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Scientists have recently discovered a unique species of flowering plant on the coast of the Japanese Kuroshima Island. This plant is rare in that although it has most of the characteristics of a normal flowering plant, it neither photosynthesizes nor blooms.
The plant, G. kuroshimensis, is part of a group of rare mycoheterotrophic , or non-photosynthetic, plants. Not much is known about this group of plants because of their small size and the general difficulty of finding one in nature, where they are only known to be found in dark areas during their fruiting periods. The rarity of these plants and their ability to survive in difficult conditions makes scientists curious as to what potential long-term research could be done using this group of organisms.
The mycoheterotrophy of G. kuroshimensis means that rather than getting its nutrition from photosynthesis, the plant attains nourishment from host fungi that are attached to its roots. This species is also cleistogamous, which literally translates to “a closed marriage.” Cleistogamous plants have the ability to fertilize themselves and produce their own flowers. However, this self-fertilization means that in some cases, the plants do not bloom. In the case of G. kuroshimensis, the closed buds of the flowers prevent the blooms themselves from being seen externally.
Not much is known about the evolution of cleistogamous plants. Cleistogamy is a behavior most commonly found in legumes, such as peas, peanuts, and beans. The inconspicuous flowers of these plants do not secrete nectar and are often colorless. These plants can be found worldwide, but the unique characteristics of some species of cleistogamous organisms indicate that there is a correlation between environmental conditions and whether the plants will produce flowers that exhibit this characteristic or not. For example, the species impatiens capensis, or jewelweed, traditionally thrives in high-light environments, in which it produces an abundance of chasmogamous, or pollinating and fully-opened, flowers. However, in areas dissimilar to its preferred habitat, the plants become weak and only produce cleistogamous flowers.
The mycoheterotrophy of G. kuroshimensis is also one of its important characteristics. Mycoheterotrophy is thought to be a characteristic evolved from mycorrhiza, which is a similar symbiotic relationship between a fungus and a plant. In the mutual relationship that is mycorrhiza, the fungus receives carbohydrates from the plant, while the plant is able to provide nourishment for itself without photosynthesizing. This is similar to the relationship between plansts and host fungi in mycoheterotrophy. Plants resort to mycoheterotrophy when they are significantly lacking in chlorophyll or do not contain a photosystem that is able to function in photosynthesis. In order to gain nutrients, the roots of the plants and mycelium of the fungus are associated, allowing carbon to flow from the fungus to the plant.
Little is known about G. kuroshimensis at this point. Research is ongoing as to what causes this species to exhibit its unique characteristics and thrive in the environment that it does. With further research, scientists will hopefully be able to study and deeply investigate the evolution and more technical details of both cleistogamous and mycoheterotrophic plants in nature.