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Lake Quillwort

Isoetes lacustris

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Plant Profile

Isoetaceae (Quillwort)
Also in this family:
Life Cycle:
Maximum Size:
20 centimetres tall
Bogs, fens, ponds, water, wetland.
Quillworts do not produce flowers. They reproduce by spores rather than flowers.
The female spores are about 0.5mm across. The male spores are microscopic so cannot be seen by the naked eye alone.
An underwater, clump-forming perennial plant. Its grass-like, cylindrical leaves are approximately 2mm wide. Similar in appearance to Spring Squillwort (Isoetes echinospora) but with darker leaves.
Other Names:
Common Quillwort, Merlin's Grass, Quillwort, Western Lake Quillwort.
Frequency (UK):

Similar Species

Other Information


Isoetes lacustris, commonly known as lake quillwort, is a species of aquatic plants in the family Isoetaceae. They are considered as one of the most ancient vascular plants in the world. The plants are known for their unique, spore-producing leaves that are arranged in a rosette, and the leaves are stiff, narrow and pointed. They are typically found in shallow water or on wet soils, and they can be found in a wide range of habitats, including bogs, fens, and vernal pools. They are also found in calcareous or acidic soils. They are generally considered as indicator species of good water quality, and they are often found in wetlands of high conservation value. They are also used for ornamental and educational purposes and for scientific studies. The lake quillwort is similar to Isoetes echinospora with the main difference is that Isoetes lacustris is often found in lakes and large ponds, while Isoetes echinospora is found in vernal pools and smaller bodies of water.


Lake Quillwort, or Isoetes lacustris, is a small, unassuming plant species that is found in freshwater lakes and ponds across the northern hemisphere. Despite its diminutive size and unassuming appearance, Lake Quillwort is an important ecological player in the aquatic ecosystems in which it is found. In this blog post, we will explore the unique characteristics of Lake Quillwort, its ecological role, and the threats that it faces in the modern world.

Physical Characteristics

Lake Quillwort is a small aquatic plant species that belongs to the genus Isoetes. It is characterized by its long, narrow leaves, which are arranged in a rosette pattern around a central stem. Each leaf is typically no more than a few centimeters long and is dark green in color. Lake Quillwort typically grows in water that is relatively shallow, with the tips of its leaves reaching just above the water's surface.

Ecological Role

Despite its small size, Lake Quillwort is an important ecological player in the aquatic ecosystems in which it is found. One of its most important roles is as a habitat for a wide variety of aquatic organisms, including insects, snails, and small fish. These organisms rely on the shelter provided by the dense growth of Lake Quillwort to protect them from predators and to provide a stable surface for their eggs and larvae.

In addition to its role as a habitat, Lake Quillwort also plays an important role in maintaining the health of the aquatic ecosystem in which it is found. Like all plants, it photosynthesizes and produces oxygen, which is essential for the survival of many aquatic organisms. Additionally, it absorbs nutrients from the water, helping to prevent the buildup of excess nutrients that can lead to harmful algal blooms.

Threats to Lake Quillwort

Despite its important ecological role, Lake Quillwort is facing a number of threats in the modern world. One of the biggest threats is habitat loss due to human development. As more and more lakes and ponds are filled in or drained for development, the habitats that Lake Quillwort and other aquatic species rely on are disappearing.

Another threat to Lake Quillwort is the introduction of non-native species. In some cases, non-native aquatic plants can outcompete native species like Lake Quillwort, reducing their populations and ultimately leading to their extinction. Additionally, non-native fish species can prey on the organisms that rely on Lake Quillwort for habitat, further reducing its ecological role.

Lake Quillwort, or Isoetes lacustris, is a small but ecologically important aquatic plant species. Despite its unassuming appearance, it plays a vital role in the health of the aquatic ecosystems in which it is found. However, it is facing a number of threats in the modern world, including habitat loss and the introduction of non-native species. To protect the important role that Lake Quillwort plays in our aquatic ecosystems, it is essential that we work to preserve its habitats and reduce the impact of human activities on our freshwater ecosystems.

More Information about Lake Quillwort

Lake Quillwort is an ancient plant species, with a lineage that dates back over 300 million years. Fossil evidence of Isoetes species has been found in sedimentary rocks from the Paleozoic Era, which is further evidence of the plant's resilience and adaptability.

One of the unique adaptations of Lake Quillwort is its ability to tolerate harsh environmental conditions. It can thrive in water with high levels of dissolved minerals, low oxygen levels, and even acidic conditions. This adaptability has allowed Lake Quillwort to survive and thrive in a wide variety of aquatic ecosystems, including lakes, ponds, and slow-moving streams.

Another interesting fact about Lake Quillwort is that it is a member of the ancient group of plants known as lycophytes. This group of plants includes a variety of ancient species, including clubmosses, spikemosses, and quillworts. Many lycophytes are extinct, but those that remain, including Lake Quillwort, provide a valuable link to the evolutionary history of the plant kingdom.

Lake Quillwort, or Isoetes lacustris, is a fascinating and ecologically important plant species that plays a vital role in our freshwater ecosystems. While it faces a number of threats in the modern world, there is much that we can do to help protect and preserve this ancient and resilient plant. By working to reduce our impact on freshwater habitats and by supporting conservation efforts, we can help ensure that Lake Quillwort and other important aquatic species continue to thrive for generations to come.

Lake Quillwort is not only an important ecological player in the aquatic ecosystem, but it also has cultural significance. For example, the indigenous peoples of North America have a long history of using Isoetes species for food and medicine. Some Native American tribes used Lake Quillwort as a food source, either by consuming the plant raw or by drying and grinding the roots to make flour. The plant was also used for its medicinal properties, as a treatment for a variety of ailments, including diarrhea and fever.

Lake Quillwort is also important for scientific research. Scientists have used the plant as a model organism to study a wide range of biological and ecological questions. For example, researchers have studied the plant's unique physiology, including its ability to photosynthesize under low light conditions, which could have important implications for developing new crop varieties that are more efficient in their use of light energy.

In recent years, there has been a growing interest in the use of Lake Quillwort and other aquatic plants for environmental restoration. Some researchers and conservationists believe that planting Lake Quillwort in degraded aquatic habitats can help restore the health of these ecosystems by improving water quality and providing habitat for a wide variety of aquatic organisms.

Overall, Lake Quillwort is a fascinating and important plant species that has played a vital role in the ecology and culture of the northern hemisphere for millions of years. By working to protect and preserve this unique plant, we can help ensure the health and vitality of our freshwater ecosystems for generations to come.

Distribution Map

Reproduced by kind permission of the BSBI.

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