Researcher Kenji Suetsugu of Kobe University has found flowering plants of a new species of orchid on Japan’s Amami-Oshima and Tokunoshima islands, now named Gastrodia amamiana.

G. amamiana belongs to a group of mycoheterotrophic orchids that live on dark forest floors, do not use photosynthesis to get their nutrients, and steal nutrition from fungi instead. G. amamiana’s flowers likely never open up or bloom.

Researchers have already found evidence of tree thinning close to where G. amamiana was discovered, and they worry that logging could dry the soil and consequently the fungi that the orchid depends on.

From Japan’s Amami-Oshima and Tokunoshima islands, researchers have described a new-to-science species of orchid that produces dark brown flowers that likely never bloom.

Kenji Suetsugu of the Kobe University Graduate School of Science, together with independent scientists Hidekazu Morita, Yohei Tashiro, Chiyoko Hara and Kazuki Yamamuro, came across the flower during a flora survey of the islands’ evergreen forests. When they looked at the orchid closely, they found that it belonged to the genus Gastrodia, a group of mycoheterotrophic orchids that don’t use photosynthesis to get their nutrients, instead stealing nutrition from fungi.

Suetsugu, who has been documenting Japan’s mycoheterotrophs and has described new species of such orchids in the past, has named the orchid from Amami-Oshima and Tokunoshima islands Gastrodia amamiana. He described the plant in a new study published in Phytotaxa.

Like many mycoheterotrophs, G. amamiana can be found lurking in the dark understory of forests where sunlight hardly penetrates. Without light, the orchid has evolved to find food without photosynthesis by relying on the network of fungi underneath the forest floor.

It has another peculiar trait: it bears fruit despite flowers that likely never open. Suetsugu posits that the plant probably self-pollinates because it lives on dark forest floors where insect pollinators like bees and butterflies seldom visit.

The act of opening up a flower uses critical resources, and without insect pollinators to open it for, the orchid may have evolved to never bloom, Suetsugu writes.

To date, G. amamiana is known from only two locations, one each on Amami-Oshima and Tokunoshima. In both locations, the researchers found some 20 flowering individuals within a dense forest dominated by the evergreen Itajii Chinkapin tree (Castanopsis sieboldii).

The Amami-Oshima forest where the species was found, however, could soon become logged, Suetsugu writes. The researchers have already seen evidence of tree thinning close to where G. amamiana was discovered, and the dry soil that results from this could dry out the fungi that the orchid depends on, he writes.

“These field surveys rely on cooperation from independent scientists, and our resources are limited, meaning that some species may reach extinction without ever being discovered by humans,” Suetsugu said in a statement. “The discovery of G. amamiana highlights the importance of the forests of Amami-Oshima. We hope that revealing these new species will draw more attention to the environmental threat faced by these regions.”

Citation:

Suetsugu, K. (2019). Gastrodia amamiana (Orchidaceae; Epidendroideae; Gastrodieae), a new completely cleistogamous species from Japan. Phytotaxa, 413(3), 225-230. doi:10.11646/phytotaxa.413.3.3