A Remarkably Reduced Vascular Plant in the United States.

A clone-forming thallus lacking sex organs and propagating by gemmae occurs on rocks and tree trunks in the Appalachian region from Georgia to Virginia, Ohio, and Kentucky. Although bryophytic in appearance, the thallus is identified here for the first time as a greatly reduced variety of the vascular plant known as "shoestring fern," Vittaria lineata (L.) J. E. Smith, or a closely related species. The normally dominant sporophytic phase of the life cycle has been eliminated and the plant exists only as a vegetative prothallus.