The systematic importance of anatomical data in Gagea (Liliaceae) from the Flora Iranica area

Anatomical features of basal leaves, pedicels and tepals of 22 species of Gagea belonging to four sections (Platyspermum, Plecostigma, Gagea and Didymobulbos) are investigated. Anatomical characters are mapped onto a molecular phylogenetic tree and their evolution is evaluated. The systematic importance of the anatomical characters is discussed. Anatomical characters are more systematically useful in the Irano-Turanian taxa than in Euro-Siberian taxa. The presence of collenchyma and/or sclerenchyma and the pentagonal outline of the transverse section of the basal leaf is found in Irano-Turanian taxa of section Platyspermum and is mostly absent in Euro-Siberian taxa. A diagnostic key based on combined anatomical characters is provided. The level of variation in anatomical characters is greater in the basal leaf than the pedicel and lowest in the tepals. Convergent evolution in anatomical characters is associated with ecological shifts between sunny, open, dry habitats and closed, humid habitats. (C) 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164, 155-177.