Many cacti and
succulents grow in high plain and
quite a few come from high altitude or almost alpine
environments. Various altitude
growing succulents are difficult or impossible to acclimatize in warm
plain habitat or in subtropical
marine environment (and in heated greenhouses too), but many of them can
live more or less well in temperate climate. As one moves from low
elevation to high altitude the environment changes from tropical (or
perhaps temperate depending on which mountain you consider) to arctic.
The gradient of latitude that alters the temperature and season length
variables is mirrored in altitude. So the same gradient of
organisms that exists from equator
to poles is expected to be reflected from base to mountain top.
The habitats
at high altitude
include montane, subalpine, and alpine; the montane one are
generally defined as being in areas above 1,000 m.
The change of altitude lead to a vast variety of physical and chemical
modification like:
Wet or
dry conditions due to clouds
and complex topography,
Difference in exposure
due to slope and steepness. etc...
Any combination of
environmental factors contribute to create unique
ecological niches to which
certain plant have become
adapted, besides this
habitats are often separated one from each other by warmer,
lower elevation
regions, this is the cause of the
evolution of numerous
endemic species.
Many
plants from high altitude have
developed special habits and are
covered by hairs or
waxy coating to protect against the
intense solar radiation.
Some species of climbing
plants develop holdfast roots which help to support the vines on
trees, walls, and rocks. By forcing their way into minute pores and
crevices, they hold the plant firmly in place.
Climbing plants, like the poison ivy (Toxicodendron
radicans), Boston ivy (Parthenocissus
tricuspidata), and trumpet creeper (Campsis
radicans), develop holdfast roots which help to
support the vines on trees, walls, and rocks. By forcing their
way into minute pores and crevices, they hold the plant firmly
in place. Usually the Holdfast roots die at the end of the first
season, but in some species they are perennial. In the tropics
some of the large climbing plants have hold-fast roots by which
they attach themselves, and long, cord-like roots that extend
downward through the air and may lengthen and branch for several
years until they strike the soil and become absorbent roots.
Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House,
1994