Scientific name: OsmundaceaeEnglish name: Vietnamese name: Ráng ất minh (Rau vi)Other name:
The Osmundaceae family of ferns is the only family of the order Osmundales, an order in the class Polypodiopsida or in some classifications the only order in the class Osmundopsida. This is an ancient and fairly isolated group, often known as the "flowering ferns" because of the striking aspect of their ripe sporangia. The sporangia are borne naked on highly dimorphic fronds. They are larger than those of most other ferns.
Ferns of this family form heavy rootstocks with thick mats of wiry roots. Many species form short trunks; in the case of the genus Todea, they are sometimes considered as tree ferns because of the trunk, although it is relatively short.
The leaf tissue ranges from very coarse, almost leathery in the case of the Cinnamon fern (Osmunda cinnamomea), to delicate and translucent, as in the case of the genus Leptopteris.