LEADING GENERA 63 
regions, northern or southern, both of the old and new worlds, are: 
Trisetum, 50 species ; Glyceria, 30 species ; Agropyrum, 20 species; 
Triodia, 20 species (very few extending into the tropics in America 
or Africa) ; Deschampsta, 20 species (also sparingly represented in 
mountain regions within the tropics) ; Avena, 40 species, mostly 
in the temperate regions of the old world, with a few in extra- 
tropical North and South America, one or two of the annuals 
widely dispersed as cornfield weeds. Distributed over the tem- 
perate regions of the northern hemisphere are : Bromus, 40 species, 
with a very few tropical or southern ; and JZe/zca, 30 species, some 
extending down the Andes into extra-tropical South America and 
some occurring in South Africa. 
The 32 genera above mentioned comprise about 2,000 species, 
nearly two-thirds of the total number; the remaining 1,200 are 
grouped into about 266 genera, many of which are monotypic, ze. 
having but one species. 100 genera are common to both the old 
and new worlds, and upwards of 50 are common to the extra-tropical 
regions of both the northern and southern hemispheres. More 
than 50 genera are endemic in America ; of these, 20 belong to the 
Mexicano-Texan region, a few of them extending into California 
and several down the Andes of South America as far as Bolivia ; 
other 20 are tropical or sub-tropical, including a few Brazilian 
monotypic ‘ones, while about ten genera are restricted to North 
America. Gray’s Manual of the Northern United States describes 
66 genera, of which no less than 35 are also British. For Europe, 
Nyman’s Conspectus enumerates 116 genera, which include the 
48 British. Less than 20 genera are endemic in Europe, and 
about a dozen (nearly all monotypic) are confined to the Medi- 
terranean region. Many of the European genera range over the 
whole world, but are of course most abundant in the northern 
hemisphere. Harvey’s South African genera are 89, of which 26 
are represented also in Britain. Of the 90 Australian genera, 54 
are found in both the old and new worlds, half of them being chietly 
tropical ; 18 other genera belong to the Indo-Australian region 
(ranging from Australia over the Malay Archipelago into South- 
Eastern Asia); 3 genera are common to Australia and New 
Zealand, and 1 occurs also in South Africa ; only 14 genera are 
endemic in Australia, noted for its peculiar fauna and flora—a 
remarkable illustration of the wide diffusion of this family. Out 
of 30 genera indigenous to New Zealand, no less than 17 are found 
also in Britain. 
The distribution of the Bambusee is peculiar; this tribe com- 
prises 22 genera, of which 16 occur in India, China, Japan, the 
Malay Archipelago, Polynesia, Africa, Madagascar, and include 
the 8 genera of berry-bearing bamboos (with a thick fleshy peri- 
carp) confined to the East. 6 genera, comprising 70 species, 
are confined to tropical America. Only 2 genera are common to 
both eastern and western hemispheres. The large genera are 
Bambusa, 24 species, confined to Africa and the East with the 
sole exception of B. vulgaris; Arundinaria, about 24 species, 
