A Comprehensive Review of the Morphological and Molecular Taxonomy of the Genus <i>Helleborus</i> (Ranunculaceae)

Abstract

Helleborus is a small genus of the Ranunculaceae family and comprises about 19 species of herbaceous perennials. These perennial plants have a long flowering period and are mainly evergreen. Helleborus cultivars, including H. niger (commonly called Christmas rose), are a highlight in winter gardens and bloom from winter until early spring, at a time when few other flowers are in bloom. Taxonomy of the genus Helleborus was previously based only on morphological characteristics; however, molecular studies have been done in the past 20 years and further such research will provide comprehensive genetic information. This genus has a rich and diverse group of flower shapes. This review provides a general introduction to the genus Helleborus, focusing on the two different taxonomic methods: morphological and molecular. Several molecular tools used for phylogenetic studies are summarized and evaluated for their applicability in future studies of Helleborus taxonomy.