MANCHESTER, N.H. (WHDH) - The New Hampshire Natural Heritage Bureau has confirmed its first documented global plant extinction.

The plant, smooth slender crabgrass, was previously only known to exist in Rock Rimmon Park in Manchester, N.H. This is the first documented plant extinction in the state and only the fifth in New England since European settlement. Its demise is likely due in part to heavy recreational use at the park.

Native to New Hampshire, this crabgrass, known scientifically as Digitaria laeviglumis, was different from weedy lawn-dwelling crabgrass.

Although samples of similar plants in Mexico and Venezuela initially were thought to be evidence of the grass’s existence elsewhere in the world, recent studies confirmed they are different grasses.

Specimens of the grass were first collected at the Manchester park by botanist Frank Batchelder in 1901 and were last collected in 1931. Since then, 24 botanical surveys which included searches for the grass were unsuccessful.

“The high number of smooth slender crabgrass collections from 1931, made by botanists as a way to formally document the species, may have inadvertently contributed to its demise,” said Bill Nichols, senior ecologist and state botanist at the N.H. Natural Heritage Bureau. “But more traceable impacts on its environment – including heavy recreation use, severe soil erosion on the summit and competition from non-native crabgrasses – also likely contributed to its being designated globally extinct.”

Rock Rimmon is known to botanists as a hot spot. Plant records dating to 1899, document 10 state-endangered and state-threatened plant species.  The Natural Heritage Bureau has determined that five of the 10 rare plant species previously documented at the park, including smooth slender crabgrass, are no longer there due to human-related activities.

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