Calanthe xhsinchuensis (Orchidaceae), a new natural hybrid from Taiwan

Natural hybridization in plants is a vital mechanism of speciation. Calanthe arisanensis and C. sieboldii occur in the same habitat in northern Taiwan, where there are a number of plants whose morphologically characters are similar in between of these two species. In this report, a new natural hybrid, Calanthe species – C. xhsinchuensis Y.I. Lee putatively derived from the natural hybridization of C. arisanensis and C. sieboldii was described and illustrated. Besides, somatic chromosome number was counted. The morphological and histological data of flowers, capsules, roots and leaves of C. xhsinchuensis show an intermediate condition between its putative parents. The chromosome number, 2n = 40, is also congruent with its putative parents. Color plates and line drawings are provided to aid in identification. Base on the morphological characteristics of reproductive and vegetative organs, and the distributions of putative parents, it is proposed that C. xhsinchuensis is a natural hybrid between C. arisanensis Hayata and C. sieboldii Decaisne ex Regel.