Sensitive-fern, bead-fern

In moist, open sites, sensitive fern may spread so much that it becomes a nuisance to agriculture.
The plant gets its name from the fact that it dies back when first touched by frost, and not from the belief that its fronds are sensitive to touch.
It is believed to be the oldest fern on earth, with its origins dating back some 60 million years (i.e. 10 million years after the dinosaurs disappeared).
It is important not to pick the fiddleheads of this fern, which resemble those of ostrich fern, but are considered to be toxic to horses.