maidenhair: any of various small to large terrestrial ferns of the genus Adiantum having delicate palmately branched fronds
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores
solid: the state in which a substance has no tendency to flow under moderate stress; resists forces (such as compression) that tend to deform it; and retains a definite size and shape