Browsing items filed under: Fern × Requires Shelter × Heavy Clay Loam × Wetland/Bog × Cyathea medullaris Mamaku, black ponga Tallest of the tree ferns Cyathea smithii Soft tree fern Found throughout NZ in moist soils. Distinguishes itself from other tree fern species because of its 'skirt' of dead fronds that hang from the top of the plant.