in the name made by Humboldt and 



Bonpland. 



Butacece. 



Several interesting facts are disclosed in connection with the distribution of this order, 

 which numbers in our region fourteen genera, six of them endemic in Mexico, and five 

 others restricted to America ; and twenty-six species, whereof nineteen are endemic and 

 the rest peculiar to America. No fewer than five of the genera are monotypic ; four 

 of these being endemic and the fifth extending into New Mexico. There is one species 

 of Peganum inhabiting North and New Mexico ; and one species of Thamnosma is 

 endemic in South Africa and one in Socotra, while the others are natives of North 

 Mexico and the country to the north, from Texas westward to California. Excluding 

 the Diosmeee, which are peculiar to South Africa, and the Boroniese, which are wholly 

 Australasian, all the tribes of the Rutaceae are represented. 



Leguminosce. 

 Taking the numbers given in Bentham and Hooker's 'Genera Plantarum,' the 

 Leguminosae comprise 5*3 per cent, of the genera and 6*8 per cent, of the species of all 

 flowering-plants. Of course these figures can only be regarded as rough approximations, 

 yet they doubtless represent very nearly the correct proportions. The Leguminosae are 

 almost universally dispersed, the suborder Papilionaceae reaching the alpine and arctic 

 limits of phanerogamic vegetation ; the Caesalpinieae and Mimosa? being nearly confined 

 to tropical and subtropical regions. In New Zealand, however, the order is exceedingly 

 sparsely represented, and it is altogether absent from the antarctic islands. Furthermore, 

 in remote oceanic islands Leguminosae are absolutely unrepresented by native species, 

 especially in those islands whose shores are unfavourable to colonization by drift seeds, 

 or they are represented almost exclusively by species found elsewhere, and chiefly by 

 those having a wide range, which is evidently very largely due to oceanic currents. 

 This is noteworthy, as being the converse of what obtains for the Compositse under 

 similar conditions. The Leguminosae of Mexico and Central America comprise 27 per 

 cent, of the genera and 14-5 per cent, of the species of Leguminosae in the whole world, 

 and they constitute 8*1 per cent, of the species of flowering-plants within our limits. 

 This last figure seems rather low, and the actual number of species (944) affords a more 



* Dr. Asa Gray has recently raised this tribe to the rank of a natural order. 



