Color Variation in the Mycoheterotrophic Yoania japonica (Orchidaceae)

Abstract

Due to the lack of chlorophyll, fully mycoheterotrophic plants display wide variation in pigmentation in their vegetative as well as in their floral parts. Here, we describe a creamy yellow form of Yoania japonica Maxim. discovered in Tateshina city, Kita-Saku-gun, Nagano Prefecture. This is another example of a mycoheterotrophic orchid that exhibits a distinct color difference from the typical form. While in the genus Yoania, creamy yellow coloration has been reported only in Y. flava, our materials are distinguishable from Y. flava by the morphology of the lip and petal margins (erose- serrate vs. almost entire). The ecological significance of this creamy yellow form of Y. japonica in the vicinity of the boundary between the distribution of Y. japonica and Y. flava is also discussed.