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A plant species found only in N.H. has been declared extinct

Rock Rimmon Park in Manchester was home to the only smooth slender crabgrass known to the world.
Bill Nichols
Courtesy of Bill Nichols
Rock Rimmon Park in Manchester was home to the only smooth slender crabgrass known to the world.

Smooth slender crabgrass is officially gone from the world. New Hampshire’s Natural Heritage Bureau confirmed the first documented plant extinction in the state this week.

The unique native plant was different from the crabgrass weeds found in today’s lawns. The only place in the world it was known to exist was in Rock Rimmon Park, in Manchester.

Bill Nichols, senior ecologist and state botanist at the New Hampshire Natural Heritage Bureau, said the park is a botanical hotspot. The bedrock there has more nutrients available for plants than other places, making Rock Rimmon a good home to a variety of rare plants.

But smooth slender crabgrass hasn’t been spotted there since 1931.

Nichols said a variety of factors led to the plant’s demise, including recreational uses of the park, soil erosion and competition from non-native grasses. Researchers collecting too many samples of the crabgrass also could have contributed, he said.

Smooth slender crabgrass collected when the species was last seen in 1931
New England Botanical Club-Harvard University Hebaria
Courtesy of N.H. Department of Natural and Cultural Resources
Smooth slender crabgrass collected when the species was last seen in 1931

Though scientists haven’t seen the crabgrass in nearly a century, Nichols said confirming a plant extinction is hard work.

“We want to be thorough because of the responsibility of declaring the species extinct,” he said. “The loss of a native species is not good news. But there's also a sense of relief that we've gotten to this point where we could actually collect the type of data that would support what we believed for 15 years.”

His team had to determine that smooth slender crabgrass was regarded as a valid species, and that it was only known to be in Manchester. Similar plants were found in Mexico and Venezuela, but researchers ultimately determined that they were different species.

Nichols also had to figure out how many times others had searched for the plant and come up empty-handed since it was last seen.

“We feel that it's very likely there’s been 24 searches that at least in part tried to rediscover the crabgrass in Rock Rimmon,” he said.

Ultimately, his team found enough evidence to declare smooth slender crabgrass globally extinct.

And even for a small plant, the loss matters. Nichols said we can think of species like rivets holding the wings on an airplane. If the plane loses a lot of rivets, or if one really important rivet breaks, the wings will fall off.

“We're all currently passengers on the plane called Planet Earth,” he said. “So whether it's the loss of a keystone species or the loss of several species that eventually lead to serious repercussions, the significance of the loss of the species is meaningful.”

The crabgrass is the fifth documented plant extinction in New England since European colonization.

Mara Hoplamazian reports on climate change, energy, and the environment for NHPR.

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