Ethereal new plant species do not use photosynthesis
Cloaked in the shadows of enchanting Asian forests, strange growths can peek through leaf litter like the ghosts of long-extinct flowers.
The plant’s foliage lacks green pigment because they have given up photosynthesis in favor of an alternative source of nutrients on the forest floor, a source stolen from fungi that many other plants consider friends – the symbiotic mycorrhizae which connect most forest plants into one wood wide web.
Widely found in East and Southeast Asia from the Himalayas to Japan, Low monotropastrum was thought to be a single species. Now researchers from Japan and Taiwan have discovered a pink-hued species that is a unique species in its own right, one they have named Monotropastrum krishimense.
Wood-wide webs — incredible networks of fungi and plant roots that span entire forests — act as highways for nutrient delivery and as threads for transmitting information between plants via electric and chemical signals. These connections help strengthen a forest as a whole by distributing resources from nutrient-poor to nutrient-rich areas of the network. They also allow plants warn each other of predators and even help protect them from drought.
In exchange for these services, plants pay their fungal allies with a portion of the hydrocarbons they produce using photosynthesis.
But Monotropastrum betrays this mutualistic relationship by stealing all its nutrients from the fungi and in return offering no photosynthetic products to the network – making them part of a highly selective mycoheterotrophic club.
The most striking feature of the newly described Japanese variety is the blushing pink petals and sepals, but there are other differences as well, the researchers note.
Unlike their cousin M low, the roots of the newly discovered plant barely protrude from the ground. They are also more strongly associated with one Russula lineage of mycorrhizae, while M low favors an entirely different variety of fungi.
What’s more, despite growing side by side, M. Kirishimense flowering season does not overlap with that of M low, flowering 40 days after the better known species. This study of these life cycle interactions and between wildlife and physical forces on Earth, such as seasons, is called phenology.
“Our multifaceted evidence leads us to conclude that this taxon is morphologically, phenologically, phylogenetically and ecologically distinct and should therefore be recognized as a separate species,” Kobe University ecologist Kenji Suetsugu and colleagues conclude in their paper.
“Our study presents the exciting possibility of a host changing M. kirihimensetowards a specific Russula lineage, caused ecological speciation.”
Their different blooming seasons make for the primary pollinator they share, the bumblebee Another bombcannot accidentally give one species the pollen of the other, preventing hybridization.
Many of the world’s forests are under threat and if Monotropastrum species depend on old-growth forests, these strange plants are also vulnerable to extinction. M. kirihimense is rare and the researchers suspect it is likely endangered.
The new factory was described in the Plant research journal.
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