196 THE TRUE GRASSES. 



culms always die down after the ripening of the seed. 

 When all the culms bear flowers, the rhizomes, whose re- 

 serve material is now exhausted, produce only weak and 

 slender stems for a long time, and only gradually regain 

 the power of producing culms of normal height and 

 thickness. The rhizomes become weakened in a like 

 manner if all or many of the culms of a bamboo clump 

 are cut off. In this case, also, only slender culms are 

 produced for a series of years until their strength is re- 

 stored by the continued activity of the leaves. In green- 

 houses, species which would otherwise form high bushes 

 may be checked in their development and kept small by 

 cutting out many or all of the shorter shoots. In many 

 cases not only the aerial portions die after flowering and 

 ripening of seed, but the rhizomes also, and a renewal of 

 the bamboo forests depends entirely upon seedlings. 

 The preceding will explain why in many species the flow- 

 ers and fruit have not yet been collected and described. 

 In the forests it is not difficult to recognize the different 

 species by the manner of growth, branching, sheaths 

 and leaf-blades of the younger culms, and other charac- 

 teristics ; but without flowers it is only rarely possible 

 to determine the genus. In many species, therefore, a 

 reliable division into genera has not yet been possible.] 



Geographical Distribution. — The Bambusea3 are dis- 

 tributed throughout the tropical zone, but very unevenly ; 

 a few species have penetrated into sub-tropical and even 

 into the temperate zones. The Monsoon region in Asia 

 is rich in species (over one hundred and fifty), but in 

 Africa there are very few (five only known up to this 

 time) ; several occur in Madagascar. America possesses 

 about seventy species, the Pacific Islands a few, and 

 North Australia two ; eleven species grow in Japan, and 

 but one on the Kurile Islands. In the Himalayas they 

 extend to an altitude of 3400 m. above sea level, and 

 still higher in the Andes. Here the species of Ch>isq//< j a 

 form impenetrable thickets, the " Carizales," covering 

 wide areas within the tree limits ; in Ecuador Ghnsquea 

 aristata Munro reaches the snow-line. Many species 



