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Show 362 PHYSIOGNOMY OF PLANTS. organs determine the peculiar character of the effects produced, the outlines of light and shade. "Phyllodias," says Kunth, "can, according to my view, only occur in families which have compound pinnated leaves j and in point of fact they have as yet only been found in Leguminosre (in Acacias). In Eucalyptus, Metrosideros, and Melaleuca, the leaves are simple (simplicia), and their edgewise position arises from a half turn or twist of the leaf-stalk (petiolus) j it should be remarked at the same time that the two surfaces of the leaves are similar." In the comparatively shadeless forests of New Holland, the optical effects here alluded to are the more frequent, as two groups of Myrtacere and Leguminosre, species of Eucalyptus and of Acacia, constitute· almost the half of all the grayish-green trees of which those forests consist. In addition to this, in Melaleuca there are formed between the layers of the inner bark easily detached portions of epidermis which press outwards, and by their whiteness remind the European of our birch bark. The distribution of Myrtacere is very different in the two continents. In the New Continent, and especially in its western portion, it scarcely extends beyond the 26th parallel of north latitude, according to .Joseph Hooker (Flora Antarctica, p. 12) j while, in the Southern Hemisphere, according to Claude Gay, there are in Chili 10 species of Myrtus and 22 species of Eugenia, which, intermixed with Proteacere (Em bothrium and Lomatia), and with Fagus obliqua, form forests. The Myrtacere become more abundant beyond 38° S. lat.-in the Island of Chiloe, where a Metrosideros-like species of Myrtus (Myrtus stipularis) forms almost impenetrable thickets under the name of Tepuales j in Patagonia j and in Fuegia, to its extremity in 56!0 S. lat. In the Old Continent, they prevail in Europe as far as the 46th parallel of north latitude j in Australia, Tasmania, New Zealand, and the Auckland Islands, they advance to 50!0 south latitude. (B2) p. 244.-" Melastomacer£." This group comprises the genera Melastoma (Fothergilla and Tococa Aubl.) and Rhexia (Meriana and Osbeckia), of which we found, on either side of the Equator in tropical America alone, 60 new species. Bonpland has published a superb work on Melastomacere, in |
