Monday, February 29, 2016
EXCRETION IN PLANTS -PART 2-TEXT
EXCRETION IN PLANTS -PART-2
Alkaloids, Tannins, Resins, Gums, Latex etc., are some of the secondary metabolites in plants.
These are nitrogenous by products and poisonous. These are stored in different parts of the plant. Some of the alkaloids are used in medicines. Common alkaloids, the plant and the part in which they occur are give below……..
Tanninsare carbon compounds. These are stored in different parts of a plant of a plant and are deep brown in colour. Tannins are used in tanning of leather and in medicines e.g. cassia, acacia.
Occur mostly in gymnosperms in passages called resin passages. These are used in varnishes-e.g pinus.
Plants like Neem, Acacia secrete a sticky substance called gum when branches are cut. The gums swell absorbing water and help in the healing of cut parts of a plant. Economically, gums are valuable being used as adhesive and binding agents, in the preparation of medicines, foods etc.
Latex is the milky white substance by plants belonging to Euphorbiaceae, Apocyanaceae. Asclepiadaceae and papvaraceae. Latex is stored in latex cells or latex vessels. From the latex of Hevea braziliensis (rubber plant) rubber is prepared.
Nitrogenous substances are also found in the walls of pollen grains. These are protein substances and when they enter our body, they cause allergy. Hence, they are called allergins. They cause skin allergy(urticaria) asthma etc.
Aromatic oils and scents occur in the leaves of lemon grass, ocimum, eucalyptus etc.