With 29 species in Iran, Polygonum L. is comprised of annual and perennial plants in different habitats. P. aviculare makes a species complex, hardly distinguished from P. arenastrum and P. patulum. In the present study, po-llen grains, fruit surface and petals and leaves epidermis features were used to provide diagnostic features in order to se-parate species from one another. In Total, 33 populations of 6 annual species, including P. aviculare, P. arenastrum, P. patulum, P. argyrocoleon, P. polycnemoides and P. olivascens were studied. Specimens were gathered during field trips and studied by means of light and scanning electron microscopes. The Pollen grains of all the species which were stud-ied were monad, subprolate or prolate spheroidal and tricolpate. Main differences were also observed in their surface ornamentations. Length of equatorial and polar axes and colpus, granules diameters and the average distance between granules were other diagnostic features of the pollen grains. Statistical analysis of epidermis features revealed that the length and width of epidermis cells and stomata length varied in the species studied. A close relationship was found between P. aviculare and P. arenastrum on the one hand and P. argyrocoleon and P. olivascens on the other. The sepa-ration of P. polycnemoides could be attributed to differences in epidermis features. Results showed that a selected set of these features to be of taxonomic importance.

Melissa officinalis is a medicinal plant belong to  lamiacea family.  This plant has been cultivated in many parts of the world due to its therapeutic effects. This study was conducted to improve antioxidant activities of proliferated shoots from tissue culture. The seeds of plant   were cultured in MS hormone free medium in order to obtain   seedlings. Then the  shoots were transfer to MS medium supplemented with 2 mg/ L  BAP.After 45 days salicylic acid (SA) was added to the medium at concentrations of 0, 50, 100 and 200 µM. The antioxidant activity and phenolics, flavonoids and rosmarinic acid content in proliferated shoots were evaluated 4,7,10 and 14 days after treatment. As a result the highest free radical scavenging and reducing power activity, as well as the highest value of total phenolic   and rosmarinic acid were observed in shoots   after 14 days of treatment with 100 µM salicylic acid. The elevated level of superoxide anion scavenging activity      and total flavonoids        were obtained from the shoots treated with 50 µM salicylic acid for 14 days. Over all treatment with100 µM salicylic acid for 14 days was better in order to antioxidant activity and compounds with recognized antioxidant activity.