Thread: Desert plant adaptations

how does a plant survive in dry conditions such as the desert?
i know some such as wide spread roots etc..... But is it also true that their stomata are located inside the plant itself to reduce water loss??

help please.. Thank You

The major adaptation that allows desert plants is CAM (Crassulation acid metabolism).

During the night they open up their stomata and add CO2 to PEP to make oxaloacetate and then store that as malate.

This allows them to keep their stomata closed during the day and not run out of CO2 for photosynthesis.

Otherwise, adaptations against dessication are also very common, like increased water storage, thicker epidermis, and a waxy layer above the epidermis in cacti. The stomata are on the exterior of plants usually on the underside of leaves, even in none desert plants. The exception is aquatic plants like water-lilies that have stomata on the top.

IIRC cactus thorns help protect from sunlight, and collect dew. Apparently for some species defence just happens to be a nice side effect. I wonder which function drove the initial evolution?

First of all, let me tell you that I am not a Botanic expert at all, so my knowledge in this area is very limited. Now back to the topic :

In the southern part of the Desert of Atacama (the driest spot in the world) in Chile, there is a strange and very unusual phenomena that involves almost 200 species of endemic plants, which have adapted to dry conditions by remaining latent in a bulbous or seed state, great part of the year. During Spring time, between September and November in case of any small brief rain, which are very scarce in this area, suddenly the whole area changes, all those seeds and bulbs germinate, bringing the desert to a natural spectacle full of flowers of different colors, which atract insects and small lizards, and the different species complete their life cycle in a very brief moment of time, in which they reproduce and come to a latent state untill the next rain comes by. Whenever, it rains in the zone, it also attracts botanic tourists to the area, since it is very beautiful. This phenomena is called "The flowered Desert ( El Desierto Florido ).

8)

Originally Posted by i_feel_tiredsleepy

The major adaptation that allows desert plants is CAM (Crassulation acid metabolism).

During the night they open up their stomata and add CO2 to PEP to make oxaloacetate and then store that as malate.

This allows them to keep their stomata closed during the day and not run out of CO2 for photosynthesis.

Otherwise, adaptations against dessication are also very common, like increased water storage, thicker epidermis, and a waxy layer above the epidermis in cacti. The stomata are on the exterior of plants usually on the underside of leaves, even in none desert plants. The exception is aquatic plants like water-lilies that have stomata on the top.

Leaves tend to have lower surface area too- fleshier thicker and rounder in cross-section. Less surface area means less evaporation.

thanks for your reply

In the southern part of the Desert of Atacama (the driest spot in the world) in Chile, there is a strange and very unusual phenomena that involves almost 200 species of endemic plants, which have adapted to dry conditions by remaining latent in a bulbous or seed state, great part of the year.

Interesting .. that is a kind of behavior called "drought escaping" .. in the Mohave we have many annual plants that make up a seed bank in the soil and when it rains and it has not in some time we get carpets of annual flowers that grow and reproduce all before the summer arrives. Desert annuals simply are not around much when conditions are dry. They escape drought.

The Mohave desert in the region where I live is not a place where you find lots of cactii .. cactii are drought avoiders. By storing water in their tissues they avoid drought conditions and interestingly if their water supply runs out internaly Cactus have high mortality in the times of drought. So they really can't handle water stress .. they simply avoid it.

Though CAM photosynthesis is found in Cactii .. more common in general is C4 photosynthesis found often in grasses. This type of photosynthesis makes better use of CO2 .. taking more of it in per water molecules lost to the atmosphere. Grasses are found in deserts.

The Creosote Bush .. in the Mohave is an example of a drought endurer .. it stays biologicaly active in even the most dry conditions. It has very small leathery leaves that allow the leaf to stay water tight in dry conditions and it's small size minamizes how much heat energy the leaf absorbs and allows the leaf to cool more easily. Leaf temperature and water efficiency and leaf structure are very important in plants and particular desert plants.

The creosote is able to withstand very low soil water potentials .. that is the "pulling" force of water out of the plant by the very dry soil where as a cactus will wall off it's roots with cork like material to keep itself hydrated but this limits the cactus to it's internal water supply.

Though the creosote stays active in dry periods it's growth is very slow and some small shrubs about seven to fifteen feet or so can be hundreds of years old and some I believe have been dated in thousands of years.

So three adaptations are .. drought escaping .. drought avoiding .. drought enduring. There many other adaptations but these are three basic "behavior" adaptations.

MB ...