The research is a multidimensional including pharmacognostic, phytochemical evaluations and pharmacological activities and was conducted during 2009 – 2011 on Datura innoxia Miller, Solanum surattense Burm.f., Solanum nigrum Linn, Withania coagulans (Stocks) Dunal and Withania somnifera Linn. The pharmacognostic studies showed that Datura innoxia root was slightly pungent, cylindrical and had fibrous fracture while stem was slight green with trichomes. Leaves were alternate, dentate and ovate and fruits were succulent and capsule. Solanum nigrum root had uneven fracture while stem was dark green with trichomes. Leaves were sinuate to irregular dentate and ovate and fruits were berry. Solanum surattense root had uneven & fibrous fracture while stem was prostate, dark green, leaves were pinnatifid and elliptic oblong and fruits were berry. Withania somnifera root had fibrous fracture while stem was errect, shrubby, leaves were ovate, acute, entire and fruits were berry. Withania coagulans root had fibrous fracture while stem was errect, shrubby, leaves were ovate, obtuse, entire and fruits were berry. The anatomical study of the root exhibited that the roots of these plants had epidermis, casparian strips, tracheae, medullary rays, vascular bundles, while the stem contained epidermis, hypodermis, vascular tissues, pith, medullary rays, endodermis, pericycle, cortical cells were present in all the five plants that were investigated and besides these idioblast cells were only present in the stem of S. nigrum. The vein islet number was highest (22.5 – 27.75) in W. coagulans and was lowest (11.5 – 16.5) in D. innoxia, while the vein termination number was highest (22.5 – 26.75) in W. somnifera and was lowest (11.75 – 17.5) in W. coagulans and the palisade ratio was highest (27.5 – 34.5) in W. coagulans and was lowest (10.75 – 18.5) in S. nigrum. The study reported variation in the structure and distribution of stomata in these plants and included types, frequency, density, stomatal index, size of guard cells & stomatal pore and percentage of the open and close stomata. In these five plants the upper epidermises contain anisocytic, anomotetracytic and amphianisocytic and the lower epidermises of these plants contain paracytic, anomotetracytic, anisocytic and amphianisocytic. The statistical evaluation of the stomata and epidermis included mean, variance, standard deviation, coefficient of variance, standard error and 95% confidence interval for mean. Alkaloids, saponins, proteins, fats, anthraquinone derivatives, cellulose, calcium oxalates were present in all parts of the plants species while mucilage, starch and tanins were present in some parts while absent in other parts of the same plants. ANOVA showed that ash and moisture contents was non significant between the plant parts and phenological stages. Crude protein was non significant between the plant parts and phenological stages except for Datura innoxia parts but not for its phenolgical stages. While crude fats were non significant between the plant parts and phonological stages except for S. nigrum and S. surattense parts but not for their phenolgical stages. Crude fiber was non significant between the plant parts and phonological stages except for Datura innoxia parts but not for its phenolgical stages. And carbohydrates was non significant between the plant parts and phenological stages except for the phenolgical stages of S. surattense and W. coagulans. The mineral analysis showed the presence of Cr, Zn, Cu, Mn, Fe, Ca, K, Mg and Na in the roots, stems, leaves, flowers and fruits of the plants in three different phenological stages. Only the micro-minerals were present in traces while the macro- minerals were present high quantities as compared to the micro-minerals. The methanolic extract of D. innoxia exhibited maximum activity against Escherchia coli and minimum activity against Klebsella pneumoni, S. nigrum showed maximum activity against Pseudomonas aeruginosa and minimum activity against Staphylococcus aereus, S. surattense showed maximum activity against P. aeruginosa and minimum activity against Salmonella typhi, W. somnifera exhibited maximum activity against K. pneumoni and minimum activity against S. typhi, W. coagulans exhibited maximum activity against S. typhi and minimum activity against S. aereus. The methanolic extract of the D. innoxia, S. surattense and W. somnifera showed maximum activity while in case of S. nigrum and W. coagulans the acetone extract exhibited maximum activity against the bacterial strains. As far as the antifungal activity the methanolic extract of D. innoxia exhibited maximum activity against Aspergillus parasiticus and low activity against Fusarium solani, S. nigrum showed maximum activity against A. parasiticus and low activity against A. flavus and Candida glabarata, S. surattense showed maximum activity against C. glabarata and low activity against F. solani, W. somnifera exhibited maximum activity against Candida albicans and low activity against C. glabarata and W. coagulans showed maximum activity against Aspergillus niger and low activity against A. flavus. Overall the methanolic extract showed maximum activity as compared to the acetone extract. All the plants showed cytoxicity to some extents. The LD50 of the methanolic extract of D. innoxia was 94.86, S. nigrum was 93.73, S. surattense was 95.18, W. somnifera was 93.66 and W. coagulans was 94.86. LD50 of the acetone extract of D. innoxia was 87.75, S. nigrum was 86.78, S. surattense was 74.31, W. somnifera was 86.56 and W. coagulans was 93.66. Both the methanolic and acetone extracts of the all the plants are phytotoxic in nature. But the toxicity varied with the change in concentration. The maximum toxicity (87.27%) was exhibited by the methanolic extract of D. innoxia at the concentration of 10 μg/ml and lowest toxicity (54.54%) was showed at the concentration of 1000 μg/ml by W. coagulans. The maximum toxicity (92.72%) was exhibited by the acetone extract of S. nigrum at the concentration of 10 μg/ml and lowest toxicity (54.54%) was showed at the concentration of 1000 μg/ml by D. innoxia, S. nigrum and W. coagulans. The maximum mortality was exhibited by methanolic extract of D. innoxia against Callobrochus analis and the minimum mortality was exhibited against Rhyzopertha dominica, S. nigrum showed maximum mortality against Trochoderma granarium and the minimum mortality against R. dominica. S. surattense exhibited maximum mortality against Sitophilus oryzae and the minimum mortality against T. granarium, W. somnifera showed maximum mortality against R. dominica and the minimum mortality against C. analis and W. coagulans exhibited maximum mortality against C. analis and the minimum mortality against R. dominica. Generally the methanolic extract showed the maximum mortality against these insects however, there were very few insects against which the acetone extract exhibited maximum mortality viz, D. innoxia against Tribolium castaneum, S. nigrum against R. dominica, S. surattense against C. analis.