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Sensitive Fern

Onoclea sinsibilis

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Plant Profile

Oncleaceae (Onocleoids)
Also in this family:
Life Cycle:
Maximum Size:
1 metre tall
Bogs, fields, marshes, meadows, riverbanks, swamps, waterside, wetland, woodland.
Flowers are absent on ferns. Instead, they reproduce using spores via a process called 'sporification'.
Spores exist on the erect, fertile stalks and are enclosed inside bead-like coverings.
A deciduous fern. Large, deeply pinnate. Each leaflet of the frond is untoothed and lanceolate to oblong. The fronds are sometimes called 'fiddleheads'.
Other Names:
Bead Fern.
Frequency (UK):

Other Information


Onoclea sensibilis, also known as sensitive fern or bead fern, is a large, terrestrial, rhizomatous fern in the family Onocleaceae. It is native to North America and Canada, and commonly found in moist woods, swamps, and along streams and rivers.

The plant has large, feathery, deciduous fronds that are typically 30-150 cm long and 10-40 cm wide, and are deeply lobed. The fronds are arranged in a rosette, and have a triangular shape. The fronds have a delicate and lacy appearance, with a midrib that is covered with large, bead-like spore cases.

O. sensibilis is commonly used as an ornamental plant in gardens and landscapes. It is well suited to moist, shady sites and tolerates a wide range of soil types. It can be propagated by spores or by dividing the rhizomes.

This fern species is not known to be invasive, and it is not considered to be a problem in gardens. However, in some areas, it can spread aggressively, which can be controlled by regular monitoring, removing any new growth, and also by using rhizome barriers.

Onoclea sensibilis has been used by indigenous people in North America for medicinal purposes such as for wound healing and as a pain reliever. However, there is little scientific evidence to support these uses, and more research is needed to confirm the plant's medicinal effects and determine appropriate dosage and usage.


Sensitive fern, also known as Onoclea sensibilis, is a fascinating and unique plant that can be found throughout much of North America. This fern gets its name from its remarkable ability to "sensitively" respond to changes in the environment, particularly changes in light and moisture.

Appearance and Characteristics

Sensitive ferns are deciduous ferns, meaning that they lose their fronds during the winter months. They typically grow to be about 2-3 feet tall and have fronds that are roughly triangular in shape. The fronds are a light green color and have a somewhat delicate appearance, giving the plant an overall soft and feathery look. The fronds are also quite large, with individual fronds growing up to 3 feet in length.

One of the most distinctive features of the sensitive fern is its spore-bearing structures, which are called sporangia. These are small, round, and arranged in clusters on the underside of the fronds. When mature, the sporangia will burst open, releasing spores into the air. This reproductive strategy is common to most ferns.

Growing and Habitat

Sensitive ferns are typically found in moist, shaded areas, such as the edges of woods, stream banks, and wet meadows. They prefer soils that are rich in organic matter and can tolerate a wide range of soil pH levels. They are relatively easy to grow and can be propagated from spores or by dividing existing plants.

Sensitivity to Light and Moisture

As mentioned earlier, sensitive ferns are named for their sensitivity to changes in light and moisture. When the fronds are exposed to bright sunlight or dry air, they will quickly curl up and wither, giving the appearance that the plant has died. However, this is actually a protective response that helps the plant conserve water and avoid damage from excessive light.

In addition to its sensitivity to light and moisture, the sensitive fern is also known for its ability to grow in areas that are prone to flooding. The plant is able to withstand flooding by sending up new fronds from underground stems, known as rhizomes. This allows the plant to survive even when its above-ground growth is temporarily submerged.

Uses and Benefits

Sensitive ferns have a few different uses and benefits. One is that they can be grown as an ornamental plant in gardens and landscaping, particularly in shady areas. They are also sometimes used in restoration projects to help stabilize stream banks and prevent erosion.

Another benefit of sensitive ferns is their value as a food source for wildlife. The plant is a host to the larvae of several butterfly and moth species, and its young fronds are eaten by deer, rabbits, and other herbivores.


Sensitive ferns are a unique and interesting plant species that is well-suited to wet, shaded environments. Their sensitivity to light and moisture makes them an excellent indicator of environmental conditions, and their ability to grow in areas prone to flooding makes them a valuable plant for restoration projects. Whether you're interested in growing them in your garden or simply observing them in their natural habitat, sensitive ferns are definitely worth learning more about.

More Information

In addition to their ornamental and ecological benefits, sensitive ferns have a number of other uses and cultural significance.

For example, some Indigenous peoples in North America have traditionally used the plant for medicinal purposes. The fern's rhizomes were boiled to make a tea that was believed to have a variety of healing properties, including as a treatment for fever and headaches. The plant was also sometimes used as a poultice for wounds or skin irritations.

Sensitive ferns are also sometimes used in horticulture to help remediate contaminated soils. The plant has been shown to have a high tolerance for heavy metals such as lead, and can help remove these contaminants from soil through a process called phytoremediation. This makes the fern a valuable tool for environmental cleanup efforts in areas that have been impacted by industrial pollution.

The sensitive fern is a fascinating plant with a variety of interesting traits and uses. Whether you're interested in their ecological, cultural, or horticultural significance, there is much to appreciate and explore about this unique fern species.

Another interesting aspect of sensitive ferns is their relationship with mycorrhizal fungi. Mycorrhizal fungi are a type of fungi that form a mutually beneficial relationship with the roots of many plant species, including sensitive ferns. The fungi help the fern absorb nutrients from the soil, while the fern provides the fungi with carbohydrates in exchange.

Some studies have found that sensitive ferns that are associated with mycorrhizal fungi are better able to tolerate drought and other stressors. This suggests that the relationship between the ferns and the fungi may be a key factor in the plant's ability to thrive in challenging environments.

Interestingly, sensitive ferns also have a unique way of reproducing asexually through a process called apogamy. Normally, ferns reproduce through spores, which are produced in the sporangia on the underside of the fronds. However, in apogamous reproduction, new ferns are produced directly from the cells of the parent plant, without the need for spores. This allows sensitive ferns to quickly spread and establish new colonies, and may be another adaptation that allows the plant to thrive in challenging environments.

Finally, it's worth noting that sensitive ferns are not the only species of fern that exhibit sensitivity to light and moisture. Other ferns, such as the maidenhair fern and the royal fern, also exhibit similar behaviors. However, the sensitivity of the sensitive fern is particularly pronounced, and has made it an interesting subject of study for scientists and nature enthusiasts alike.

Distribution Map

Reproduced by kind permission of the BSBI.

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