Ophioglossum engelmannii, commonly known as the limestone adder's-tongue,[1] is a species of fern native to the Western Hemisphere.

It is widespread and native to the United States, Mexico, and Central America.

[1] Its primary natural habitat is dry barrens and glades in calcareous areas.

[2] It is a small species that produces leaves in the spring and dies back in the summer.

A second growth of leaves is sometimes produced with the fall rains.