fiddlehead ferns: fiddleheads are young, edible fern shoots that are gathered when they are still curled. they are very similar in shape to the head of a violin, hence their name. these vegetables are gathered in the spring when they are still tightly curled and between 4 and 6 inches high. this period lasts for about 15 days between midapril and early july, depending on the region. fiddleheads must be collected just days after they emerge, as the plants become inedible once they uncoil. north american indians appreciated fiddleheads long before the arrival of europeans. the plant has also been known to the japanese and the aboriginal peoples of australia and new zealand. there are thousands of varieties of ferns, only a few of which produce edible shoots. edible varieties include the ostrich fern and the buckhorn, or cinnamon fern. the fiddleheads of the bracken fern, which are highly prized in japan, contain a carcinogenic substance that can be neutralized by roasting the plants before using them. brakes rise in single fronds, and the fiddleheads are more bitter tasting than those of the ostrich fern.