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Limestone Fern

Gymnocarpium robertianum

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Contents

Plant Profile

Order:
Polypodiales
Family:
Cystopteridaceae (Bladder Fern)
Type:
Fern
Life Cycle:
Perennial
Maximum Size:
40 centimetres tall
Habitats:
Gardens, riversides, rocky places, waterside, woodland.
Flower:
No flowers. Ferns produce spores instead in order to reproduce.
Fruit:
The spores ripen in July and August.
Leaves:
The fronds appear from May to September. Similar to Northern Oak Fern (Gymnocarpium dryopteris) but is taller and more erect. It has larger fronds which are a duller shade of green.
Aroma:
The fronds are fragrant after bruising.
Other Names:
Limestone Oak Fern, Northern Oak Fern, Robert's Wood Fern, Rock Tripe, Scented Oak Fern.
Frequency (UK):
Unusual  

Similar Species

Other Information

Summary

Gymnocarpium robertianum, also known as Robert's wood fern or rock tripe, is a small fern that is native to North America and Europe. It is a perennial fern that typically grows to be about 6-8 inches tall and wide. The fronds of G. robertianum are deciduous, which means they die back in fall and grow again in spring, and are about 6-8 inches long and 3-4 inches wide. They are compound and feathery, with a long central stem that has many leaflets or pinnae, which are further divided into smaller segments or pinnules. The leaves are green and glossy on the upper surface and paler on the underside.

The Robert's wood fern prefers moist, well-drained soils and partial to full shade, and it is commonly found in woodlands, along streams and rivers, and in rocky or sandy areas. It is also found growing in mossy crevices, and on rocky outcrops, ledges and talus slopes. It is an important food source for several species of wildlife. It is also a popular ornamental plant due to its attractive foliage, and it can be grown in gardens, along borders, or as a ground cover.

This fern is hardy in USDA zones 4-8, and can handle some sun exposure in cooler climates, and is relatively easy to grow if given suitable conditions. G. robertianum is a widely distributed and common fern, not considered as threatened species and it is commonly available commercially.


Blog

Limestone Oak Fern (Gymnocarpium robertianum) is a small but attractive fern species that belongs to the family of wood ferns (Dryopteridaceae). The plant is native to Europe and can be found in many parts of the continent, particularly in limestone areas. The species is also known by several other common names, including limestone fern, oak fern, and rock fern.

Physical Description

Limestone Oak Fern is a small fern that usually grows to a height of 20-40cm. It has a slender and erect rhizome, with short, dark-brown scales at its base. The fronds are light green in color and are bipinnate, meaning that each leaf is divided into several leaflets, which are further divided into smaller leaflets. The leaflets are attached to the stem by a slender stalk, and each has a delicate texture, which gives the plant a soft, lacy appearance.

Habitat and Distribution

Limestone Oak Fern is primarily found in limestone areas and rocky outcrops, where it grows in a variety of habitats, including woodlands, meadows, and hillsides. The plant is also found in other areas with well-drained soil and moderate moisture, such as the edges of streams and springs.

The species is native to Europe, and its range extends from Portugal in the west to the Caucasus Mountains in the east. The plant can also be found in northern Africa and the Middle East.

Ecological Importance

Limestone Oak Fern is an important species in the ecology of limestone habitats. It is an indicator of alkaline soils, and its presence often signals the presence of other rare plant species in the area. The fern provides habitat and food for a variety of small animals, including insects and snails. It is also an attractive ornamental plant that is grown in gardens and rockeries.

Conservation Status

Limestone Oak Fern is considered a species of conservation concern in many European countries due to its restricted distribution and habitat loss. The plant is threatened by urbanization, agriculture, and quarrying, which have led to the destruction of its limestone habitat. In some areas, the plant has also been over-collected for horticultural purposes. As a result, the species is protected under national and international conservation laws.

Conclusion

Limestone Oak Fern is a small but important fern species that is found in limestone habitats across Europe. It is an indicator of alkaline soils and provides habitat and food for a variety of small animals. The plant is threatened by habitat loss and over-collection and is protected under national and international conservation laws. Efforts are needed to conserve the species and its habitat to ensure its survival for future generations.


Facts about Limestone Oak Fern

Here are some additional interesting facts about Limestone Oak Fern:

  • The Latin name for the species, Gymnocarpium robertianum, was given in honor of the Scottish botanist James Robertson, who discovered the plant in the early 1800s.
  • Limestone Oak Fern is a deciduous species, meaning that it sheds its leaves in the fall and regrows them in the spring.
  • The fern's fronds are said to resemble the leaves of an oak tree, hence the common name "Oak Fern."
  • Limestone Oak Fern can reproduce both sexually (through spores) and asexually (through rhizomes).
  • In some parts of Europe, Limestone Oak Fern has been traditionally used for medicinal purposes, such as treating wounds and diarrhea.
  • The fern has a delicate, almost feathery appearance that makes it a popular ornamental plant for rock gardens and shady areas. However, it can be challenging to cultivate, as it requires well-draining soil and consistent moisture.
  • Limestone Oak Fern is a food source for the larvae of several butterfly and moth species, including the Duke of Burgundy butterfly and the Pearl-bordered Fritillary butterfly.
  • The fern's distribution range is limited to Europe, northern Africa, and the Middle East, but it has been introduced to some parts of North America and is considered an invasive species in certain areas.
  • Limestone Oak Fern is protected under the Convention on the Conservation of European Wildlife and Natural Habitats (also known as the Bern Convention), as well as national laws in several European countries. Conservation efforts include habitat restoration and protection, as well as regulation of horticultural trade.

Blog continued...

Limestone Oak Fern, Gymnocarpium robertianum, is a small fern species that grows in limestone areas and rocky outcrops across Europe. The plant has a slender and erect rhizome and light green, lacy fronds that are bipinnate, with each leaf divided into several leaflets that are further divided into smaller leaflets.

The species provides habitat and food for a variety of small animals, including insects and snails, and is an important indicator of alkaline soils in its ecosystem. Limestone Oak Fern is also an attractive ornamental plant that is grown in gardens and rockeries.

However, Limestone Oak Fern is considered a species of conservation concern in many European countries due to its restricted distribution and habitat loss. The fern is threatened by urbanization, agriculture, and quarrying, which have led to the destruction of its limestone habitat. In some areas, the plant has also been over-collected for horticultural purposes. As a result, the species is protected under national and international conservation laws, including the Bern Convention.

Conservation efforts for Limestone Oak Fern include habitat restoration and protection, as well as regulation of horticultural trade. These efforts are important to ensure the survival of the species and its ecosystem for future generations.


Video

Limestone Fern filmed at Scout Scar, Cumbria on the 26th May 2023:

 

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Distribution Map

Reproduced by kind permission of the BSBI.

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