Aquatic Weed Guide
Aquatic Weed
Submerged and surface plant-life that can be found in deep and shallow waters
Canadian Pond-weed & Nuttals Water-weed
Elodea Family
Identification of Canadian Pond-weed
Freshwater herb, with much branched stems up to 3m long. The leaves are dark green and occur in whorls of three on the middle and terminal parts of the stem, becoming more crowded at the ends of the stem.
Identification of Nuttal's Water-weed
Similar to Canadian Pond-weed with long and slender stems, often freely branched. Leaves pale green more or less equally spaced along the stem middle and upper leaves typically in whorls of 3 or occasionally 4
Description
This incredibly invasive plant family are perrenial natives to North America. In the UK they grow quickly in shallow waters, easily out-competing native species, causing loss of biodiversity and choking up the water course. Despite being thought of as an 'oxengenating plant', large quantities can cause fluctuations in water-oxygen levels, harming fish and invertebrates. Both species are listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is also an offense to plant this species in the wild, demonstrating just how problematic this weed can be.
The scientific community seems to be in agreement that these species are best managed with a cut earlier in the year, around spring, to hamper new growth and stop excessive growth over the summer months. All cut vegetation should then be removed from the watercourse
Curly Water-weed
Lagarosiphon Major
Identification
At a glance could be seen as 'floating rope'. Curly Waterweed has branched stems and strongly curled leaves that alternate along the stem. Individual stems can grow up to 3m in length.
Description
This incredibly invasive plant is a native to South Africa that flourishes in UK waters. This species is similiar to that of the Elodea family in the way it quickly out-competes native species, causing loss of biodiversity and choking the water course if left untreated. Despite being thought of as an 'oxengenating plant', large quantities can cause fluctuations in water-oxygen levels, harming fish and invertebrates. There have been a number of cases of lagarosiphon completely filling even large bodies of water in the UK and Ireland.
As with Canadian Pond-weed and Nutall's Water-weed, Curly Water-weed is listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is also an offense to plant this species in the wild.
Broad-leaved Pond-weed
Potamogeton Natans
Identification
Leaves: Floating, dark green, leathery. 5 to 10 cm long, pointed at the tips, and rounded at the base
Flower: Dull yellow/green stalks, 5 to 10cm long
Description
A perennial plant that grows at a very fast rate and flowers between the months of May and September. Common in UK waters, this pond-weed grows in still freshwater such as lakes, pods and canals. It can grow up from 1 to 2 metres but especially common in water less than a meter deep.
Duck Weed
Lemnoideae
Identification
Leaves: Individual plant diameter: 1.5-5mm. Many of these tiny plants are packed closely together to create a yellow-green 'lawn' across the water's surface
Description
A familiar sight of freshwater ponds, flooded gravel pits and old canals, Common Duckweed multiplies by division and can easily form a vast mat that overtakes the surface of the watercourse if left unchecked. Due to the size of the individual plants conventional methods and hand clearing can prove nearly impossible
At Aquaclear, we make use of the Truxor's unique toolkit to scoop this weed out of the water and deposit it on the banks
Water Soldier
Stratiotes Aloides
Identification
Leaves: Rosettes of sword-shaped serrated leaves coming from a single a point held on long thin strands from the water-bed
Flower: Single, 3 petaled white (sometimes pinkish) flower held above water in summer
Description
Native to Europe these plants grow beneath the water, staying submerged for most of the year. From June to August, they surface and flower, displaying white blooms. Manageable in small amounts but in large amounts can quickly choke small water courses
White & Yellow Water Lily
Nymphaea alba & Nuphar lutea
Identification of White Water Lily
Flower: Large, white flowers that are sometimes tinged with pink and are borne on stalks just above the water
Leaves: Familiar rounded, leathery, lily-pad leaves that are up to 30cm across on stalks resting on the water surface
Identification of Yellow Water Lily
Flower: Smaller, cupped, yellow flower
Leaves: More oval leaves than the White-water Lily, and generally smaller
Description
Common throughout UK waters this plant grows in water up to 5m deep, with the flowers and leaves floating on the surface of the water. It flowers during the summer,
from June to August, with blooms opening up in the sunshine. Although Lilies are often a welcome addition to water courses, excessive growth can prove problematic as
they can cover large portions of the water's surface with their dense leaves, hampering the growth of other plant species. In such cases it may be necessary to cut back
portions of the plant yearly to maintain a healthy balance, or in more severe cases, remove the rhizomes completely
Algae
Identification of Algae
Algae appears as a foam, scum, or mat on or just below the surface of water and can take on various colors depending on their pigments. Generally, in UK waters,
you can expect algae to be a bright green to yellowish colour and may resemble a 'paint spill' on the surface of the water
Description
Algal blooms arise as a result of an overabundance of nutrients in the water, which can be a result of urban or agricultural run off, combined with
high water temperatures and still or standing water. In recent years, the UK (and the rest of the world) has seen an increase in Algal blooms which many experts attribute
to rising temperatures. Unfortunately, this is bad news for our
water courses as these blooms are not just unsightly and odorous, but can also be incredibly damaging to the watercourse and the animal and plant species within it.
HABs
Harmful Algal blooms or HABs, make the news yearly in the form of 'blue-green algae' and are virtually indistinguishable from non-toxic blooms (the algae itself needs
to be sampled and tested in order to prove the existence of toxins). HABs can cause a wide
range of issues, from using up all the oxygen in the water, resulting in fish and plant-life die-off, to producing toxins that can harm and even kill animals that come into contact with it
Non-Toxic Blooms
Non-toxic blooms are not without their own issues however, as large blooms block light from reaching deeper parts of the watercourse and increase the pH of the water,
disrupting the balance of the watercourse and causing massive fish and plant-life die-offs if left untreated. When these blooms eventually die themselves over the colder months,
the microbes that decompose the blooms eat up oxygen, disrupting the balance of the watercourse further. Unfortunately, if left untreated, algal blooms can get bigger year
after year
If you are experiencing any issues with Algae on your own watercourse, there are a number of options available to you in order to control its growth, ranging from simple
removal, to increasing movement and flow of the water, to the introduction of barley-straw rafts which have shown to slow algal growth. Please contact us to discuss
which methods are best suited to your water course.
In the Margins
Emergent plant-life that can commonly be found in the margins and very shallow waters of a watercourse
Branched & Unbranched Bur-Reeds
Sparganium Family
Identification of Branched Bur-Read (top image)
Leaves: Medium to tall robust erect plant up to 1.5m in height. The leaves are long green spikes and usually erect but occasionally they lie floating on the surface of the water
Flowers: Produces branched stems with greenish-white male and female flowers in separate clusters, followed by prickly green, then brown fruit up to 1cm across
Identification of Unbranched Bur-Read (bottom image)
Leaves: Grows in deeper water than Branched Bur-reed. It has narrower leaves which float on the water surface
Flowers: Unbranched Bur-reed has similar flowers to Branched Bur-reed but in a single, unbranched spike
Description
The Sparganium family of plants are extremely common in UK waters, finding a home along lakes, ponds, canals and just about any other water course. The Branched Bur Reed can be found in very shallow waters and in the margins, with the Unbranched Bur Reed being found in slightly deeper waters of up to 1m deep. Both plants have densly inter-woven rhizomes that can cause 'mats' of silty root-matter below the waters surface.
Excessive growth can quickly choke water courses and cause issues with water flow and overall depth. This means your watercourse may need frequent cutting or the removal of the rhizomes altogether via excavation
Bulrush/Cattail
Typha
Identification
Can grow up to 3m tall with long bladed leaves. Has a single, thin, straw coloured spike as a stem with the familiar brown 'sausage' shaped flower at the top
Description
A common feature in UK waterways, Bulrush can be found in or beside fresh water where soil is rich, often growing with Common Reed. In the right conditions this plant can become invasive, quickly choking the watercourse from the banks inwards. Cutting or removal of root matter via excavation can easily curb any excessive growth
Common Reed
Phragmites
Identification
The Common Reed forms large beds; it has round, hollow stems, which typically grow to 2 metres in height, but may reach 4 metres. The flat leaves taper into a point, and are attached to the stem by smooth sheaths. The flowers, which measure from 20 to 60 cm in length are grouped into 'spikelets', which are 10-15 mm in length and support 1 to 6 flowers
Description
Common Reed forms extensive, yellow-brown reedbeds in wetlands across the UK (but not uncommon along lakes and canals), greening over in the summer months with the new growth. These reedbeds are important habitats for birds and other wildlife. Common Reed grows from creeping rhizomes and flowers from August to October.
Reed beds are considered 'temporary habitats' as they are the intermediary stage of a habitat as it moves from wet, open water, towards dryer marshier land. As such, they require a lot of maintenance to ensure this balance between wet and dry is kept, and wildlife are encouraged to return year after year
You can find out more about our work with reed beds on our
Reed Bed Management page.
Floating Pennywort
Hydrocotyle ranunculoides
Identification
Leaves: Water pennywort has stems that spread horizontally and can float on water. Leaves grow on petioles up to 35 cm long, and are round to kidney-shaped, with 3–7 lobes and crenate to entire margins
Flowers: Flowers are small, pale greenish white to pale yellow, and come in umbels of 5–13
Description
A very invasive species to the UK that grows in shallow margins and protrudes out from the bank into deeper water. It is currently spreading at an alarming rate in UK waterways and in 2014 it was one of five aquatic plants which were banned from sale in the UK, the first prohibition of its kind. Removal of this weed from the watercourse is essential to curb growth
Mare's-Tail
Hippuris Vulgaris
Identification
Leaves: Occur in whorls of 6-12; those above water are 0.5 to 2.5 cm long and up to 3 mm wide, whereas those under water are thinner and limper, and longer than those above water.
Stems: Solid and unbranched but often curve, and can be up to 60 cm long. In shallow water they project 20–30 cm out of the water
Description
The common mare's tail is a creeping, perennial herb, found in shallow waters and mud flats. It roots underwater, but most of its leaves are above the water surface. Studies have shown it to be prolific methane emitter and in large quantities can become troublesome, obstructing the flow of streams and rivers
Horsetail/Snake Grass
Equisetum sp.
Identification
Leaves: Thin and spiky, arranged in whorls from the central ridges
Stems: The stems are usually green, jointed and ridged (usually 6–40 ridges). There may or may not be whorls of branches at the ridges.
Description
Superficially similar but entirely unrelated to mare's tail (Hippuris), this weed is common in very shallow waters and in the margins of watercourses. If left this weed can spread very quickly and become unsightly. In more severe cases, it can grow throughout the watercourse and hamper the growth of other plant species
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