Abstract:

We investigated the morphological variations of non-glandular hairs across 16 cultivated Epimedium sagittatum (Berberidaceae) populations using digital photomicrography. The main features examined included the total numbers of cells, the full-length and ratio of the first cell, the angle and connection pattern between the first and adjacent cells, the presence of elongated cell(s), and the shape, diameter and cell wall thickness of the first cell. Of these, the shape of the first cell was the most important variable and was associated with such characters as the full length, the presence of elongated cell(s), the ratio of the first cell, and the diameter and cell wall thickness of the first cell. Morphological diversity among populations was significant with two main groups identified, namely as sword-shaped group and a fusiform group. However, variations of the main characters was continuous among individuals and populations, suggesting that E. sagittatum was possibly a polytypic species. Adaptive divergence of key traits between populations caused by natural selection was also possible. The genetic basis of variation was evidenced by morphological differences maintained among populations cultivated in a common garden. Phenotypic divergence between ecologically separated populations could be the result of local adaptation.

Key words: population genetic heterogeneity, genetic heterozygosity, habitat fragmentation, gene flow