XVI International Botanical Congess

Achillea sect. Santolinoidea (DC.) O. Hoffm. consists of 23 perennial species, occurring in xeric habitats of the Irano-Turanic region. Comparative analyses of leaf and floral characters contradicted the supposed macromorphological uniformity (in prep.). Growth forms are defined as further and new characters for species of this section. Their elements, as determined by time, space and environment, comprise: persistency of basal parts, innovation, lignification, and rooting system. Five different types are distinguished within sect. Santolinoidea, providing further distinctive characters. Their taxonomic relevance was recently proved in a case of species alignment (Valant-Vetschera & Kaestner, 1998: Feddes Repert. 109, 501).