MADEIEA. 23 



siognomy 



of vegetation. At the Cape, on the other hand, the species of 



Erica 



spicuouslj abundant, nor cover much ground. The large Sem- 

 pervivums of Madeira (^. glutinosum and tdbulceforme) remind 

 one of the Grassulacew of South Africa, and are perhaps in reality 

 the closest link between the two floras. 



The Clethra arhorea^ an outlying species of a genus otherwise 

 entirely American, is very remarkable. The Vaccinium, which is 

 one of the most characteristic plants of Madeira, likewise deserves 

 notice, on account of the rarity of that genus in Africa. Four 

 species indeed are recorded from IMadagascar, but not one, as far 

 as I know, from the continent of xlfrica, Vaccinium indeed is 

 principally an American genus*, though not as strictly so as 



Clethra. 



The Madeira flora, at least the non-European element of it, 

 has much of a fragmentary character ; made up of a few species 

 from each of a great number of families and genera, none (unless 

 perhaps the Ferns and the Cichoracecc) having any remarkable 

 numerical preponderance. Moreover, the families richest in species 

 are not (with the exception of the Ferns) those which have the 

 greatest influence on the physiognomy of the vegetation. In the 

 flora of the Canaries, on the other hand, there is a much more 

 decided preponderance of particular families and genera. 



3. The plants composing the third portion of the Madeira 

 flora, namely such as appear to be immigrants from tropical 



countries, or from the southern hemisphere, are comparatively 

 few in number, but several of them are conspicuous from their 

 abundance. Among the number are Bidens leiicantha, Ageratum 

 conyzoides, Coimnelyna agraria (?), Gowphocarpus fruticosus, Pe/i- 

 nisetum ccncliroides, Solanum Fseiido-copsicum, Cassia bicapsularis, 

 Aviaryllis BeUadonna, Sida rliomhifoUa, Achyranthes argcntea, 

 Chenopodium amhrosioides ; not to mention others more evidently 

 and recently introduced (see pp. 4, 5). Most of tliose above 

 enumerated are plants widely diff'usedt over tlie warmer parts of 

 the world, and several possess evident facilities for spreading 

 themselves, either by the appendages of their fruits, seeds, or in- 

 florescence, or by their rooting stems. 



Seeing the rapidity with which exotic plants of late introduction 



Out of 85 species enumerated by DeCandoUe, 62 are peculiar to America, 

 North or South. 



r 



t The Amaryllis is an exception. 



«k 



