Geographical Distribution of Plants. 250 



and that every inhabitant of the stove and green-house ought to be tried in 

 the open air, 



" There appears something enigmatical in the causes which aiFect the 

 growth of many exotic shrubs well known in gardens and plantations ; for 

 many natives of the north of Asia, Portugal, Japan, and even of South 

 America, resist the severity of our winters much better than many which 

 are indigenous in Italy, the South of France, and Germany. The strongest 

 instances are those of the common myrtle, pomegranate, and oleander, all 

 of which, though European plants, perish at a temperature no way injurious 

 to the jBhododendron ponticum of Asia Minor. This, as well as the Rho- 

 dodendron maximum of North America, is much more hardy than the bay, 

 or even than the Portugal laurel ; though it is probable the Pontic rose-bay 

 may be a native of the lower ridge of Caucasus, and the American species 

 generally grows in subalpine situations. From Pursh we learn, that /Rho- 

 dodendron maximum var. 1. roseum, which is the variety common in our 

 gardens, is found near rivulets and lakes, in the mountains from Canada to 

 Carolina j var. 2. album, in the shady cedar-swamps of New Jersey and 

 Delaware; var, 5. purpureum, near lakes on the highest mountains of 

 Virginia and Carolina. The author of the Flora of North America is in- 

 clined to think these three distinct species. i?hododendron punctatum is 

 also from the mountains of Carolina, at the head of the Savannah river, 

 and jRhododendron catawbiense is a native of the high mountains of Vir- 

 ginia and Carolina, at the head of the Catawba river. The Lapland, the 

 Kamtschatkan, the two Swiss, and two Siberian rose-bays, are also alpine 

 plants, and the same may be said of the rare species found on the mountains 

 of Ceylon. This may, in some measure, account for these elegant shrubs 

 withstanding our severe and changeable winters, though they will not thrive 

 in the fenny parts of Lincoln or Cambridgeshire, or in Holland. 



" On the. coasts of Greece, Albania, and Dalmatia, I have observed the 

 limestone rocks covered with the mastic (Pistacia ientiscus), myrtle, rose- 

 mary, laurustinus, common arbutus, and juniper. Of these, the first and 

 second will not survive our winters; the third, fourth, and fifth will not 

 perfect their fruit except in favourable situations, and when the season 

 proves uncommonly mild ; but the last ascends our mountains to the height 

 of 1500 feet. 



" In gardens and well-sheltered grounds, the common laurel of the 

 Levant (Prunus Lauroc^rasus) and Portugal laurel (Prunus lusitanica) 

 flower freely ; and, provided the season be mild, ripen their fruit. The 

 Chinese rose (Posa semperflorens) and the cluster-flowered quince of Ja- 

 pan (Cydonia speciosa), when protected by a wall, flower throughout open 

 winters; and the latter has perfected its fruit at Wallington, and in similar 

 situations. Posa multiflora of China, Buddlea globosa of Chile, Aucuba]ar 

 ponica. Camellia japonica, and Corchorus japonicus, survive our severest 

 seasons, and thrive very well ; but the bay of Italy (iaurus nobilis) flowers 

 only in the southernmost parts of Durham, and the sheltered vales of 

 Cumberland. 



" On the other hand, the Provence rose (Posa centifolia) and the offici- 

 nal rose (Posa gallica), said to be from the south of France, but, most pro- 

 bably, originally from Asia Minor, and the damask rose (Posa damascena), 

 from the same country, are to be met with in every garden ; nor is the musk 

 rose (Posa moschata) of the north of Africa very scarce. The roses of Si- 

 beria, the Alps, and North America, thrive very well, as does the evergreen 

 rose (Posa sempervirens) of Italy and Germany, a plant confounded, by 

 foreign botanists and British gardeners, with the white trailing dog rose 

 (Posa arvensis). The double yellow rose of the Levant (Posa sulphurea) 

 never flowers in the vicinity of Newcastle; and the same maybe said of the 

 single yellow rose (Posa liitea) of the south of Europe, though it flourishes 

 in the neighbourhood of Hexham, 20 miles to the west, at Norton, in the 



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