Botrypus virginianus aka Rattlesnake Fern

Botrypus virginianus is also known as rattlesnake fern. It belongs to the fern family Ophioglossaceae. Sources also use the name Botrychium virginianum. This fern lives for more than one year. It grows across the Americas and temperate parts of Eurasia. Its range covers much of North America, Europe, and Asia. It reaches Central America and parts of South America too. It grows in rich woods and shaded forests. It also grows where shrubs have grown back. Dry regions have few or none of these ferns.

This fern has a short, upright, fleshy rhizome, or underground stem. Many fleshy roots grow beneath it. One source gives a usual height of 0.8–2.3 feet [0.25–0.70 metres]. NC State lists a wider range of 0.5–4 feet [0.15–1.22 metres]. Its listed spread is 0.7–1 foot [0.20–0.30 metres]. The plant grows at a medium rate. NC State says it sheds its leaves each year. It grows upright, with arching fronds and a fine texture.

The green fronds have thin, soft blades with no hairs. The broad blades form a triangle shape. They are bipinnate to tripinnate, with two or three levels of division. Their pointed parts have toothed edges, which add to their finely divided look. The stout, smooth stalks range from pale green to dark red. The sterile blade lies almost flat. A fertile leaf grows before the sterile leaf. It bears groups of round sporangia, the sacs that hold spores. These groups look like a snake's rattle. This fern makes no flowers or fruit. NC State lists spores from September through November. New fronds rise straight, not from curled tips that unroll.

Grow it in partial to deep shade, in moist, fertile soil. It favors acid soil rich in decayed plant and animal matter. Sandy loam suits it, but water must drain well. NC State lists USDA zones 4–9. It suits woodland, native, and shade gardens. Deer tend to leave it alone. NC State reports no major pest or disease problems. Yet this fern is hard to get established in gardens. It needs soil fungi to live. Moves and splits often fail, so growers use spores instead.

People have gathered this fern for food and traditional medicine. Reports note that people boil it for food in the Himalayas. Which part they eat is unclear; one account suggests the root. Folk remedies use root preparations for skin wounds and lung complaints. These records do not prove that such treatments work or are safe. Sources report no known cases of poisoning from this species. They still urge care, since some ferns have harmful compounds. The evidence does not show that this fern is safe to eat.