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Water Lobelia

Lobelia dortmanna

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
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Plant Profile

Flowering Months:
Campanulaceae (Bellflower)
Life Cycle:
Maximum Size:
90 centimetres tall
Gardens, mountains, riversides, water, waterside, wetland.

Purple, 5 petals
Pale lilac-coloured flowers. 2 lipped. 1 to 2cm in length. 5 stamens.
Slightly flat capsule with a rounded base and pointed at the tip.
The leaves are always submerged. They appear in basal rosettes and are untoothed and linear. Perennial.
Other Names:
Dortmann’s Cardinalflower, Dortmann's Lobelia.
Frequency (UK):

Other Information


Lobelia dortmanna is a species of perennial herb that is native to Europe and Asia, it is also known as Dortmann's lobelia or water lobelia. It is known for its small, blue, white or pink, trumpet-shaped flowers that bloom in the summer and fall. The plant has basal leaves that are lanceolate, and the stem leaves are smaller. It prefers moist soils and full sun to partial shade, it can be found growing along the edges of ponds, streams, and other wetland habitats. It is often used as an ornamental plant in gardens and is also used in cut flower arrangements and as a water plant in aquaria.


Water lobelia (Lobelia dortmanna) is a unique and fascinating aquatic plant that is found in freshwater habitats such as lakes, ponds, and slow-moving streams. It is a member of the Campanulaceae family and is native to the Northern Hemisphere, including Europe, Asia, and North America. Water lobelia is commonly known by several names, including water lobelia, water lobelia, and dortmann's cardinal flower.

Water lobelia is a perennial plant that grows in shallow waters, typically less than three feet deep. It has a slender, unbranched stem that grows up to two feet tall and is covered in small, dark green leaves that are about an inch long. The leaves are submerged in water and grow in a spiral pattern around the stem. The stem also bears small, inconspicuous flowers that are about a quarter-inch wide and are greenish-yellow in color. The flowers bloom in mid to late summer and are pollinated by bees and other insects.

One of the unique features of water lobelia is its specialized root system. Unlike most plants, water lobelia does not have traditional roots that anchor it to the soil. Instead, it has thin, fibrous roots that are covered in tiny, hair-like structures called root hairs. These root hairs absorb nutrients and oxygen from the water and anchor the plant in place. Water lobelia can also reproduce by producing small, black seeds that float on the surface of the water.

Water lobelia plays an important role in freshwater ecosystems. It provides habitat and food for a variety of aquatic insects, fish, and other animals. It also helps to maintain water quality by absorbing excess nutrients and reducing sedimentation. In addition, water lobelia is an indicator species, meaning that its presence or absence can indicate the overall health of a freshwater ecosystem. If water lobelia is absent or in decline, it may be a sign of pollution or other environmental stressors.

Despite its importance, water lobelia is considered a threatened species in many parts of its range. Habitat loss, pollution, and invasive species are all major threats to water lobelia populations. To protect water lobelia and other aquatic plants, it is important to conserve freshwater habitats, reduce pollution, and prevent the spread of invasive species.

Water lobelia has also been used for various medicinal purposes. Historically, it was used by Native Americans to treat a variety of ailments, including headaches, fevers, and respiratory issues. The plant contains several chemical compounds, including lobeline, which has been shown to have anti-inflammatory and analgesic properties. However, it is important to note that the plant can be toxic in large quantities and should not be consumed without proper guidance from a healthcare professional.

In addition to its ecological and medicinal significance, water lobelia is also a popular plant in aquatic gardens and water features. Its unique appearance and ability to thrive in shallow waters make it a popular choice for creating natural-looking water gardens. Water lobelia can be grown in containers or directly in the water, and it prefers full sun to partial shade.

Water lobelia is not only important for its ecological and ornamental values, but it also has potential applications in phytoremediation, which is the use of plants to remove pollutants from soil and water. The plant's fibrous roots and ability to absorb excess nutrients make it a potential candidate for use in treating contaminated water sources.

Water lobelia is also a food source for a variety of aquatic animals, including waterfowl and fish. Ducks and geese are known to feed on the plant's leaves and stems, while fish consume the seeds and small invertebrates that live among the plant's roots. This makes water lobelia an important part of the food web in freshwater ecosystems.

Conservation efforts for water lobelia include protecting its natural habitats, such as lakes and ponds, from pollution and development. Additionally, efforts are being made to propagate the plant in nurseries and reintroduce it to areas where it has been lost or is declining.

Water lobelia is also known to have cultural significance. In Finnish folklore, the plant was believed to have magical properties and was used in healing rituals. The plant was also used in traditional Finnish medicine to treat a variety of ailments, including toothaches, headaches, and respiratory issues.

In addition, water lobelia has been used in scientific research to study the effects of climate change on aquatic ecosystems. Scientists have used the plant as a model organism to investigate how rising temperatures and changes in water chemistry may affect the growth and survival of aquatic plants.

Water lobelia is a sensitive species that can be negatively impacted by changes in its environment, including pollution, invasive species, and climate change. It is important to continue monitoring water lobelia populations and take action to protect the species and its habitat.

Overall, water lobelia is a fascinating and valuable plant that is worthy of our attention and protection. Its unique features, ecological significance, cultural and medicinal uses, and potential applications in research and phytoremediation make it a valuable species to study and conserve. By taking steps to protect water lobelia and its habitat, we can help ensure the continued survival of this important aquatic plant.

Distribution Map

Reproduced by kind permission of the BSBI.

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