tree fern: any of numerous usually tropical ferns having a thick woody stem or caudex and a crown of large fronds; found especially in Australia and New Zealand; chiefly of the families Cyatheaceae and Marattiaceae but some from Polypodiaceae
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores
planetarium: an optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome