^34 



ZONES AND REGIONS 



[Pt. Ill, Sect. I 



also frequently found wild. The largest forms grow in forests scattered 

 among other trees, or they constitute independent forests (Fig. 207) ; 

 smaller forms are common as underwood. 



Very unique and occasionally very common forms of the megathermic 

 flora are the species of Pandanus (Figs. 115, 116, 122, 212, 214), which 

 however rarely occur in great numbers together. They are confined 

 to the Old World. They occur chiefly by the seaside, but also in forests ; 

 only rarely do they form pure woods. 



The Araceae, owing to their occurrence in great numbers and to the great 



diversity in their species, take 

 a prominent place in tropical 

 forest scenes. Among them are 

 found lianes like species of 

 Philodendron, Monstera, Pothos ; 

 epiphytes like species of An- 

 thurium and Philodendron, and 

 many terrestrial herbs which are 

 often social. To the aroids 

 belong some of the most remark- 

 able productions of the tropics, 

 for example the gigantic Amor- 

 phophallus Titanum in Sumatra. 

 Araceae are also important con- 

 stituents of the swamp-flora, as 

 the species of Colocasia and 

 Alocasia. 



The Scitamineae, in the form 

 of perennial herbs as tall as a 

 man, are common and prominent 

 constituents of the forest flora. 

 Bananas, Musa paradisiaca and 

 M. sapientum (Fig. 49), are not 

 only among the commonest and most conspicuous cultivated plants, but 

 also, in Asia, are frequent in the forest. Heliconieae are in particular 

 characteristic of the tropical forests of America, as various Zingiberaceae 

 are of those of Asia. Madagascar possesses the only tree-form of the order 

 in the traveller's tree, Ravenala madagascariensis, which is grown in all 

 tropical cultivated lands as an ornamental tree (Fig. 123). 



Finally, amongst prominent monocotyledonous families forming con- 

 stituents of the flora, mention should be made of the OrcJiidaccae, which, 

 in particular, as epiphytes, develop an astonishing diversity of forms, and 

 also of the Bromeliaceac in tropical America, which are likewise chiefly 

 epiphytic. The grasslike Eriocaulaceae are, especially in species of the 



Fig. 122. Pandanus sp. Botanic garden at Bniten- 

 zorg. From a photograph by G. Karsten. 



