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.

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Abstract

Background/Objectives: Most of the species of Datura imposes a wide lacuna in our knowledge especially for proper identification and pharmacognostical studies. Anatomical structure is most likely to provide evidence concerning the interrelationships of families or in establishing the real affinities of species of uncertain taxonomic status.

Methods/Statistical Analysis: The wood anatomical characters and certain ‘anomalous’ or uncommon structures of the axis have been extensively employed by the systematic anatomists for drawing conclusion with reference to systematic position and phylogeny of plant taxa. Apart from anatomical and trichome studies, palynological investigation is also to be attempted. This will give additional information both for diagnosis of the plants and for conformation their taxonomic position.

Findings: In Datura species epidermal trichomes have been cited as one of the criteria for distinguishing the species. The cross sectional outline of young stem differs significantly in the species studied. The cross section shape is circular and densely pubescent in Datura innoxia, angular in Datura fastuosa. The secondary xylems of ischolar_mains are uniformly dense with wide cylinder of libriform fibres and vessels. The vessels of the ischolar_main are wider than those of the stem. The ischolar_mains of Datura species deviate in their secondary xylem features from the rest of the taxa. These cross sectional configurations are easy access for identification of fragmentary stem materials.

Application/Improvements: An attempt will be made to prepare an artificial dichotomous taxonomic key involving anatomical and palynological data obtained during the present investigations.

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Background/Objectives: Some of the anatomical characters are liable to become modification in response to environmental change; however, many characters are more fixed genetically and such characters are to be employed for taxonomic studies. For distinguishing two species, differences in the anatomical structures usually provide much reliable grounds for identification.

Methods/Statistical Analysis: For anatomical studies the customary techniques of sectioning and staining will be followed. It is aimed to collect data of anatomical characters of easily available plant parts such as leaf, petiole, stem and ischolar_main. It is hoped that these studies will enable anybody to identify the plants concerned in the sterile or fragmentary conditions.

Findings: Anatomical structure is most likely to provide evidence concerning the interrelationships to families or in establishing the real affinities of genera of uncertain taxonomic status.

Application/Improvements: Microscopical studies are also very essential tool to establish the botanical identity of commercial samples of medicinal value and may also aid in checking adulteration or substitution. Apart from anatomical studies, palynological investigation is also to be attempted. This will give additional information both for diagnosis of the plants and for confirmation of their taxonomic position.

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Background/Objectives: The forest signifies the most intrinsic ecosystem complex. The ecological relationship of various components of the forest ecosystem is subtle and far to seek. Plant galls are outburst of repulsive reactions of the plant tissues to the stimulus incited by certain guild of phytophagous insects. In many cases, the galls induced by the parasites attain phenomenal structural complexity and architectural design which have allured the naturalists.

Methods/Statistical Analysis: To understand the mechanism involved in the morphogenesis and histogenesis in the normal growth of plant, cecidogenetic studies, similar to tissue culture and experimental methods, may also provide useful information and throw light on our perception of growth and development of plants.

Findings: The many plant galls are found to have medicinal properties. They have been used in traditional Indian Systems of medicine, especially Siddha and Ayurvedha. The gall nut of a Cynipid insect on the leaves of Quercusinfectoria, horn-shaped foliar gall on Pistasiaintegrima by Psyllid insect are popular gall drugs. Many fungal galls are also edible and eaten by tribals in many places.

Application/Improvements: Many practical applications may be attributed to ratiocinate the study of plant galls. Certain galls are said to be edible and some galls also claimed to be traditionally used as drugs.

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