Noun | 1. | Helminthostachys zeylanica - Australasian fern with clusters of sporangia on stems of fertile fronds fern - any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores genus Helminthostachys, Helminthostachys - one species: terrestrial fern of southeastern Asia and Australia |