

GRASSES. 



296 



No. of Species. 



Proportion of the Species to 

 the whole of the Grasses. 



Tor. Zone. 



Panicese - - 

 Stipacese - - 

 Agrostideee - 

 Bromeas - - - 

 Chlorideae - - 

 Hordeaceas - 

 Saccharineae 

 Oryzese - - - 

 Olyreae - - - 

 Bambusaceee 



303 

 40 

 58 



133 

 78 

 33 



120 



10 



18 



6 



Temp. Zone. Tor. Zone 



103 



58 



220 



554 



30 



101 



65 



9 



4 



3 



23 



1 



32 

 •I 



1 



T3" 1 ? 



Temp. Zone. 



2ff 



i 

 I 



S 

 i 



T53 



1 



355 



1 



"Hence it follows that not one of these groups belongs exclusively to eithei 

 the one or the other zone, but that, on account of the proportionally greater num- 

 ber, the Panicese, Chlorideae, Saccharinse, Oryzeae, Olyreas, and Bambusaceee, may 

 be regarded as tropical, and Agrostideae, Bromeas, and Hordeaceae, as extra-tro- 

 pical forms ; and that there is, consequently, a considerable contrast between 

 the former of these two zones. On the contrary, the difference between the 

 various continents and degrees of longitude is inconsiderable. Neither in the 

 torrid nor temperate zones has any group in the continent a perceptible prepon- 

 derance over another. The result also appears to be the same, on comparing 

 the two hemispheres : we know, however, too little of the southern to state 

 this precisely. In respect of elevation, the distribution, according to the degrees 

 of latitude, is very similar ; for, in the mountains of South America, the pro- 

 portions of the larger groups are : 



" Between the genera the contrast is naturally greater, and manifests itself 

 not only according to latitude, but also longitude. Thus, in the torrid zone, the 

 genus Paspalus has a decided preponderance in the New World. Moat of the 

 genera, however, especially the larger, for example, Panicum, Andropogon, 



