whisk fern

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An epiphytic vascular plant (Psilotum nudum) of subtropical and tropical North and Central America, Asia, and Africa, having leafless green branching stems that bear spores.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various simple vascular plants, of the family Psilotaceae, that have leafless dichotomous stems and produce spores.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun chiefly tropical clump-forming plants of skeletal appearance resembling whisk brooms; lacking roots