Distribution, karyomorphology, and morphology of Aspidistra subrotata (Asparagaceae) at different ploidy levels in limestone areas of Asia

Aspidistra subrotata Y. Wan & C.C. Huang, 1987 is considered for the first time as a widespread polyploidy complex in the genus Aspidistra Ker Gawler, 1823 from limestone areas of Asia. The chromosome number of the tetraploid is 2n = 76 and the karyotype is formulated as 2n = 44 m + 8 sm + 24 st, while the chromosome number of the diploid is 2n = 38 and the karyotype formula 2n = 22 m + 4 sm + 12 st. In our studies, diploids occupy broader geographical and environmental niche spaces than tetraploids. Although the leaf-shape of Aspidistra subrotata varies quantitatively between and within diploid and/or tetraploid population(s), no obvious discontinuity in the width of leaf has been observed. The tetraploid plants may be distinguished from the diploid plants by their rigid petioles as well as thick deep green lamina. Aspidistra subrotata is therefore an interesting material to explore the formation and the evolutionary dynamics of a natural polyploid complex from limestone areas of the tropical regions.