Flowerring Fern "Zenmai" sprouts about from April to June and those sprouts are covered with cotton.
Zenmai is distributed in the Korean Peninsula, China, Taiwan and the Himalayas.
The same kind of Zenmai is distributed worldwide except Australasia.
There are Yamadori Zenmai / Cinnamon Fern (Osmunda cinnamomea),
Yasha Zenmai (Osmunda lancea), Oni Zenmai (Osmunda claytoniana),
Royal Fern (Osmunda regalis), besides Zenmai (Osmunda japonica).
The cotton of zenmai is often used to the body of traditional tenkara fly.
The people who lived in the mountain village spun the cotton of zenmai into thread and made the winter clothes in the old days
because this material has performance of water proof.
It can be said that it is a wisdom of the mountain village's people.
And it is also well known that the sprouts dries and becomes food.