CHAP, xcii DECIDUOUS DICOTYLOUS FOREST 337 



summer-monsoon in southern Asia. According to Brandis,^ on the west 

 coast of cis-Gangetic India up to a certain altitude forests are deciduous ; 

 at a greater altitude, where atmospheric precipitations in winter are more 

 abundant, monsoon-forest is replaced by rain-forest.^ 



The trees in monsoon-forest are tall. In addition to the important 

 teak-trees, there are species of Sterculia and Erythrina, Grewia elastica, 

 Milletia Brandisiana, and others. Underwood is scantily represented, but 

 large bamboos play a considerable part. Epiphytes are not numerous. 



Monsoon-forest is represented on the Misantla plateau in Mexico, and 

 has been described by Karsten.^ This forest consists mainly of deciduous 

 plane-trees. Cecropia and Croton also occur. Underwood is formed by 

 Anonaceae and Urticaceae ; while clumps of Heliconia are scattered here 

 and there. Lianes and epiphytes are scanty in comparison with their 

 abundance in rain-forest. The hanes are largely species of Vitis and 

 Menispermaceae. Among epiphytes species of Philodendron are common. 

 The forests that Schweinfurth mentions as occurring on the western 

 slopes in Abyssinia may be monsoon-forests. 



CHAPTER XCIII. EVERGREEN DICOTYLOUS FOREST 



Evergreen dicotylous forests occur not only in rainy tropical and 

 subtropical regions, but also in the cold-temperate zone of the Southern 

 Hemisphere. Though it is true that in many of these forests species occur 

 which are entirely leafless for a shorter or longer period, yet most of the 

 trees retain their foliage until after a new crop of leaves has appeared, 

 or for more than twelve months. 



In most regions dry periods can step in at any season of the year, 

 and in the region of tropical rain-forest, for instance in Java, the day 

 itself may show dry periods (in the morning until rain falls at 2 or 3 o'clock 

 in the afternoon) during which the air is relatively dry, and transpira- 

 tion may become a source of danger.* Consequently nearly all leaves of 

 trees composing the high-forest are protected in some way from excessive 

 transpiration. 



The leaf, not only for this reason but also because it lives for more 

 than a year, by no means displays such uniformity of structure as in 

 deciduous dicotylous forests of temperate countries. 



In evergreen, tropical dicotylous forest defoliation and foliation are 



. .neither so general, nor so synchronous in the different species, as in 



Itemperate regions ; so that there is no such seasonal change in leaf tint. 



As the foliage ages it is gradually shed ; yet this process is especially 



active in certain months, for instance, in July to September in central 



J Brazil.^ Throughout the year the tint of the forest is of a darker green 



3 than that of our European forests ; although certain species show striking 



(1: colours when they are leafing (the young leaves often being red), their 



(I effect is lost in the general mass of foliage of the other species. Bud-scales 



ire usually wanting. 



As the green leaves presumably are active throughout the year (indeed 

 Borne species produce new foliage all through the year) it is easy to see 



" Brandis, 1898. * See S. Kurz, 1875; Biisgen, Jensen, und Busse, 1905. 



^ Karsten, 19036. * Habcrlandt, 1892. ' Warming, 1892. 



WARMING Z 



