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Bucknell Researchers Identify New Sexually Diverse Bush Tomato Species

Plant Discovery Challenges Notion of Binary Sexuality

LEWISBURG, Pa. — A new species of bush tomato discovered in remote Australia provides a compelling example of the fact that sexuality among Earth’s living creatures is far more diverse and interesting than many people realize.

Bucknell University postdoctoral fellow Angela McDonnell and biology professor Chris Martine led a collaborative team of scientists from the U.S. and Australia who documented their discovery in the botanical journal PhytoKeys. The authors noted that the plant has evaded classification for decades because of the challenge of identifying its typical reproductive form, which appeared at various times to be female, male or some combination of both.

“This plant is a great example of how sexual diversity is a consistent story across the living planet,” said Martine, the David Burpee Professor of Plant Genetics and Research at Bucknell. “What’s truly natural is lots of variability.”

“That variability, in turn, is what has caused this plant to not be named, even though it has been encountered in the field for years,” McDonnell added.

The researchers were able to collect numerous new specimens during a 2018 expedition to Australia. Their study gives the plant the new name, Solanum plastisexum, as a nod to the notable variation exhibited by this plant in its sexual condition.

“This name, for us, is not just a reflection of the diversity of sexual forms seen in this species,” the authors wrote in their study. “It is also a recognition that this plant is a model for the sort of sexual fluidity that is present across the Plant Kingdom — where just about any sort of reproductive form one can imagine (within the constraints of plant development) is present.”

The plant was first noted by Australian botanists during the 1970s. Herbarium specimens from those few earlier collections included notes regarding the challenge of identifying the sexual condition of this plant. When DNA studies in Martine’s lab offered proof that these plants were not only all the same thing, but a species not yet described, he and McDonnell joined with researchers from San Francisco State University and Northern Territory Herbarium in Australia’s Alice Springs to search for populations along the unpaved Buchanan Highway in the remote northwestern region of Australia.

Also known as the Dungowan bush tomato, Solanum plastisexum is a distant cousin of the cultivated eggplant and a close relative of two other Australian species recently discovered by Martine, his colleagues and his Bucknell students.

The scientists hope that the naming of this latest new species turns a spotlight on the fact that nature is full of examples for the myriad ways in which living things behave sexually.

“When considering the scope of life on Earth,” the authors conclude, “The notion of a constant sexual binary consisting of distinct and disconnected forms is, fundamentally, a fallacy.”

Bucknell sophomore Heather Wetreich, who measured and analyzed the physical characters of the new species using plants grown from seed in a campus greenhouse, joined Jason Cantley and Peter Jobson as co-authors on the publication.


CONTACTS: Chris Martine, 570-577-1135,; Angela McDonnell, 570-577-1700,; Mike Ferlazzo, 570-577-3212, 570-238-6266 (c),


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