Osmunda Regalis. Royal fern is a native to the Ozarks and grows tall each season as it is deciduous. It can reach 6 feet most seasons. They have lovely lime green to mid green fronds that unfurl in spring. They also have clusters of fertile spores at the tips of the fronds giving them a common name of flowering fern. Fibre used for potting orchids comes from the roots of these beautiful ferns. Full shade to part shade. 1.5m by 1m.