The Sensitive fern (Onoclea sensibilis), also known as the Bead fern, is a coarse-textured, medium to large-sized perennial fern. The name comes from the observation by early American settlers that it was very sensitive to frost, the fronds dying quickly when first touched by it. It is the sole species in the monotypic genus Onoclea.
The sterile and fertile fronds of this fern are quite different. The bright, yellow-green sterile fronds are deeply pinnatifid and are typically borne at intervals along a creeping rhizome. They grow to about 90 cm long, with a long, smooth stipe. The fertile fronds are much smaller, non-green, and have very narrow pinnae. The sori are clustered like beads or grapes on the upright fertile fronds, hence the common name Bead fern. The fiddleheads are a pale red color.
This fern dwells in a variety of wet swamp and wood habitats: wet meadows, thickets and bogs, as well as stream and riverbanks and roadside ditches. It ranges from Newfoundland to Florida and west to Texas, North Dakota and Manitoba, but is also native to east Asia and has become naturalized in western Europe.
It grows best in a shaded or partially shaded area in a moist soil. The plant will tolerate wet soils and so can be used near water. Winter survival will be enhanced if the dried fronds are left on the plant through the winter. Sensitive ferns spread to form colonies and are often the first species to inhabit disturbed areas. They can become weedy if not sited properly. In shade it can tolerate dryer conditions, but if grown in full sun it practically needs to be soggy ground or the very edge of water.