248 APPENDIX. 



Cactaceaj. On the authority of the former they ascend to nearly 15,000 feet near 

 the equator. As the altitudes of several of the higher mountain species are given in 

 another place (in the sketch of the mountain-flora of Mexico, p. 286), it is unnecessary 

 to give the particulars here. The nature of the strata in which cactuses grow is as 

 various as the localities they inhabit. Some nourish in the sands of the sea-shore ; 

 others in clay ; others in loam ; others in sandy and stony wastes ; others in grassy 

 pastures ; whilst many grow on rocks or in crevices of rocks. In some districts they 

 grow associated with other plants, forming a mixed vegetation ; in others they have 

 almost or quite exclusive possession of wide areas. Ehrenberg, who nearly half a 

 century ago spent many years in Mexico, chiefly in the States of Mexico and San Luis 

 Potosi, and was specially engaged in sending cactuses to Europe at a period when they 

 were greatly in vogue among cultivators, mentions particularly the Mesillas near the 

 Kio Grande Aquicalco, the Cardonal, and the valleys of Zimapan and Ixmiquilpan as 

 belonging to the latter category. 



Umbelliferce. 

 The great development of the genus Eryngium is the main feature of this order in 

 Mexico ; but we refer to it here more especially to direct attention to the imperfectly 

 known plants which we have described under the names Asteriscium flexuosum (vol. i. 

 p. 559, t. 32), and Oreomyrrhisl gracilipes and 0.1 planipetala (i. pp. 567, 568, tt. 33, 

 34). Although the specimens are insufficient to determine the genus with certainty, 

 the plants are so wholly distinct from anything previously described that they were 

 figured for the purpose of bringing them into notice. Ottoa cenanthoides is a very 

 singular monotypic member of this order inhabiting the Andes of Mexico and Central 

 and South America, at elevations of 10,000 to 13,000 feet. It is a low herb with 

 fistular, jointed leaves. 



Caprifoliacece. 



Associated with the widely-diffused genera Sambucus, Viburnum, and Lonicera we 

 have the endemic monotypic Microsplenium, the peculiarly North- American Symphori- 

 carpus, and the distinct genus Abelia, which is common to the Himalayas, China, 

 and Japan. 



Bubiacece. 



This order stands third from the largest order of phanerogams, with about 340 

 genera and between four and five thousand species, generally dispersed, except in the 

 coldest regions. Our numbers are : — seventy-four genera ; nine endemic and forty-five 

 others restricted to America, while fourteen range widely; 385 species, 295 of which 

 are endemic and eighty-eight others restricted to America, leaving only two that extend 

 beyond, namely, the widely-spread Geophila reniformis and Nertera depressa, which 

 also inhabits the Andes and southward to Fuegia, Tristan da Cunha, and Australasia. 



