Bush Tomato Classified as World’s First Gender-fluid Plant

After decades of perplexity over its nonbinary flowering forms, botanists finally figure out what the Solanum plastisexum of Australia’s Outback really is

The bush tomato, first noticed in the Australian Outback in the 1970s.
CHRIS MARTINE

Most countries have “national” animals, plants and foods. Now, after decades of studying it in puzzlement, botanists have given a name to what has to be the ideal mascot for sexually ambiguous millennials: the first-ever gender-fluid plant.

It is, wonderfully, called the bush tomato. You can’t make this stuff up.

“When considering the scope of life on Earth,” write Bucknell University biology postdoctoral fellow Angela McDonnell and Prof. Chris Martine in the journal PhytoKeys, “The notion of a constant sexual binary consisting of two distinct and disconnected forms is, fundamentally, a fallacy.”

The bush tomato has elongated furry leaves and sports purple flowers, and in fact was noticed in the Australian Outback in the 1970s. But it eluded formal classification all this time. Why? Because of the atypical fluidity of its flower form. Botanists couldn’t get a handle on what the thing was doing.

A single individual bush tomato plant can manifest multiple reproductive forms, which is definitely outré anywhere, including in the plant world. It is, write the scientists, a “compelling example of the fact that sexuality among Earth’s living creatures is far more diverse — and interesting — than many people likely realize.”

Note that bisexuality in flowers is absolutely the norm: About 85 percent of the planet’s quarter-million flowering plants have both male and female organs in every blossom. Ironically, marijuana plants are among the conservative minority, with plants being either male or female.

Gender fluidity is a new one. The scientists explain that the plant is andromonoecious, meaning a single plant can appear at various times to be female, male or bisexual. The name they gave the plant is Solanum plastisexum. 

The fruit of the gender-fluid bush tomato
McDonnel

“What makes Solanum plastisexum stand out is that it is one of just a few plants that kind of do it all,” remarks Martine. “It really seems like you never know what you’ll get when you come across it.” 

After decades of bewilderment, genetic testing in Martine’s lab proved that the plants were all the same thing — and an unknown species to boot.

The bush tomato actually belongs to a vast order of plants that exist on almost all continents: the Solenales, which exist on all continents except Antarctica. The group is so big, it has its own subspecies of scientist studying it: solanologists.

Solenales include morning glories and nightshades, which include a vast range of edibles like tomatoes, potatoes, sweet potatoes and bell peppers; flowers like petunias; and a host of weeds, including tobacco.

They seem to have evolved in the supercontinent Gondwana but only reached Australia quite late — just 5 to 10 million years ago — and their fruit looks like a small green tomato. Australia has a large number of bush tomato types but most are not edible. You have been warned.