Comparative Anatomical Leaf Analyses оf Carduus nutans and Carduus thoermeri from Bulgaria

The present study provides a comparative anatomical leaf analysis of Carduus nutans L. and C. thoermeri Wienm., which belong to the Asteraceae family. Bifacial leaf structure, anomocytic and anisocytic types of stomatal apparatus and two types of trichomes (multicellular covering and glandular) were found on the leaves of both species. The quantitative anatomical characteristics varied considerably, however; basing on the statistical analyses, the most significant characteristics for distinguishing the two taxa are: the number of stomata in the abaxial epidermis, the number of capitated glandular trichomes and the number of multicellular covering trichomes in the upper (adaxial) and lower (abaxial) epidermis.