- The Japanese Society for Plant Systematics
- Acta Phytotaxonomica et Geobotanica (ISSN:13467565)
- vol.71, no.2, pp.177-184, 2020-06-30 (Released:2020-07-31)
Two closely related species, Spiranthes sinensis and S. australis (Orchidaceae), have often been distinguished based on the presence or absence of hairs in their inflorescence and on the stems and ovaries: the stems and ovaries of S. australis are generally pubescent, whereas those of S. sinensis are reported to be glabrous. Although S. australis has not been documented to occur in Taiwan, we found a population of Spiranthes with slightly pubescent stems and ovaries at Tahanshan, southern Taiwan. Because the slightly pubescent plants may represent an undocumented extension of the distribution of S. australis, we attempted to identity the slightly pubescent plants by sequencing the ITS and trnL–F intergenic spacer regions. We also compared the lip and column morphology, which have diagnostic characteristics in Spiranthes, and the molecular and morphological data from S. australis, S. sinensis, their close relative, S. hongkongensis, and the unknown plants. The molecular analysis revealed the slightly pubescent plants to be heterozygous for the ITS sequences from S. australis and S. sinensis or from S. hongkongensis and S. sinensis, whereas the trnL–F intergenic spacer region was identical to that of S. sinensis. While we could not completely exclude the possibility that the unknown plants were hybrids between S. hongkongensis and S. sinensis based on the molecular data, we concluded that they were hybrids between the pubescent S. australis and the glabrous S. sinensis (Taiwan type) based on the lip and column morphology.