Anatomical Adaptations of Xerophytes: a. Most of them produce root buttresses for the support of their huge trunks. B Succulents with fleshy leaves or Malacopyllous xerophytes: Malacophyllous xerophytes are characterized by reduced stem and succulent leaves. Reproductive characters Classification of plants based on water relation Warming, 1990 1. The function of leaves is also taken up by the stem thus greatly reducing total transpiring area. The waxy cuticle prevents extreme water loss from the water stored inside the stem, helping keep the plant alive by preserving the internal water reservoir. Mesophytes can be classified into two main community groups: 1 Communities of grasses and herbs.
Ephemerals: They are short-lived annual plants of arid zones which complete their life-cycle within a very small period when sufficient moisture is available. Floating hydrophytes: Ø These plants float freely on the surface of the water. Hypodermis Iiypodermal layers of xerophytes are thick and well developed. They respire by gills which are specialized breathing organs to use gases solved in water. Unlike hydrophytes, it is common for mesophytes to have substantially developed stem and xylem.
The physiology of aquatic plants is greatly affected by the change in osmotic concentration of water. In these plants, leaves are greatly reduced, so the main function of leaves, the photosynthesis, is taken up by these green phylloclades or cladodes which are modified stems. Body shape is stream-lined, neck constric ion disappears and tail enlarges e. In this way plants are subjected to little mechanical stress and strain of water. Members of families Gramineae, Ranunculaceae, Papilionatae and Compositae are found in abundance.
Seeds may be modified to require an excessive amount of water before germinating, so as to ensure a sufficient water supply for the seedling's survival. Materials and methods Materials:- Xerophytes root, stem. The neck becomes short and immobile. The free-floating, on-vascular hydrophytes constitute phytoplanktons. Limbs become fleshy and -like expansions or paddles for swimming.
These plants are in contact with both water and air. Physiological adaptations in hydrophytes : The aquatic plants exhibit a low compensation point and low osmotic concentration of cell sap. According to Iljin 1957 , the protoplasm in these plants is less viscous and more permeable. The ears may function as efficient radiators to the cooler desert sky, which on clear days may have a radiation temperature of 25C below that of the animal. If the plant does have small leaves they will have a very thick waxy cuticle to prevent the evaporation of water, as living in a hot environment means water will evaporate at a faster rate.
Ø The osmotic concentration is equal or slightly higher to that of surrounding water. There is not much of difference in the photosynthesizing peripheral cells and the cells of the water storage tissue except that the latter do not possess chloroplasts and their cell walls are made up of cellulose. Sometimes they may be reduced to spines, as for example, in Ulex, Opuntia, Euphorbia splendens Fig. Many of these trees are more or less evergreen and their leaves show xeromorphic modifications, which enable them to survive during the period of drought. Some amphibians like spade- foot toads Scaphiopus an estimate for eight or nine months in an underground cell lined with a gelatinous substance that reduces evaporative losses through the skin. Xerophytes: Plants adapted to survive under the condition of very poor supply of available water in the habitats. In other words, mesophytes are the plants of those regions where climates and soils are favourable.
Mere also the functions of the leaves are performed by the stem which shows combined characters of a xerophytic stem and a leaf. Leaf loss will be activated in more severe stress conditions. Although they have adaptations to live in stressful weather and conditions, these plants thrive when well-watered and in tropical temperatures. The roots also have large capacity which allows them to hold large amounts of water, as when it does rain the plant will want to absorb as much water as possible in order to keep water balance within the plant as water is needed to keep the calls turgid and to carry out photosynthesis and get minerals into the plant. They can survive in these areas because they possess adaptations that keep them from drying out.
Large desert animals such as the camel can use water effectively for evaporative cooling through the skin and respiratory system because their low surface-area-to-bouy-size ratio and lower internal heat production result in slower accumulation of heat. It can be found at lower latitudes at high elevations as well. Anatomical Adaptations of Hydrophytes Ø Anatomically the hydrophytes shows the following characteristics and their anatomical adaptations ensure these features: A. Ø Absorption of water and minerals takes place through the cell surface. Adaptations to conditions Humans Humans living in the Arctic region generally rely on warm clothing and buildings to protect them from the elements.
The leaves are oriented horizontally without any waxy coating or hairs. This means that guard cells on the stomata are generally inactive. These shrubs have the additional property of being palatable to grazing animals such as sheep and camels. Ecological Adaptations in Xerocoles Desert Animals : Like plants, desert animal are also adapted to conserve moisture and escape heat of shimmering sun. These groups are as follows: 1. There is no evidence that fat is grown in response to cold, although its presence is advantageous.
Young bees emerge from underground cells at the very time when the particular flowers on which they feed are in flower. Insects and myriapods have a particularly well- developed covering over the respiratory surface as well as a tracheal system Vertebrates have stratified skin with several cellular layers in addition to a well-protected respiratory surface. For the retention of body heat and for the reduction of specific gravity of beady, a thick fatty layer called blubber is formed below skin. The succulent are said to resist, rather than endure, drought. Phloem parenchyma is extensively developed. An evolutionary strategy employed by desert xerophytes is to reduce the rate of seed germination.