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On sheer rock walls in West Africa, a small, unassuming plant carries a genetic trait that does not belong in its family, disobeying the usual rules of inheritance.
This discovery challenges long-held assumptions about how plants change, adapt, and pass traits forward across generations.
Meet Virectaria stellata
The plant, Virectaria stellata, was identified at three sandstone sites in Guinea after botanists noticed its unusual star-shaped hairs and traced their origin to possible gene transfer rather than ordinary mutation.
Botanical surveys in 2019 targeted Guinea’s sandstone escarpments while teams mapped sites for national plant conservation planning.
The work was led by botanist Faya Julien Simbiano at Université Gamal Abdel Nasser de Conakry (UGANC).
His research focuses on documenting Guinea’s rare cliff plants, while partners at Royal Botanic Gardens, Kew (RBG Kew) handle global comparisons.
Researchers recognized the plant as a new Virectaria species when its flowers and fruits matched the genus but not known species.
Specimens came from Forécariah and Kindia prefectures, and UGANC teams collected flowering shoots on November 1, 2019 and later dates.
Mapping those collections showed the species stays local, a pattern common for plants tied to rare rock habitats.
Star-shaped hairs
Microscopes revealed stellate hairs, star-like plant hairs with many arms, covering the stems, leaves, and flowers.
“Virectaria stellata has stellate hairs, recorded here for the first time in the family Rubiaceae,” said Simbiano.
Because the Rubiaceae family lacks this hair type, the finding pushed the team to ask how it appeared.
Plant surfaces often grow trichomes, tiny hairs made from skin cells, to manage heat, water, and pests.
On exposed rock, these outgrowths trap a thin layer of air, which slows evaporation from the leaf surface.
That protective effect could help the species survive long dry spells, yet it does not explain the unusual branching.
Virectaria stellata‘s plant family
Several Acanthaceae, a plant family that includes Barleria, carry stellate hairs with one arm much longer.
The paper points to Barleria species in Guinea whose hair microstructure resembles the arms seen on the Virectaria stellata species.
Similarity alone can mislead, because unrelated plants sometimes evolve matching traits when they face the same stresses.
The researchers suspect horizontal gene transfer, DNA moving between species without sex, as a reason for the strange hair architecture.
In plants, bacteria can insert genes into cells, and that DNA can persist if it reaches seeds or pollen.
Cultivated sweet potato already carries bacterial DNA in its genome, showing the process can happen in nature.
Parasites can trade genes
Some plant parasites connect directly to a host’s tissues, creating shared channels where genetic material can slip across.
Transcriptome analyses, the RNA readout of active genes, found dozens of gene transfers in parasitic Orobanchaceae, using gene family trees as evidence.
Because the Virectaria stellata species is not parasitic, the route for any borrowed genes remains uncertain.
Mitochondria show another route
In some cases, organelles swap DNA when plants grow close together, especially where stems wound and tissues touch.
A study of Amborella trichopoda reported a mitochondrial genome packed with foreign DNA, likely acquired through mitochondrial fusion.
That kind of exchange usually involves organelle DNA, so it may not explain a hair trait controlled by nuclear genes.
Hair branching needs many genes
Hair cells in Arabidopsis thaliana helped scientists track genes that control when a single cell branches during growth.
Mutations in at least five genes can change trichome growth and branching, showing that shape depends on several genetic switches.
If many genes must change at once to build stellate hairs, researchers need stronger evidence than appearance alone.
Looking for a near relative
A specimen collected on September 25, 2019 lacked stellate hairs but otherwise looked strikingly similar to the species.
Collectors found that plant about 56 miles north of the known sites, and its longest hairs were transparent and spiralled.
That mix of traits could mark an ancestor or a separate species, so genetic sampling across Guinea becomes essential.
How to test gene transfer
Genomic sequencing can compare the species to close relatives, and RBG Kew collections help choose those relatives for testing.
Researchers build phylogenetic trees, DNA family trees used to track ancestry, and compare them across genes to spot conflicts.
Even then, the team must rule out lab contamination and independent evolution before calling the case true gene transfer.
Living on vertical sandstone
Vertical sandstone walls in Guinea hold small soil pockets, and the species grows where cracks offer shade or sun.
Field notes place populations between 1,476 and 2,986 feet, where roots wedge into rock and tap brief runoff.
Such narrow niches can produce endemic species quickly, yet the same isolation also limits how far seeds can spread.
Lessons from Virectaria stellata
Conservation reviewers estimated the known range at about 47 square miles, and they did not report major threats.
Dry-season fires lit by herders can scorch plants near the cliff base, but buds on stems often resprout.
Least Concern is only a snapshot, so UGANC and RBG Kew still plan follow-up checks as mining and climate stress expand.
Taken together, the evidence links an odd hair trait in the species to the broader story of gene movement.
Genomes from Virectaria and nearby Barleria will decide whether the case reflects real transfer or another path to the same form.
The study is published in Webbia.
Image credit: University of Florence
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