 To add strength, there are deposits of lignin in the cell walls and the lower part of the stem is reinforced with thick, interlocking mats of tiny roots.If the crown of "Dicksonia antarctica" (the most common species in gardens) is damaged, it will inevitably die because that is where all the new growth occurs.But other clump-forming tree fern species, such as "D. squarrosa" and "D. youngiae", can regenerate from basal offsets or from "pups" emerging along the surviving trunk length.