11] HYDROPHYTES AND MESOPHYTES 37 
property largely taken advantage of in certain forest 
operations. 
Other grasses, particularly annual species, show their 
adaptation to xerophytic habits by forming bulbous store- 
houses at the base of the culms—e.g. Phlewm arenarium. 
Some Graminaceze are hydrophytes, such as Arwndo, 
Glyceria, &c., with large intercellular spaces in their tissues; 
while many species—e.g. Aira cwespitosa, Agrostis canina, 
Molinia cerulea—grow on wet moor-lands, forming peren- 
nial tufts, with or without creeping rhizomes. 
The mesophyte grasses are especially characteristic of 
what may be termed carpets—a lawn is a good example 
on a small scale, though of course we must remember 
that here the struggle for existence has been artificially 
interfered with more or less. Such carpets consist of the 
densely interwoven rootlets and rhizomes forming sod, and 
contain much humus from the accumulated débris of former 
years. These grass-carpets may be composed of nearly 
pure growths of a few species, or of very many different 
grasses and other herbage. They are common in Arctic 
regions, on Alps, and in temperate climates generally, where 
we know them as meadows, hay-fields, pasture and lawns. 
The Bamboos in the wider sense have a physiognomy 
of their own, e.g. in India, and may drive out most other 
plants and form dense undergrowths or jungle of interlaced 
stems and leaves and thorny shoots. Similar growths 
occur on the Andes and elsewhere in South America. In 
some parts of India and tropical Asia the taller bamboos 
form aggregates comparable to dense forests, and such 
forests are common on the banks of several large tropical 
