• Premise of the study: The classifi cation of the genus Salix has historically been intrinsically diffi cult due to its propensity toward plasticity and high variation in diagnostic morphological characters. We investigated leaf epidermal characteristics, focusing on the stomatal apparatus because it may provide critical insights into the evolution and taxonomy of Salix and its closely related genera.• Methods: Light microscopy was used to examine the leaf epidermal features in 32 taxa of Salix .• Key results: Characters such as shape, size, and density of stomatal complexes were very useful in differentiating Salix species. Variation in features of stomatal apparatus in Salix is wider than previously known. Moreover, the type of stomatal complex proved to be very helpful in discriminating Chosenia as members of the genus Salix .• Conclusions: The results of the present study support the placement of Chosenia within Salix and the combining of subgenera Chamaetia and Vetrix because of similarities in their unique stomatal apparatus.

This study was performed in order to compare two wild service tree populations (Sorbus torminalis (L.) Crantz) for their early growth and to find useful vegetative characteristics to be used in indirect selection of fast and tall growing trees of the species in the field. We used phenotypic and genotypic correlation coefficients estimated on data from 30 three-year old seedlings of each 40 randomly selected adult trees. Assuming genetic differences between the trees sampled, path analysis was performed on genotypic and phenotypic levels. Results showed that plus trees of one of the sites may be used for clonal seed orchard establishment. But the other site is suggested as a better site for breeding purposes with more effective Sorbus population. Collar diameter had the strongest positive direct effect and strongest correlation with plant height at the phenotypic level. In contrast, lateral branches showed very weak direct effect but relatively strong total indirect effect on plant height. Path analysis on the genotypic correlation coefficients detected negative indirect effect between the characters. Collar diameter could be regarded as a good predictor of plant height because of its strong direct and indirect phenotypic and genotypic correlations. The use of recommended selection criteria is discussed.

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Strategies to increase the leaf and flower essential oil yield of Mentha species would be improved by an understanding of how phenotypic and phenologic characters interact with one another in affecting the essential oil yield. In this study, path analysis was applied within some morphological and phenological characters recorded from field studies conducted in 2000 on four Mentha spp., M. longifolia M. spicata M. piperita and M. aquatica. Several morphological, phenological, and chemical characteristics were recorded on the experimental units, based on a three times replicated completely randomized design. The characteristics recorded on five single plants in each experimental unit were: main stem length, number of lateral branches on main stem, leaf length, leaf width, stem diameter, flowering date, percentage of flower essential oil, and percentage of leaf essential oil. After a confident result of differences between the species for the characters, path analysis was performed on the data. The analysis on flower essential oil-related characters revealed that the percentage of leaf essential oil and leaf length had a high direct effect on the dependent variable, flower essential oil yield. Flowering time showed a positive direct effect but a high negative total indirect effect through other independent variables on the dependent variable, resulting in a negative total effect on essential oil yield. The analysis on leaf essential oil-related characters showed that both stem diameter and flower essential oil yield had almost equal positive direct effects on leaf essential oil yield. Flowering date showed negative direct and total indirect effects on leaf essential oil yield. Stem length had a high positive indirect effect on the leaf essential oil yield through independent variables, counterbalancing negative direct effects to a positive total effect of 0.487. Among the species in the current study, genetic improvement in the stem diameter and length, leaf length and width would have beneficial effects on essential oil yield. Therefore, indirect selection may be done at the field for high essential oil yield based on morphological characters.