Question

List four structures or mechanisms, as discussed in the last lecture, that plants have developed to adapt to an environmental stresses. 5 pts. 2 4 Explain the purpose of one of them:

Answer 1

Answer :- Plant have developed many structure to adapt in a stressful environmental conditions.
Halophyte and Xerophyte plant develop different kind of structure and mechanism for surviving against stressful environmental conditions. These structures are follows -
1.Pneumatophore root.
2.Stilt root.
3.Viviparous germination.
4. Succulent leaves and spine.
5.Waxy Cuticle in leaves.
Pneumatophore root :- Pneumatophores are the aerial roots that grow vertically upwards(negative geotropism) and exposed to the air.These kind of root specially found in halophytic plant among them mostly in mangrove plants. Mangrove plants are mostly grow up in saline environment nearly coastal areas.During tide plants are constantly submerged under water. So the plant does not acquire enough oxygen through their root that was uprooted.There is high concentration of salts like sodium chloride, MgSO4 etc. Due to high concentration of salt they developed pneumatophore root for acquiring enough oxygen from the upper surface of mud that means from open air. They have small openings (lenticels) in their bark so that air can reach the rest of the plants root system.So the pneumatophore facilitate aerial respiration for halophytic plant that's why these kind plant grow in the salty environment otherwise they died due to low oxygen level.

Function of stilt root :- Stilt roots are the adventitious roots that help in supporting the plant body. Also known as support roots. Another important ability of stilt roots is to allow the exchange of gas in oxygen-poor sediments. Stilt root are commonly found in mangrove plant because mangrove trees are found in shallowly flooded high tide region. Everytime they have chance to be uprooted. These kind of roots prevent uprooting of this plant in narrowly attached soil component of high tide zone.
Viviparous germination :- In viviparous germination the seeds get germinated being attached to the parent plant. The embryo grows out of the seed and then out of the fruit and projects out as a seedling with roots and hypocotyl. These kind of germination mainly found in halophytic plan that grow in dense thickets or forests along tidal estuaries, in salt marshes, and on muddy coasts. In this area soil concentration is higher. Due to high soil concentration the seed can't germinate in this type of soil also due to tide.For this these plant develope this kind of germination for their seed germination.
Function of Spine:- Spine helps the plant low transpiration of water. In xerophyte plant water are quickly evaporate due to transpiration.For avoiding water loss leafs are transformed to spine because Due to high sunlight water evaporates quickly in desert region. So spine helps these plant to water loss and succulent leaves also helps in saving the water.