Noun | 1. | ![]() fern - any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores genus Trichomanes, Trichomanes - bristle ferns; kidney ferns hare's-foot bristle fern, Trichomanes boschianum - a variety of bristle fern Killarney fern, Trichomanes speciosum - large stout fern of extreme western Europe kidney fern, Trichomanes reniforme - large fern of New Zealand having kidney-shaped fronds |