Discovery of a Japanese plant that neither photosynthesizes or blooms

by Lillian Stanton · 18th October 2016

A new species of plant, named Gastrodia kuroshimensis, has been discovered on Kuroshima Island in Japan. It is thought to be significant and rare as it it both mycoheterotrophic and uniquely cleistogamous, ie. it neither photosynthesizes or blooms.

Gastrodia-kuroshimensis (c) Kenji Suetsugu/Kobe University

Mycoheterotrophic plants are plants that obtain their nutrients from mycorrhizal fungi attached to its roots. Mycorrhizal fungi lives symbiotically on the roots of over 80% of plant species. Normally the plant would provide the fungi with 5 to 10% of complex carbons from its photosynthase. And the fungi helps fixate nitrates from the surrounding soil with nitrate being essential in plants for efficient development. However, contrary to the plant ‘norm’, mycoheterotrophic plants are the parasite part of the symbiosis between plant and fungi: The plant obtains all of its complex carbons, instead of from photosynthesis, from the mycorrhizal fungi. Thus near all Mycoheterotrophic plants have no leaves and can survive almost in total-darkness.

Gastrodia kuroshimensis was identified as a new species due to its significantly different flower morphology. The plant appears to belong to the Gastrodia Brown genus, a group of over 90 mycoheterotrophic orchid species. They are found in both temperate and tropical regions in Asia, Oceania, Madagascar and Africa and are characterised by their lack of leaves and their fleshy tuburs.

Gastrodia kuroshimensis (c) Kenji Suetsugu/Kobe University

Cleistogamous plants reproduce and propagate automatically using closed, self-pollinating flowers. This type of pollination and reproduction is most commonly observed in grass species as well as both the pea and the peanut plant. Self-pollination is common in the orchid family with over one third of species resorting to this type of reproduction. It is thought to have developed in plants inhabiting dense woodland floors where there is both a lack of light and also, in some climates, a lack of pollinators.

Contrary to most Gastrodia members, which adapt a mixed pollination strategy of both cleistogamous (self pollinating) and chasmogamous (for insect-mediated pollination) flowers , the most significant character of Gastrodia kuroshimensis is that it has uniquely cleistogamous flowers.

Studies of such plants could help scientists establish a better understanding of plant evolution and survival.

Reference: Suetsugu, K. (2016) ‘Gastrodia kuroshimensis (Orchidaceae: Epidendroideae: Gastrodieae), a new mycoheterotrophic and complete cleistogamous plant from Japan’ Phytotaxa 278 (3): 265–272.

Read the full paper here: http://biotaxa.org/Phytotaxa/article/view/phytotaxa.278.3.6/23756

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