64 GEOGRAPHICAL DISTRIBUTION 
found in both hemispheres, and Chusguea, upwards of 30 species, 
all restricted to America, and ascending on the Andes as high as 
Arundinaria does on the Himalayas. In the whole extent of 
North America north of Mexico there is only one species of uncul- 
tivated bamboo, Arundinaria macrosperma; in Europe there is 
not one native species, while on the continent of Africa there are 
only one or two native flowering species known. 
Confining our attention now to the distribution of British grasses, 
many species occur in the southern and south-eastern parts of 
England that have not been observed further north. Most of 
these, as Polyfogon monspeliensis and P. littoralis, Agrostis setacea, 
Phleum phalaroides, Gastridium lendigerum, Corynephorus can- 
escens, Cynodon dactylon,* Bromus madritensts, *Festuca uniglumis 
and */. myurus,*Briza minor, Poa bulbosaand Brachypodium pin- 
natunt, are common all round the Mediterranean, extend up the 
west coast of Europe to the English Channel, some reaching 
Scandinavia. Those marked * occur locally or sparingly in 
Ireland. Lagurus ovatus, Cynosurus echinatus, and Bromus maxt- 
mus do not get further than the Channel Islands, except as intro- 
duced casuals, and are not indigenous to Britain proper. The 
last-named is naturalized on the Tyne ballast-hills, its northern- 
most station. Cynodon dactylon is common in all warm regions, 
and in India is one of the most valuable pasture grasses. A few 
species occur in the Scotch Highlands that are not found else- 
where in Britain, viz. Alopecurus alpinus, Phleum alpinum, Poa 
laxa, P. stricta, and Deschampsia alpina; not by reason of the 
somewhat higher latitude, but because of the elevation of the 
mountains there, as these species occur in more southerly latitudes 
on the continent of Europe, on the Alps and Pyrenees. The grasses 
found at the highest elevations in North Britain are : above 4,000 ft., 
Deschampsia alpina and Festuca ovina, the latter occupying the 
highest summits in abundance ; from 3,000 to 4,000 ft., Deschampsia 
flexuosa, Anthoxanthum odoratum, Nardus stricta, Poa alpina; 
also Poa annua about the springs and rills ; from 2,000 to 3,000 ft., 
Alopecurus alpinus, Avena pratensis, Festuca duriuscula, Phleum 
alpinum, Sesleria caerulea. Huierochloe borealis, whose only 
British locality is the extreme north of Scotland, is abundant in 
Iceland, Northern and Arctic Europe, Siberia and Arctic America. 
One species is confined to the eastern side of Britain, namely 
Ammophita baltica, on the coast of Northumberland, while another 
species, JZzbora verna, occurs only on the Isle of Anglesea. The 
former extends all round the shores of the Baltic from Gothland to 
Holland, the latter is found throughout Western Europe, including 
the Channel Islands, and in North Africa. MMelica nutans, distri- 
buted over Arctic Europe and Northern Asia, is restricted in Britain 
to the western counties, but is not recorded from Ireland. Several 
species are dependent upon the cultivation of the soil for their 
occurrence and perpetuation in our country; they are usually in- 
troduced with grass and clover seeds. Such are Panicum Crus- 
galli, P. glabrum (Digitaria humifusa), P. sanguinale, Setaria 
