Everything about Xerophyte totally explained
A
xerophyte or
xerophytic organism (
xero meaning dry,
phyte meaning plant) is a
plant which is able to survive in an ecosystem with little available water or moisture, usually in environments where potential
evapotranspiration exceeds precipitation for all or part of the growing season. Plants like the
cactus and other succulents are typically found in deserts where low rainfall amounts are the norm, but xerophytes such as the
bromeliads can also be found in moist habitats such as tropical forests, exploiting niches where water supplies are limited or too intermittent for
mesophytic plants. Plants that live under arctic conditions may also have a need for xerophytic adaptations, as water is unavailable for uptake when the ground is frozen. Their leaves are covered with silvery hairs (creates wind break & light reflective surface).
Adaptations of xerophytes include reduced permeability of the
epidermal layer,
stomata and
cuticle to maintain optimal amounts of water in the tissues by reducing transpiration, adaptations of the root system to acquire water from deep underground sources or directly from humid atmospheres (as in
epiphytic orchids), and
succulence, or storage of water in swollen stems, leaves or root tissues. The typical
morphological consequences of these adaptations are collectively called
xeromorphisms.
Importance of water conservation
If the
water potential inside the leaf is higher than outside the leaf, the water vapour will
diffuse out of the leaf down this gradient. This loss of water vapour from the leaves is called
transpiration, and the water vapour diffuses through open
stomata in the leaf. Although this is a normal and important process in all plants, it's vital that plants living in dry conditions have
adaptations that decrease this water potential gradient, and decrease the size of open stomata, in order to reduce water loss from the plant. It is important for a plant living in these conditions to conserve water because without enough water, plant cells lose
turgor and the plant tissue wilts. If the plant loses too much water, it'll pass its
permanent wilting point, where the plant will die.
Types of xerophytic plants are:
- Succulent plants - typically store water in stems or leaves. They include the Cactaceae family which typically have stems that are round and store a lot of water. Often, as in cacti where the leaves are reduced to spines, their leaves are vestigial, or they don't have leaves.
- Bulbs - water is stored in their bulbs, at or below ground level. They may spend a period of dormancy during drought conditions underground, and are therefore known as drought evaders.
- Short-lived annuals can often germinate following rainfall. An example of this is the California poppy whose seeds lie dormant during drought and then, flower and form seeds within four weeks of rainfall.
Further Information
Get more info on 'Xerophyte'.
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