Indian Journal of Economics and Development, Vol 4 (5), May 2016 ISSN (online): 2320-9836 ISSN (Print): 2320-9828 Weeds: Wealth of the World, not a Waste M. Gopi Department of Plant Biology & Plant Biotechnology, Guru Nanak College, Velacherry, Chennai – 600042, Tamil Nadu, India. lmk_gopi@yahoo.com Abstract Objectives: The main object of this paper is to develop a constructive approach towards weeds and study their geographical distribution. Methods / Statistical Analysis: The weed plants for the present study were random surveyed from in and around Chennai, Tamil Nadu. The weed plants were authentically identified with the help of Floras. The identification was based on floral and leaf characters. Some of the plants are selected for the preparation of extracts to control the larvicidal activity based on the standard basic principles. Findings: A survey on weeds reveals that most of the weeds are of native flora and appear to be uniform distribution throughout state. Application / Improvements :The knowledge of the geographical position and physiography of the state is essential in order to understand the distribution of weeds and their invasion. Keywords: Chemical compounds,Medicinal uses,Mosquitoes repellent,Weeds. 1. Introduction A weed is considered as a great menace to man. But to most of the Botanist, it is a variety and beauty. Whether they occur in the fields or forests, on moors or mountains, by road sides, rivers, canals, pools or ponds, there are the surprises beyond description for those who are willing to stop and stoop to have a look at them and study them with much patience and perseverance. Weeds are generally understood, a group of plants which are very aggressive, competitive and troublesome to man or shortly ‘a plant out of place’. The word ‘weed’ itself is of obscure origin. According to the oxford dictionary the word ‘weed’ has originated from the Anglo-Saxon ‘Woed’. The month of August is referred as ‘Woedmonath’ meaning ‘month of weeds’. Ever since man realized the importance of plants as food, he began to cultivate them in large areas andto him any plant in his / her field other than the planted crop became weed [1][2][3]. It is really sickening to read about the ‘killing’ attitude generated by the newspaper towards the introduced weed Partheniumhysterophorus and the eradication by Government towards Prosopisjuliflora. It is true that it is troublesome, spreading fast, threatening other vegetation causing allergic diseases in man like fever, asthma and eczematic dermatitis, so much so it is classified as one among the seven obnoxious, pernicious and poisonous weeds. In olden days a man died immediately after a bee sting, but no order to eradicate all the bees? Nobody will dare lest one may lose the mouth watering honey! Likewise at the other side of the coin Partheniumhysterophorusis used as a powerful tonic, febrifuge, analgesic in neuralgia, in dysentery etc. [4]. It contains ‘Parthenin’ a bitter Glycoside which is supported to be very active against cancer. It is also free from insect predators, research is being conducted to use it as a pesticide. If it is successful, the costly synthetic insecticides can be replaced away with this compound. The other widespread weed like Prosopisjuliflora contains very essential compound used for antibacterial, antifungal, anticancer, antioxidant and antimicrobial activities [5]. 2. Materials and Methods The weed plants for the present study were random surveyed from in and around Chennai, Tamil Nadu. The weed plants were authentically identified with the help of Floras [6][7][8]. The identification was based on floral and leaf characters. Some of the plants are selected for the preparation of extracts to control the larvicidal activity based on the standard basic principles [9]. 1 www.iseeadyar.org