242 PHYSIOGNOMY OF PLANTS. 



painter would be too short for the delineation of all the magnificent 

 Orchidese which adorn the recesses of the deep valleys of the Andes 

 of Peru. 



The Casuarina form, ( 22 ) leafless, like almost all species of Cactus/ 

 consists of trees with branches resembling the stalks of our Equise- 

 tums. 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. Plunder's Equisetum altissimum, 

 ForskaTs 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 (**) (Coniferae). Pines, Thuias, and Cypresses 

 belong to this form, which prevails in northern regions, and is com- 

 paratively rare within the tropics : in Darnmara 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 Orchidese 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 Aroidese 

 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, Dracontiuin, Caladium, and 

 Arum, all belong to this form, which prevails chiefly in the tropical 

 world. On the Spanish and Italian 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 Pothos and Arum 

 are representatives, I place a form with which, in the hottest parts 



