29. Describe how the xerophytes are adapted to their habitat - Some have leaves reduced in size / to spine of reduces the surface area for water loss. - Some xerophytes have photosynthetic stems that take the place of leaves; to reduce the surface area for transpiration; - Some shed-off leaves during dry season; reduce surface exposed to transpiration; - Some have thick wax cuticle; which reduces cuticular transpiration; - Some xerophytes have fleshy / succulent /juicy stems / roots for storage of water; - Some have sunken stomata; that accumulate moisture / creating low diffusion gradient; thus reducing transpiration rate; - Most have reduced number of stomata; mostly on the lower leaf surface to reduce the rate of transpiration; The stomata are also small in size to reduce loss of water by transpiration; - Some show reversed stomatal rhythm (open stomata at night and close during the day) to prevent excessive loss of water by transpiration; - Some have succulent stem; that stores water; used in dry season; - Some have long tap roots that extend deep into the soil to absorb water far below. - Some xerophytes have shallow roots that spread widely / extensively in order to trap water from any little shower of rain; - Some xerophytes roll their leaves to reduce surface area exposed thus reducing rate of water loss by transpiration; - Some xerophytes have thorns on their stems / branches / midribs / leaves to protect the plant from predator / browsers / herbivorous animals; - Some xerophytes have a very short life cycle thus grow fast to use the little rain within a very short time; and produce seeds that can survive the drought.
Posted on: Mon, 24 Nov 2014 09:54:42 +0000
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