Digitale Ausgabe

IT will not escape the studious observer of the natural sta-tions of plants, that in the cryptogamous * class of vegeta-

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* Phanogamous plants, are those in which the organs of fructificationare apparent and determinate; cryptogamous plants, those where these|58| bles, the Order of Ferns distinguishes itself from those ofMosses, Liverworts, and Mushrooms, in this particular, viz.that the latter have many species which are owned in commonas well by the north of Europe as by the tropical regions ofboth the Old and New Continents, and not merely as peculiarto the mountains, but likewise as inhabitants of their plains;such are Funaria hygrometrica (twisting cord moss,) Dicra-nium glaucum (white fork moss,) Polytrichum juniperinum (juniper-leaved hair moss,) and the Lichens Verrucaria Perella, Sticta crocata, Parmelia perlata, &c. all which arefound as well on the trees and rocks of the West Indian Islands,the chain of the Andés, the East Indies, and that part of NewHolland which stretches towards the North, as in the Forestsof Sweden and Great Britain. While among ferns a far nar-rower range has been allotted to the species, for with very fewexceptions those of the new and old continents, not only differin the one from those in the other, but in the tropical regionsare manifestly distinct from their co-ordinates of the temperateand frigid zones. In tracing the native stations of the ferns, and the plan oftheir distribution over the face of the earth, I have ascertainedthat of the 1000 species that have been as yet observed, 760belong to the torrid zone, and 240 to the temperate and frigidzones. But when we speak generally of the number of theseplants, the subject presents itself three ways; one, regardingthe relative numbers of the species among themselves, anotherregarding their numbers in relation to the phænogamousportion of vegetation, and a third in regard to the quantityeach species may of itself exist in. Thus Wahlenberg reckons19 species of fern in Lapland, Hoffmann, 40 in Germany,Swartz, 103 in Jamaica, making the proportions of the frigid,temperate, and torrid zones, as they relate to each other in thispoint, as 1, 2, and 5. But the amount of phænogamous plants

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are more or less clandestine and indeterminate; agamous plants,those in which those organs either are not present, or have not beendetected. K |59|in these regions is greatly disproportionate; for in Laplandthere are 514 known species, and in Germany 1884, makingthe proportions 1:25 and 1:48. Whether this relative dis-proportion increases towards the equator or not, is unknownto me; but if it were 1:50, and if the ferns have come in-completely within the view and observation of botanists as thephænogamous portion of the vegetable creation, (which hashardly been the case,*) the result would be, that 5000 phæno-gamous species have been already discovered in Jamaica, and23,000 in the whole of the tropical extent of America. Thedegrees of abundance with which nature has sent forth parti-cular species are manifestly various: at the extremity of Nor-way, on the shores of the frozen sea, ferns, although but fewin species, cover nearly the whole face of the land. Of the 1000 species of ferns recorded by Willdenow, 470grow in the old world; viz. 170 in the temperate and frigidzones, 300 within the tropics; and 530 grow in the NewWorld, viz. 70 in the temperate and frigid zones, and 460within the tropics. I have elsewhere attempted to show, that if we representthe land within the tropics by = 1000, we are to allot it in thefollowing proportions; to

• Africa, .............. 461
• America ............. 301
• New Holland and the Islands in the Indian Sea, 124
• Asia ............... 114

leaving the proportion which belongs to the New World inrelation to that of the Old as 5 is to 7. So that if we did notknow the New World to be of a more humid constitution witha more mountainous surface than the Old, and that the interiorof Africa and New Holland have been far less explored thanthe regions that lie between the Orinoco and the river of the

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* Swartz, who attended diligently to ferns, has only recorded 764 phæno-gamous plants in Jamaica. In Michaux’s Flora of North America 45 fernsand 1575 phænogamous plants have been described. The Isles of Bourbonand France comprehend 137 species of plants.|60|Amazons, we might be led to wonder why the portion ofAmerica, being considerably the least, should have by ⅓ thelargest proportion of ferns. I am fully aware that too much reliance must not be placedon the exactness of the amounts, since it has not been ascer-tained, what proportion of each of the various regions of theearth has been accurately explored; nor what proportion of thetotal of vegetation has escaped the notice of the botanist; norwhether all the different tribes of plants have been investigatedwith equal care. But independent of these doubts, it is clearthat the number of species cannot at all events be less thanthat which I computed. Although the phænogamous plants of tropical Americaare entirely different from the phænogamous ones of the OldWorld, yet the northern portion of America has many incommon with Europe and the North of Asia. Whence itmay be inferred, that at some period those continents havejoined towards the North Pole; and it will be a matterof wonder, that so few European ferns are found in Canada,Pennsylvania, and California; for of such we do not hear ofmore than from 6 to 10 species, as for instance, Ophioglossum vulgatum, (common adder’s-tongue,) Polypodium calcareum, (rigid three-branched polypody.) Aspidium thelypteris, (marshshield-fern, or Lady-fern,) Acristatum, (lesser crested shield-fern) Pteris aquilina, (common brake,) &c.; but then Europealtogether does not contain more than 70 indigenous species offern. Towards the South Pole, the ferns, which grow at the extre-mities of the two continents, differ more than those of the north-ern temperate zone do from each other. The only instancesof any common to all the continent in those regions, that I amaware of, are Davallia pinnata, which grows in Chili and in thePhilippine Islands; and Osmunda barbara, which grows in NewHolland and at the Cape of Good Hope. Hence it is the morestrange that Aspidium aculeatum, (or common prickly shield-fern,) which is the only one among the ferns of the Old Worldthat ranges through several of the zones, extending itselffrom England across Mount Atlas to the southernmost verge |61|of Africa, should not have yet been met with in America.According to Messrs. Forster and Brown, Botrychium Lunaria, (common moonwort) familiar in every part of Germany, covers,in company with the Phleum alpinum, (alpine cat’s-tail-grass)of our country, every rock in Tierra del Fuego. Hymeno-phyllum tunbridgense, (Tunbridge filmy-grass) grows in NewHolland as well as in Ireland, Norway, and Italy. The only instance of a species of the fern-tribe growing bothin the Old and in the New continents, in the torrid as wellas in the frigid zone, in a northern and a southern hemi-sphere, viz. in England, Jamaica, and the Isle of Bourbon, isthe Adiantum Capillus Veneris, (true maiden-hair,) a plantwhich has been commemorated by Hippocrates, Theophrastus,and Dioscorides. It has however been surmised by some thatthe germs of this fern have adhered to the filtering stones usedaboard ships in long voyages, and been thus carried along withthem and disseminated over the world. It is not quite clear, that any fern has been found that iscommon to the tropical regions of both the New and Old Con-tinents. Authors have as yet only suggested three suchinstances, viz. Aspidium punctulatum, A. coriaceum, and Asple-nium monanthemum, which are said to be spontaneous in theWest Indies, the Andés of Peru, Guinea, New Holland, andthe Cape of Good Hope. To these may be added Asplenium falcatum, and Blechnum caudatum, supposed to belong to SouthAmerica and the Islands of Magindanao as well as Ceylon.But I doubt whether the statements concerning these instancesare so well authenticated, as those mentioned above of Hyme-nophyllum tunbridgense, and Botrychium Lunaria. More than half of all the ferns yet observed belong tofour genera only, viz. to Polypodium, (Polypody,) Aspidium, (Shield-fern,) Pteris, (Brake,) and Asplenium, (Spleenwort.)Some types among them seem confined almost entirely to tro-pical lands, as Meniscium, Anemia, Hydroglossum, Mer-tensia, and Schizea: but all the generic types of the northerntemperate zone are found likewise between the tropics. TheNew World alone has no genus of the Fern-tribe peculiar toitself, although many of its phænogamous genera are so; forexample, Cactus, Calceolaria, Alstrœmeria, Bromelia, |62|and others. As for the fern-types Polybotrya, Pleopeltis, and Marattia, so few species of them have been found, that itis highly probable other congeners will be detected in our owncontinent, so that they can hardly be relied on as exceptions. Ferns, which in the northern frigid zone grow along theground in the shade, in the tropical regions, shoot up to thedimensions of trees, vying with the palms themselves in statureand comeliness. These tree-ferns constitute a principal orna-ment of the torrid zone, giving that peculiar character to thespots where they grow, which strikes so forcibly the Europeanstranger by its novelty. The Greek and Roman writers whohave treated of plants, mention in several places, that manywhich in Europe creep along the ground, in hotter climatesbecome trees, making it the more remarkable, that noneshould speak of a tree-fern; particularly as Megasthenes,Aristobulus, and Nearchus, recount among the wonders ofIndian and Ethiopian lands, that there are trees having leavesas large as a shield, a fig-tree that takes root at the endsof its branches, and palms too high for the flight of an arrowto pass over. Theophrastus, Dioscorides, and Pliny, who hastrodden over again the ground of the two first, mention onlyeight or ten species of ferns, none above a yard high. Andwhen a certain sort of fern brought from India is noticed, asbeing known to the philosopher Eresius, no observation isoffered concerning the stature of the stem, attention being onlybestowed on certain medicinal qualities imputed to the plant.So that tree-ferns must have been left unnoticed by the Romansand Greeks, either because in that portion of India, which thearms of Alexander had opened to them, or in Ethiopia andLybia, which they visited in the view of commerce, none areto be found; or because their writers, as was usual in formertimes, left unnoticed all plants which did not recommendthemselves to their attention by the fruit they bore, or the fra-grance of their wood, or their medicinal virtues. Oviedo,the Spaniard, in his history of the West Indies, is the firstwho mentions a tree-fern; for the Filix arborea of Tragus isnothing more than a variety of our common forked spleen-wort, transplanted into a more fertile land. So late as the time of Linnæus scarcely 4 sorts of tree-fern |63|were known, and about 15 sorts of palms; at present we areacquainted with 25 of the former, and 100 of the latter. Thetree-ferns of America are, Cyathea speciosa, C. arborea, C. Serra, C. muricata, C.multiflora, C. villosa, C. aspera, Pteris aculeata, P.villosa, Meniscium arboreum, Aspidium caducum, A. pro-cerum, A. rostratum, Asplenium arboreum, cæt. Of New Holland and the Islands of the Indian Sea; Cyathea affinis, C. medullaris, C. dealbata, C. extensa, Dicksonia squarrosa, D. antarctica, cæt. Of Southern Africa, and the Islands of France and Bourbon. Cyathea excelsa, C. glauca, C. riparia, cæt. The tree-ferns of the East Indies, Cochinchina, the Islandof Madagascar, and the Cape of Good Hope have not yet beenaccurately described. I have not included amongst the arbo-rescent species, Aspidium Arbuscula, Lomaria Boryana, Poly-podium rhizocaule, P. pruinatum, Pteris marginata, &c. becausethey are either climbers, or else shrubby or caulescent plants,with stems not more than three or four feet high. Of thefive new species of tree-ferns observed by M. Bonpland andmyself, Cyathea speciosa is the one which makes the finestappearance, and has a stem 25 feet high. The C. excelsa ofthe Isle of Bourbon is said by Messrs. Du Petit Thouars andBory St. Vincent to grow to the same height. In general, the tropical plants are further advanced towardsthe South Pole than towards the North Pole, a fact whichseems inconsistent with the received opinion of the cold beinggreater in the Southern Hemisphere. In North America andNew Spain, the tree-ferns hardly ever grow beyond the limitsof the tropic of Cancer, while only one species of palm (Cha-mærops Palmetto) advances to Carolina, or the latitude of 37°. In the Southern Hemisphere, on the other hand, Dicksonia antarctica, described by Labillardiére as having a stem near 20feet high, grows in Van Diemen’s Island; nay, another speciesof Dicksonia has been found at Dusky Bay in New Zealand, inthe 46th degree of southern latitude, where in a parallel whichcorresponds with that of Lyons, the trees swarm with Epiden-dra and Dendrobia, vegetable parasites, which constitute the |64|most graceful ornaments of the tropical Flora. Phæno-mena, which excite the more wonder, when we find from theobservations of the celebrated navigators Cook, Entrecasteaux,and Flinders, that the mean annual temperature of this zoneis scarcely equal to 12,5 of the centigrade thermometer.But the great expanse of water in the Southern Hemispherecools the heat in summer and assuages the cold in winter; sothat in the 52d and 53d degrees of southern latitude, corres-ponding to that of Berlin in our hemisphere, the snow meltsnearly every day of the winter, and the centigrade thermome-ter very seldom rises to 11° in the months of January and De-cember, the hot summer months of these regions. Even in the42d and 43d degrees of Southern latitude, owing to the cur-rents of wind that blow from the South Pole, the summers arehardly hotter than at the sides of the mountains of Switzerland:these summers, on the other hand, are succeeded by winterseven milder than those of Rome. Labillardiére never observedthe centigrade thermometer in Van Diemen’s Island risehigher at mid-day than 15-17°,5 in the months of January andFebruary; and Cook in the same parallel, during July, a wintermonth of those regions; never found the degree of cold below8° of the centigrade thermometer. In tropical America, as I have shown in another work, theherbaceous ferns grow in all parts, from the border of the sea,and from the plains, up to the heights of the Andés, althoughbut little below the limits of eternal snow. There are certainspecies peculiar to certain elevations, and each in its zone isunable to transgress that boundary which has been allotted toit. Thus in the mountains of Peru and New Spain, Cheil-anthes marginatus, Acrostichum muscosum, and Hemionitis rufa, grow between the elevations of 1200 and 1600 fathoms:in the same way the Pteris crispa, (rock-brake or curled stone-fern) grows on Mount St. Gothard from above the region ofPines up to the elevation of 1,100 fathoms; and in Lapland,near Enontekies, to that of 300 fathoms; so that in Switzer-land, its highest station is scarcely 280 fathoms removed fromthe limits of eternal snow, and in the North of Norwayscarcely 100 fathoms. Polypodium hyperboreum, (hairy alpine |65|polypody) in latitude 68° advances still higher, to beyond Betula nana, (dwarf birch) Draba alpina (mountain whitlowgrass) and Campanula uniflora, (one-flowered bell-flower.) Ihave elsewhere explained myself on the subject of the reasonwhy plants approach nearer to the boundary of eternal snowtowards the North Pole, than they do in the torrid zone. In the kingdom of Quito, M. Bonpland and myself saw moun-tain-ferns reaching into the elevated plain which engirds MountAntisana and along the sides of the Rucupichincha in the val-ley of Verdecuchu, both which spots are 2100 fathoms abovethe level of the sea; and also other herbaceous ferns on MountChimborazo, growing on porphyritic rock, as high up as 2300fathoms. But at heights so great, where the cold is so severe,as well as in parched unshaded plains and spots, the quantity offerns is plainly perceived to diminish from the want of moisture.Their main body is stationed in the temperate and sub-frigidzones, between the elevations of 300 and 1200 fathoms. Tree-ferns in some regions occasionally grow down tothe edge of the sea, and on lowlands in shady spots; butin those parts of tropical America where M. Bonpland andmyself passed five years, they occupy a peculiar zone, in whichthe temperature is between 18 and 22 degrees of the centigradethermometer. A delightful region, where vernal breezesprevail almost the year through, and which lies between theelevations of 400 and 800 fathoms from the level of the sea:though they sometimes descend as low as to the height of 200fathoms. This zone is called by the natives in the Spanish dia-lect, tierra templada de los helechos, the temperate land of theferns. The chief part of the tree-ferns we met with, was inNew Andalusia, near the Convent of Caripa, and in NewGranada near Ibague, Guaduas and Icononzo, and in thevalleys of Peru between Loxa and the river of the Amazonsalso in New Spain near Xalapa. The region of fern-trees isnot far from that of the Cinchonas, or bark-trees; for wefind Cinchona oblongifolia and C. multiflora, however fondthey are of heat, mingling themselves with the tree-fernsin the Andès of Peru, and of the mountains of Quito and New |66|Granada. In New Spain they grow in company with theoaks* of that country; a strange association in the eye of theEuropean.