A researcher from Kobe University's Graduate School of Science has discovered a new plant species on Kuroshima, a subtropical island off the southern coasts of Kyushu in the Kagoshima prefecture.
Named Gastrodia kuroshimensis, the new plant species is mycoheterotrophic, which means it doesn't require photosynthesis for sustenance and instead relies on its host fungi, and cleistogamous, which means it produces flowers that never bloom.
Kenji Suetsugu, project associate professor from Kobe University, detailed his discovery in the journal Phytotaxa.
Mycoheterotrophic plants have long piqued the interest of researchers but there's little information on the species because they are hard to observe, given they are small in size, scarce and difficult to spot because they usually thrive in the dark understory of forests, with aboveground organs appearing only during fruiting and flowering periods.
Suetsugu has been studying mycoheterotrophic plants in Japan, documenting classification and distribution. In one of his trips in Kuroshima, he stumbled upon about a hundred individual plants of the mycoheterotrophic variant although the species was unknown to him. He collected a sample and conducted a detailed examination and confirmed that what he came across was indeed a new species. This was in April.
Aside from simply being a new mycoheterotrophic species, the plant Suetsugu discovered is unique because it is also completely cleistogamous. Literally translated as "a closed marriage," cleistogamy refers to plant species that have flowers capable of self-fertilization. However, the flowers have closed buds.
Cleistogamy evolution is also mysterious to researchers because cleistogamous plants also produce chasmogamous flowers, or those that participate in cross-pollination. Cleistogamous flowers, however, use up less resources and can offer better reproductive assurance since they can release seeds even under less-than-ideal environmental conditions. Additionally, they can adapt to local habitats by purging harmful gene variants.
The discovery of G. kuroshimensis provides a great opportunity to not only observe mycoheterotrophic plants further but to better understand cleistogamous species as well.
Along with other researchers, Suetsugu also discovered a new mycoheterotrophic species on the island of Yakushima in the Kagoshima prefecture back in February. Called Sciaphila yakushimensis, it is related closely to the Sciaphila japonica, a Triuridaceae species, but it differs in that it has a club-shaped pistillate with multiple papillae and a staminate no taller than its anther, and features dark purple-colored above-ground parts. The new species was named after the location it was discovered in.
The S. yakushimensis' discovery is seen by the researchers as evidence of symbiotic relationships between roots and fungi, although the network itself is hidden.