36S FLORA ANTARCTICA. [Fuegia, the 



Affinis C. externa, Good., qua? perigyniis eostato-nervosis, glaucis, squamis masculis rnutieis, foliis, bracteisque 

 patentibus vel recurvis, ssepe involutis, differt. Boott. 



12. Caeex trifida, Cav., vicl. Fl. Antarct. Pt. 1. p. 89. 



Hab. Cape Tres Montes, C. Darwin, Esq. ; Falkland Islands, abundant, I)' Urville, Capt. Sutivan, 



j. n. h. 



A very noble species, abundant in the Falkland Islands, growing with, and emulating in size, young Tussock 

 grass. Mr. Darwin alone has gathered it on the American continent, and he only at Cape Tres Montes. Its 

 confined range is very singular, for it can scarcely have been overlooked in Fuegia or the Strait of Magalhaens, had 

 it existed there ; and it is also probably the only plant common to New Zealand and the Falkland Islands, not found 

 abundantly in Tierra del Fuego. 



Carex trifida affords a remarkable instance of apparent caprice in its choice of habitat ; for though common 

 in the Falklands, along with the Bacti/Us caspitosa (Tussock grass), and though there these grow in company, 

 and under precisely the same conditions, yet the Tussock grass in America only appears in the southern extreme 

 of Fuegia, where it is unaccompanied by Carex trifida ; whilst the latter is confined to a latitude eight hundred 

 miles north of Cape Horn. There is nothing whatever in the climate or soil of any part of western South Chili, 

 or Fuegia, that can be pronounced unfavoiuable to the growth of this Carex, whose absence there naturaUy 

 leads to the question, how is its presence in Cape Tres Montes and the Falkland Islands to be accounted for ? 

 did it originate in each of these two isolated localities ? was the seed transported over the intervening land, by 

 an agent whose operations were limited to the eastern, and western extremes only of Antarctic America? or, 

 have the individuals that once tenanted the intervening land, been destroyed ? Any one of these hypotheses is at 

 first sight plausible, and the first, perhaps, the most so, New Zealand being a third, and far more remote, habitat 

 for this same species, which may thus be supposed to have had three separate origins. Such a question should 

 not be discussed with reference to a single species, but as one which concerns all organized nature, whose pheno- 

 mena are amenable to general laws. Hypotheses, adopted to account for exceptional cases, if not viewed in 

 reference to the general rule from which these exceptions deviate, are generally fallacious ; and however much so, 

 they still are apt to be magnified into laws. If we knew only such plants as are sporadic (the term given to species 

 which inhabit unconnected and remote localities) we might, perhaps, be justified in assuming it as an axiom, that 

 individuals of a species have sprung, at isolated localities, from as many similar parents : the cases which appear to 

 demand this solution are, however, exceptions in Botanical Geography. 



The study of the distribution of any one species or genus, or of the Flora of any one country, does not afford 

 scope enough for investigating satisfactorily such a subject as the origin of the individuals of plants. If species, 

 genera, and small natural orders were sporadic, recurring wherever climate and soil presented similar conditions, 

 several points of origin for the same species might be assumed. But it is not so : species, genera, and orders are dis- 

 tributed within geographical limits, according to their extent : the great mass of individual plants in the one case, and 

 of forms in the other, appear to have sprung from single centres, in the former case from a common parent, and to 

 have radiated from one point to greater or less distances around it, in proportion to the facilities for migration and 

 absence of checks to diffusion. The explanation of exceptions to this prevailing rule must then be sought in some 

 natural cause, capable of counteracting the general law, and not what, if adopted for the case of one species, 

 must be conceded with respect to all, and consequently force us to conclude that two classes of agents are required 

 to effect one object, namely, the dispersion of vegetables. 



7. TJNCINIA, Pers. 



1. Uncinia tenttis, Poepp., Sgnops. Plant. Am. Austr. vol. iii. n. 240. Kunze, Synops. der Reidgr. 

 t. 21. Kunth, En. Plant, vol.ii. p. 525. 



