Morphological and Karyological Characteristics and Phylogenetic Relationship of Asarum cordifolium C. E. C. Fisch. (Aristolochiaceae) Occurring in Myanmar

Abstract

To make clear the morphological and karyological characteristics and the phylogenetic relationship of the poorly known species 'Asarum cordifolium' from Myanmar, we undertook morphological and karyological studies and phylogenetic analyses of 18 taxa including 14 accessions of Asarum and Saruma. Morphologically, Asarum cordifolium appeared to be assigned to section Asarum in sharing some floral aspects: connate styles, inferior ovary, free sepals beyond the attachment to ovary, and stamens with longer filaments. However, unlike the most species of the section Asarum, the species had foliage leaves alternate to each other and vertically oriented rhizomes, and its somatic chromosome number was 2n=24. Phylogenetic analyses based on ITS regions indicate that A. cordifolium is positioned within the section Asarum and is closely related to A. caudigerum and A. cardiophyllum.