Rattlesnake Fern Botrychium virginianum

Rattlesnake Fern is a deciduous fern that is found in a wide variety of climates. They may be found in dry, mesic, and wet forests. They may also be found in coves, moist bottomlands, and slopes. This plant prefers moist rich woods and shade. It is one of the first ferns to begin growth in spring. It has subterranean rhizomes and horizontal, coarse, shallow roots. It produces distinctive spores that rise at the conjunction of the leaves. It is a member of the Ophioglossaceae or Adder's Tongue family of ferns.

The Rattlesnake Fern is native to most of North America, Central America, portions of South America, Eurasia, China, Korea, and Japan. It is the most widespread of the ferns in this genus in North America. 

The genus name, Botrychium, is Greek in origin for botrys, which means a "bunch of grapes." This references the sporangia, which are spore-bearing organs of this plant. The common name, Rattlesnake Fern, refers to the clusters of sporangia that resemble a snake "rattle."

The Rattlesnake Ferns prefers partial to light shade and moist fertile soils. They thrive in an abundance of decaying organic matter and are best suited for acidic soils. They are dependent on fungi in the soil to survive. This plant is difficult to cultivate. Dividing or transplanting is usually unsuccessful. They are propagated by the germination of their spores.

The plant may grow from 1 foot to 4 feet at maturity. The root system consists of fibrous rhizomes. The leaves of the Rattlesnake Fern are light green, and the stalks are light green to red. The plant consists of a single sterile leaf and a second fertile leaf. The fertile leaf develops before the sterile leaf. The sterile leaf measures 4-8 inches long and 5-10 inches across and is positioned horizontally with the ground. It is pinnately divided into 5-12 pairs of leaflets. Each leaflet is pinnately divided into up to 12 sub-leaflets. The sub-leaflets are ovate, lanceolate, or oblong in shape and have coarse dentate margins. The fertile leaf is 3-6 inches long and about 1.5 to 3 inches across. Its leaflets and sub-leaflets are stalk-like in appearance. The sporangia are attached to the leaflets and sub-leaflets of the fertile leaf. Once the sporangia mature, the spores are released and distributed by the wind. The plant has no flowers or fruits.

Rattlesnake Fern and the Cutleaf Grape Fern are very similar in appearance and habitat. The fronds of the Cutleaf Grape Fern are leathery; whereas, the Rattlesnake Fern fronds are thin, non-leathery, and delicate. The Cutleaf Grape Fern is evergreen, and the Rattlesnake Fern is deciduous.

VIDEO Created by NC State Extension's Homegrown series featuring Mark Weathington, Director of JC Raulston Arboretum.