Osmunda japonica

Osmunda japonica
Sterile Frond
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Polypodiopsida/Pteridopsida (disputed)
Order:	Osmundales
Family:	Osmundaceae
Genus:	Osmunda
Section:	Euosmunda
Species:	O. japonica
Binomial name
Osmunda japonica Thunb.

Osmunda japonica (Japanese royal fern or Japanese flowering fern; syn. Osmunda nipponica Makino) is a fern in the genus Osmunda native to eastern Asia, including Japan, China, Korea, Taiwan, and the far east of Russia on Sakhalin.

It is a deciduous herbaceous plant which produces separate fertile and sterile fronds. The sterile fronds are spreading, up to 80-100 cm tall, bipinnate, with pinnae 20-30 cm long and pinnules 4-6 cm long and 1.5-2 cm broad; the fertile fronds are erect and shorter, 20-50 cm tall.

It grows in moist woodlands and can tolerate open sunlight only if in very wet soil. Like other ferns, it has no flowers, but rather elaborate sporangia, that very superficially might suggest a flower, from which the alternative name derives.

Like its relative Osmundastrum cinnamomeum (Cinnamon fern), the fertile fronds become brown-colored and contain spores. The sterile (vegetative) fronds resemble in form, another relative, Osmunda regalis (Royal fern).

In Japan, the young frond of osmunda japonica (called zenmai in Japanese) is used as a vegetable.

Young frond in spring

References and external links

• Germplasm Resources Information Network: Osmunda japonica
• Flora of Taiwan: Osmunda japonica
• Plants for a Future: Osmunda japonica