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Show 242 PHYSIOGNOMY OF PLANTS. painter would be too short for the delineation of all the magnificent Orchidem which adorn the recesses of the deep valleys of the Andes of Peru. The Casuarina form, (29) leafless, like almost all species of Cactus, consists of trees with branches resembling the stalks of our Equise· turns. It is found only in the islands of the Pacific and in India, but traces of the same singular rather than beautiful type are seen in other parts of the world. Plumier's Equisetum altissimum, Forskal's Ephedra aphylla from the north of Africa, the Peruvian Colletias, and the Siberian Calligonum pallasia, are nearly allied to the Casuarina form. As the Banana form shows the greatest expansion, so the greatest contraction of the leaf-vessels is shown in Casuarinas, and in the form of Needle trees (28) (Coniferm). Pines, Thuias, and Cypresses belong to this form, which prevails in northern regions, and is comparatively rare within the tropics : in Dammara and Salisburia the leaves, though they may still be termed needle-shaped, are broader. In the colder latitudes, the never-failing verdure of this form of trees cheers the desolate winter landscape, and tells to the inhabitants of those regions that when snow and ice cover the ground the inward ( life of plants, like the Promethean fire, is never extinct upon our planet. Like mosses and lichens in our latitudes, and like Orchidere in the tropical zone, plants of the Pothos form (24) clothe parasitically the trunks of aged and decaying forest trees: succulent, herbaceous stalks support large leaves, sometimes sagittate, sometimes either digitate or elongate, but always with thick veins. The flowers of the Aroidere are cased in hooded spathes or sheaths, and in some of them when they expand a sensible increase of vital heat is perceived. Stemless, they put forth aerial roots. Pothos, Dracontium, Caladium, and Arum, all belong to this form, which prevails chiefly in the tropical world. On the Spanish and Italia-n shores of the Mediterranean, Arums combine with the succulent Tussilago, the Acanthus, and Thistles, which are almost arborescent, to indicate the increasing luxuriance of southern vegetation. Next to the last-mentioned form, of which the Pathos and Arum are representatives, I place a form with which, in the hottest parts |