Dissimilar though the states of this plant here brought together are, no one who has collected them together can doubt their all belonging to one species, which, however, seldom fruits.
M. Fries states his conviction of the probability that all the European Ramalinee are varieties of one species, an opinion in which we certainly concur, and we would further add many of the Exotic (except R. inanis) to it. The above varieties certainly all belong to one species, as abundant in Cape Horn and Fuegia as the ordinary states of R. scopulorum are in Europe, and, however unlike some of these forms are to the English plant of that name, the one called a here, and which is the only one that fruits, is in no way to be distinguished from that plant. Considering how plastic the Lichens are in form and texture, and how amenable to the different climatal conditions, it must be admitted that if the R. scopulorum of England were to inhabit the maritime rocks of the Falklands, its aspect would be changed ; the humidity of the atmosphere near the sea of these islands, being much greater than that of similar situations in our own country. Again, the locality inhabited by the var. a., namely, rocks at a considerable elevation and distance from the ocean, possesses a climate more assimilated to the British habitats of R. scopulorum than are the moist rocks at a lower level, and hence it is only natural to suppose, that there the Falkland Island form would assume the English. Lastly, the universally acknowledged difficulty of defining the European species, and the singular abundance of forms of the genus exactly similar to these in all parts of the world, between Lat. 60° N. and 57° S., together with the fact that many other Lichens are equally protean and widely distributed, are all arguments in favour of the Antarctic species having a common origin with other forms of the genus inhabiting the Arctic, Temperate, and Tropical regions.
The genus Ramalina, in the Arctic zone, attains the parallel of 69°, on the shores of the Polar Sea in North America, and of Lapland in Europe.
4. CETRARIA, Ach.
1. Cetbabia Idandica, Ach.; Lick. Univ. p. 509. Engl. Bot. 1. 1330. Hab. Hermite Island, Cape Horn; amongst moss on the tops of mountains only, 1,500-1,700 feet, barren.
One of the most Arctic of plants, having been collected on Ross Islet, the northernmost known land in Em-ope (81° N.), and in Melville Island (76°), on the limits of Arctic American vegetation. It inhabits the level of the ocean only within the Arctic circle, or in the extremely cold plains of Central Russia (as Moscow, 55° N.) Dahuria in Asia, 50° N., and in North America (as Labrador, 55° N.); thence, in progressing south, it asceuds; attaining the tops of our Scotch Alps, 4,000 feet (56° N.), about 10,000 feet on the Swiss Alps (46° N.), 9,000 feet on the top of the Pyrenees, and 4,000 feet on the mountains of North Carolina and Virginia (in 36° N.). The last locality is the lowest latitude it attains in the Northern Hemisphere ; in the Southern it re-appears only on the extreme point of America, and there is confined to the pinnacles of the very highest mountains. There is perhaps no vegetable common to both hemispheres more typical of extreme cold than this Lichen, which is further interesting from being the reputed cure for consumption, and the only plant of that order extensively used in medicine.
2. Cetraria glauca, Ach.; Inch. Univ. p. 509. Mont, in Voy. ait Pole Sud, Bot. Crypt, p. 194.
Hab. Hermite Island, Cape Horn; top of Mount Kater, 1,700 feet; on rocks, sparingly. Straits of Magalhaens, I? Urville and Jacquinot.
This, again, is an'instance of the re-appearance of a Northern and Arctic Lichen in the Southern Hemisphere only under Antarctic skies. The C. glauca finds its principal parallel in Scotland, central and northern Europe, and sub-arctic America, wandering as far south as the Swiss Alps and mountains of the Canary Islands. It is not nearly so Arctic as the O. Idandica, not being found in Spitsbergen or Melville Island, or, according to Richardson anywhere to the northward of 54° in Arctic America. Wahlenberg states it to be rare in Lapland.
