This paper present studies on the morphological and biological characteristics of the species Oenothera biennis L. in the biological system, in the western Romania (Timis and Bihor counties) in two areas: one in the plain and one in the hill. The species is important from medical point of view; people's interest in medicinal plants has increased greatly due to side effects of drugs obtained by chemical leading to serious complications. The research was conducted under specific conditions of sustainable agriculture and the influence of experimental factors on the morphological and biological characteristics. The purpose of the researches was to increase knowledge on the behavior of the morphological and biological features. The experiences were place in the period 2011-2012 and they followed: plant height, ramifications number/plant, capsules number/plant, 1000 grains weight. The seed was produced at the Department of Crop. The researches were made in two periods of seed: March and October. We used different doses of natural fertilizer (50kg a.s. N/ha, 100 kg a.s. N/ha, and 150 a.s. N/ha). It is due to mention that 170 a.s. N/ha is the maximum amount of organic nitrogen allowed by national and European law to be used in the organic cultures. Average height was significantly closer between the two seed periods; number of ramifications/plant was also about the same, with minor differences, number of capsules/plant was grown with organic nitrogen dose, so the number of capsules / plant was less influenced by sowing period. Sowing in spring (March) , late autumn (October), do not influence the level of significance grains 1000 grain weight.

ramification, capsules, height, 1000 grain weight, plant.

Presentation: oral