GEOGRAPHICAL DISTRIBUTION OF PLANTS 



167 



review of the plants belonging to North America ; 

 for so great is the resemblance between the trop- 

 ical productions of the two hemispheres, and so 

 little analogy have they with the productions of 

 other parts of the globe, that it is better to con- 

 template them as a whole, rather than separately 

 to speak of those which grow in the Old and in 

 the New World. Returning therefore towards 

 the polar regions, we shall find, on, comparison, 

 some interesting points of resemblance between 

 the climate and vegetation of tlie corresponding 

 shores of the two continents ; the western coast 

 of America exhibiting appearances similar to 

 those of Norway and other countries on the 

 western shore of Europe ; while the vegetation 

 of Newfoundland, on the eastern coast of Amer- 

 ica, is like that of Kamschatka, on the eastern 

 coast of the Old Continent, in the same lati- 

 tude. In Greenland, of which the southern 

 extremity lies in latitude 59° 38', (ten or eleven 

 degrees nearer to the equator than the point at 

 which trees cease to grow in Norway and Lap- 

 land,) are found only a few bii-ches and willows, 

 of which the utmost height is eighteen or twenty 

 feet. At Nain, on the coast of Labrador, in 

 latitude 57°, only one degree nearer to the pole 

 than Edinburgh or Glasgow, the mean tempera- 

 ture of the year is 5° below the freezing point ; 

 lower, tliex-efore, by 5°, than the mean tempera- 

 ture of Cape North, the extremity of Europe, in 

 latitude 71°. In Canada, which lies under the 

 same parallels of latitude with France, the 

 rigour of the winters is destructive to every spe- 

 cies of tree excepting those belonging to north- 

 ern climates : yet the heat of the summers suf- 

 fices to bring to perfection many of the southern 

 annuals, and such low plants as are protected in 

 winter by the covering of snow. In this country 

 grows the Weymouth pine, not unfrequently 

 planted in our shrubberies. It is a very beauti- 

 ful tree when healthy and vigorous ; and as it 

 grows remarkably tall and straight, affords the 

 best masts for large ships. Anotlier native of 

 Canada is the sugar maple, from whose sap a 

 considerable quantity of sugar is annually pre- 

 pared by the inhabitants. 



The vegetable productions of the temperate 

 regions of North America are distinguished by 

 their variety and splendour, compared with those 

 produced in the same latitudes of the eastern 

 hemisphere. From the territories of the United 

 States we have received some of the most beauti- 

 ful of the family of bog-plants, magnolias, rho- 

 dodendrons, azaleas, and kalmias. The magnolia 

 grandiflora, whose northern limit, according to 

 Humboldt, is in latitude 35i°, has been denom- 

 inated the most admirable production of the 

 vegetable world; it is an evergreen, bearing a 

 leaf not unlike a laurel, but larger, with white 

 flowers five or six inches in diameter, of deli- 

 cious fragrance. From North America comes 



likewise the aloe, distinguished by its long, thick, 

 fleshy leaves, furnished with thorns at the points 

 and along the edges. It blooms only once, the 

 plant dying after it has completed its fructifica- 

 tion, as happens with our annuals and biennials; 

 but, instead of coming to maturity in one or two 

 years, it requires a very long period for its 

 growth : according to the vulgar opinion, a hun- 

 dred years ; but this appears to be an exaggera- 

 tion. When the time for its blooming arrives, 

 a flower-stem rapidly pushes up from the root 

 to the height of thirty feet or more, bearing a 

 branched spike of many thousand large and 

 splendid flowers. From the ridges of the Alle- 

 ghany mountains, which intersect the United 

 States, running nearly parallel with the shore of 

 the Atlantic, comes the beautiful robinia pseudo- 

 acacia, commonly cultivated in our shrubberies, 

 under the name of acacia. Few trees equal it in 

 elegance of foliage, or in the beauty of its pendent 

 clusters of white pea-shaped blossoms, some- 

 times slightly tinged v.'ith pink. It gi'ows very 

 fast, and has been recommended by Cobbett to be 

 planted for timber. In the United States is also 

 found the red cedar, a tree not uncommon in 

 our shrubberies. Its wood is employed foi 

 black-lead pencils, and for lining the inside oi' 

 desks ; for which last purpose it is recommended 

 both by its pleasant smell and by its property 

 of driving away insects. There also grows the 

 tulip tree, the arbutus, and one of the two spe- 

 cies of arbor vitse commonly cultivated here: 

 the other species, of a looser growth, Avhich 

 comes from China, is often improperly called the 

 lignum vitse. The sort of hard and heavy wood 

 known by this name among cabinet-makers, is 

 the produce of the guiacum, a tree gi'owing in 

 the West Indies, of totally different appearance. 



The observations of Mr Barton of Philadelphia 

 on the vegetation of the United States, furnish 

 a remarkable proof how far maritime climates 

 are from being universally milder than inland 

 climates. Comparing the northern limits of the 

 different species of plants on the western and the 

 eastern side of the Alleghany Mountains, he as- 

 certained that this limit extends, in most cases, 

 several degrees further towards the pole in the 

 interior than upon the coast. Thus, on the coast, 

 the growth of the yellow horse chestnut termin- 

 ates at latitude 36°; behind the mountains, at 

 latitude 42°. The black walnut on the coast, 

 ceases to grow in latitude 41°; behind the moun- 

 tains, in latitude 44°. 



It has been observed that in America the form 

 of the continent, and disposition of the moun- 

 tains, admit of a greater intermixture of the 

 productions of warm and cold climates, than in 

 the Old World; where the Mediterranean, ex- 

 tended from east to west, and the mountains, 

 lying in the same direction, form impassable 

 barriers, which preclude the passage of plants 



