Tuesday, March 11, 2008
Seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. There are many parts in a seed viz. seed coat,radicle , plemule ,endosperm and embryo( form of the three-cotyledon,epicotyl and hypocotyl).The formation of the seed completes the process of reproduction in seed plants (started with the development of flowers and pollination), with the embryo developed from the zygote and the seed coat from the integuments of the ovule.Seeds have been an important development in the reproduction and spread of flowering plants.
Monday, March 10, 2008
The portion of the germinating seed which grows and descend deep into the soil is called ROOT.They usually originate from the emerging radicle of a germinating seed but ADVENTITIOUS ROOTS originate from the other parts of plant like stem and leaf.They are of two types viz. Tap root system and Adventitious root system.
Tap root system:
The root system consisting of the main primary root and secondary roots.eg-pea,mustard,mango.
Adventitious root system:
The root system where radicle does not develop and replaced by a number of minute thread like roots arising from EPICOTYL.eg-Fibrous root-grass , Cauline root-Banyan and Foliar root-Bignonia.
Know about PLANTS !!!
Plants are a major group of life.They can be classified in three types on the basis of stem-viz.herbs , shrubs and trees. About 350,000 species of plants are found yet in the whole world. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 15,000 are bryophytes.The plants produce GLUCOSE and nutrients by a process called Photosynthesis.They are AUTOTROPHS because they prepare their own food.