Species

Here you will find a simple illustrated identification guide for small animals that you can find in the water. A large part of the larval stages of various insects, but also crayfish such as the waterlouse are described. Also look for the notes of distinguishing characteristics or possibilities of confusion (black diamond). The table is originally from GLOBE Swiss and has been modified and extended.  

Chart for an overview of insect larvae living underwater   CADDISFLIES (TRICHOPTERA)  The caddisfly larvae are of great importance for a water body. They can be divided into two groups. The caddisless larvae and the caddis-bearing larvae. The quiver-bearing larvae build their caddis from their own produced spider silk and incorporate various materials from their habitat into it. The material is extremely diverse and can be constructed from grains of sand, sticks, shells, spruce needles, or pieces of leaves. It serves to protect the larvae and is their home that they constantly carry around. The caddis is always expanded by the growing larva. In fast flowing streams heavy material is often used such as stones or sand. Caddisless larvae usually live in waters with enough current to keep their (tracheal) gills well supplied with oxygen. They look caterpillar-like and spin a kind of funnel into the current, in which microorganisms, algae or dead plant material collects which serves as food for them. Some caddisless larvae are also active hunters. Caddisfly larvae are only able to survive in clean or slightly polluted waters. They can often be found in groups under stones. The adult caddisflies are unimpressive, gray-brown flying insects that hide during the day in moss and deadwood or under leaves of plants near the shore. Towards evening they dance in swarms at the water's edge and are then often mistaken for mosquitoes or moths. Unlike moths, however, they carry their antennae long and pointing forward.   A accumulation of caddisflies under a stone of a stream in Rhineland-Palatinate, Germany   Photo from GLOBE Swiss     Example of a caddisless larva and a caddis-bearing larva. Drawings from Kosmos Publishing House       An adult caddisfly, it is usually grayish brown in color and inconspicuous. Drawing from Kosmos Publishing House…

CRUSTACEANS (CRUSTACEA)   The water louse (Asellus aquaticus), a commonly encountered species. Photos: Kosmos Publishing House and GLOBE Swiss Most crayfish species live in the sea, but there are also some representatives in fresh waters. Frequently encountered crayfish species in our waters are rather the small, often only up to 20 mm in size and with an articulated carapace (Peracarida). These include the water louse (Asselus aquaticus), which is found in slow-flowing and stagnant waters. It has no great demands on water quality and lives among foliage and dead plant debris. Aquatic isopods eat detritus and play an important role in decomposing foliage. Woodlice are often grayish brown, sometimes purple in color. Unlike the freshwater amphipod, it crawls over the ground and does not curl its body.   The freshwater amphipod (Gammarus pulex) lives as its name indicates in streams, there is also an amphibod species that lives more in lakes (Gammarus lacustris). The body is quite light and lies on its side in resting position and is usually curved. The amphipods colonize all types of water, but the oxygen and calcium content must not be too low. The name refers to the dynamic swimming movement of the amphipods. Freshwater amphipods also decompose dead plant material, but sometimes they eat mosquito larvae. They also provide an important food source for predatory fish. Native decapods like the European crayfish (Astacus astacus) are almost non-existent, they have almost all been replaced by the invasivedecapod species. See the Signal Crab or theCamber crab. "File:Astacus astacus in danger.jpg" by brian.gratwicke is licensed under CC BY 2.0.    THE SURGERY (MOLLUSCA) - Mussels and snails Bivalves and snails both form a shell in which they live, they have either a muscular adhesive foot (bivalves) or a foot with a creeping sole (snails) over which they move…

Where? The brooklime is found in ditches, springs and streams, also on the shores of lakes and ponds, and prefers cool waters. Appearance? European speedwell or brooklime is a perennial herbaceous plant that reaches growth heights of 30 to 60 cm. Fleshy, hollow stems grow from the creeping rhizome, from which elliptical, fleshy leaves with serrated leaf margins grow, blunt at the front. The racemose inflorescences arise from the leaf axils and contain 20 -25 flowers with sky-blue corollas with a diameter of 5 - 8 mm. Special features? As a salad, the fresh stems and leaves are considered digestive, they contain a lot of vitamin C and can also be cooked into a (bitter) vegetable.     "Veronica beccabunga, Cresson de cheval" by Jean Guérin is licensed under CC BY-NC-SA 2.0   "Veronica beccabunga 2017-06-06 2905" by Salicyna is licensed under CC BY-SA 4.0

Where? The Water silk is a grren algae, it grows best in nutrient-enriched (eutrophic), clear and calm waters. The green alga is found only in ecologically disturbed waters and indicates poor condition of the water body. Appearance? Filamentous, free floating, light green slimy patches. Special Features? With enough sunlight and warmth, small bubbles form and the algae rise to the water surface. "Spirogyra" by Dr Mary Gillham Archive Project is licensed under CC BY 2.0   "SpirogyraIreland" by Notafly is licensed under CC BY-SA 4.0

Where? Curly pondweed grows best in nutrient-polluted (hypertrophic), slow-moving to stagnant waters. It is typical of waters in intensively managed areas. Appearance? Curly pondweed is a perennial, winter and deciduous herbaceous plant, with light to olive green leaves in summer that turn brownish in winter. It grows anchored to the bottom of the water with leaves that are wavy at the edges and distinctly toothed. The toothed leaves are a distinct identifying characteristic of Potamogeton crispus. Special features? Flower spikes up to 2 cm long form on the water surface from June to August. The overwintering form benefits the spread of the pondweed.     "Potamogeton crispus 5447254" by Nonemac is licensed under CC BY 3.0     Easy to recognize: The toothed leaves of Potamogeton crispus Kristian Peters -- Fabelfroh 14:40, 29 December 2005 (UTC), CC BY-SA 3.0, via Wikimedia Commons   Form of preservation, which sinks to the bottom of the water in winter, this is also a vegetative possibility of spreading. Kristian Peters -- Fabelfroh 13:07, 10 October 2006 (UTC), CC BY-SA 3.0 , via Wikimedia Commons

Where? Stoneworts require clean, nutrient-poor and calcareous water. They are found in both standing and flowing waters. Appearance? Stoneworts (Charophyceae) are a form-rich class of green algae with over 70 different species. Chara vulgaris & Nitella flexilis are the most represented. They form shoots up to 60 cm long with numerous side shoots up to 1 mm thick, on which pinnate branches of 5 or 7 are in whorls. Particular are the unbarked terminal limbs of the branches and the brown/grey and orange reproductive cells below the whorls. Special features? Stoneworts can colonize freshly formed water bodies and water accumulations as a pioneer plant. When removed from the water, the alga often develops a specific odor, which is said to resemble mustard oil.   "Characeae 041205-3537" by Toni Rodd is licensed under CC BY-NC-SA 2.0   "CharaGlobularis" by Christian Fischer is licensed under CC BY-SA 3.0

Wood club-rush (Scripus) is a genus of grass-like species in the sedge family. Where? Nutrient-rich, loamy-humic and slightly acidic substrate is ideal for most species. However, they are considered natural inhabitants of riverbanks or wetlands. Appearance? The species grow as perennial herbaceous plants, reaching growth heights of 30 to 200 cm, depending on the species. Some species form rhizomes (roots). The culms are solitary to many together. The culms are usually triangular and the leaves are grassy.   The wood clubrush (Scirpus sylvaticus) colonizes nutrient-rich swamps and fens, swelly clay soils, wet meadows and ditch margins, as well as riparian and marsh forests. In wet litter meadows it settles in the wettest places - it is therefore a wetness indicator. "Scirpus sylvaticus RF" by Robert Flogaus-Faust is licensed under CC BY 4.0.   Another species - Scirpus lacustris that also grows in water , its culms have "air tubes" through which it directs air into the roots growing underwater. “Scirpus lacustris — Flora Batava — Volume v9.jpg” is licensed under Public domain

Where? The Sago pondweed can be found in many water types and is indifferent for the waterquality and belong to the flloating leaf water plants. It occurs in oligo- (low nutrient content) as well as in eutrophic, slow flowing or still waters. It grows mostly on humic soils and requires water depths of 20 to 350 cm. Appearance? It is a permanently submerged, deciduous, highly branched plant with limp, filamentous leaves that grow up to 3 mm thick. Special Features? The plant forms 2-5 cm long spikey flowers from May to September. The waterplant may also be known from the synonym Stuckenia pectinata.   "Potamogeton pectinatus fruits. Cadoxton Pool, August 1979" by Dr Mary Gillham Archive Project is licensed under CC BY 2.0

Where? Grows in swamps, on banks and frequently shallow flooded sites, requires constantly moist soils. Appearance? Perennial, cryptophyte plant. Smooth stem with growth height between 30 and 120 cm, with filamentous shoots at regular intervals, which are formed for reproduction. From May to June, an egg-shaped spore ear forms at the top of the horsetail.. Special Features? May be toxic to cattle, easily confused with marsh and field horsetail, Water horsetail hybridizes with field horsetail to form the so-called Equisetum × litorale. The Water horsetail is hollow.   "EquisetumFluviatile" by Christian Fischer is licensed under CC BY-SA 3.0

Where? Water blinks (Montia fontana) is a marsh plant found in streams, ditches, and wet fields worldwide. It thrives best in nutrient-poor soils. Appearance? Water blinks grows as an annual to perennial herbaceous plant and reaches growth heights up to 30cm, often found in mat-like stands. Stems grow decumbent to erect and sometimes float in water. Foliage leaves grow opposite in lanceolate shape with length from 3 to 20mm. In the flowering period from June to August, racemose inflorescences with up to eight flowers are formed. The flowers are radially symmetrical, with white petals and up to 3 mm in diameter Special features? The capsule fruits are self-propagating by rolling up the three fruit flaps and then catapulting the seeds out to a distance of 2 meters and a height of 0.6 meters.   "Blinks (Montia fontana)" by --Tico-- is licensed under CC BY-NC-ND 2.0   "6814123" by Alex Abair is licensed under CC BY-NC 4.0

Where? Duckweed grows on sunny, stagnant to slow-flowing and nutrient-rich (eutrophic) to polluted (hypertrophic) waters. Appearance? Free floating plant on the water or just below the water surface, with one or more small green leaves, with diameters of 3-6 mm. A short root filament grows into the water, for mineral absorption.  Special Features? Gibbous duckweed (Lemna gibba), common duckweed (Lemna minor) and least duckweed (Lemna minuta) are difficult to distinguish from each other and often occur together. Duckweed often covers entire bodies of water, which prevents submerged plants from growing and can also affect water temperature.   "Klein kroos Lemna minor" by Rasbak is licensed under CC BY-SA 3.0   "Lemna minor Subaquatic view Lamiot 11" by Lamiot is licensed under CC BY-SA 4.0

Where? The hornwort grows best in nutrient-rich (eutrophic), stagnant to slow-flowing and summer-warm waters, with humus-rich muddy soils in water depths of 0.5 to 10 meters. Appearance? Submerged living plant with often reddish stems between 30 and 100cm long. Dark green, once, or twice branched, rigid leaves, arranged radially at regular intervals around the stem. Special Features? Rare, inconspicuous flowers up to 3mm long, between July and September. Its dense growth can outcompete native underwater vegetation, leading to loss of biodiversity.   "Ceratophyllum demersum 240907a" by Bernd Haynold is licensed under CC BY-SA 3.0   "Ceratophyllum demersum (inflorescence)" by Christian Fischer is licensed under CC BY-SA 3.0

Where? The Bog stitchwort (Stellaria alsine) typically grows on wet sites, along spring edges, forest roads and ditches on seepage-wet, more or less nutrient-rich soils in partial shade. Appearance? The brook chickweed is a perennial herbaceous plant that reaches growth heights or lengths of 10-40 cm. The leaves are directly on the stem or short stalked, elongated pointed and bluish green color. In the flowering period from May to July it forms small radiating white to light green flowers   "Stellaria alsine kz12" is licensend under CC BY-SA 4.0   "Stellaria alsine sl17" by Stefan.lefnaer is licensend under CC BY-SA 4.0

Where? Stinging nettles are a typical indicator plant for nitrogen-rich soils, whose growth and spread is promoted in particular by nitrogen input. Four species of stinging nettle occur in Central Europe, which grow very undemandingly and therefore colonize a wide range of habitats.The most common species is Urtica dioica. Appearance? Nettles grow as an annual or perennial herbaceous plant with (depending on the species) growth heights between 10 and 300 cm. The often square stems are partly branched, partly unbranched and grow mostly upright or ascending. All green parts of the plant are covered with stinging and bristly hairs. The leaves are usually arranged cross-opposite, have an elliptical, ovoid or circular appearance and are usually toothed at the leaf edge.. Special features? Typical of stinging nettles are the stinging hairs, which break off on contact and release stinging liquid into and onto the skin, causing (depending on the species) more or less painful wheals.   "Urtica dioica Stinging Nettle - Schmitz Park" by brebooks is licensed under CC BY-SA 2.0   "Utrica diocia" by Anna is licenced under CC BY 2.0

Where? Mead wort grows in much of Europe on moist to wet soils, with nutrient-rich and weakly to moderately acidic soils. It is a light to semi-shade plant and is usually found in ditches, watercourse margins and wet meadows. Aussehen? Mead wort is a perennial, herbaceous plant that reaches growth heights of 50 to 150 centimeters. The stems are reddish in color and branch only above, below the inflorescences. The leaves are dark green and have a white down on the underside. The inflorescences bloom from June to August and consist of many small cream to yellowish white flowers that develop into slightly twisted nutlets after the flowering phase. The flowers give off an intense honey to almond-like odor. Special features? In almost all of Europe the mead wort is native, in North America it is an undesirable neophyte. In both Europe and America, it is considered an undesirable pasture herb that is avoided by grazing animals, so it is controlled in many places. It is used in many places to flavor foods and beverages because of its smell and taste. It has also been used in part as a fragrant plant and in herbal medicine   "Filipendula ulmaria – meadowsweed – Echtes Mädesüß" by Nichlas Turland is licensed under CC BY-NC-ND 2.0   "Filipendula ulmaria" by Michael Wunderli is licensed under CC BY 2.0

Where? Grows mostly in sunny locations with slow flowing and stagnant waters with water depths of min. 80 cm. Appearance? The most common water lilies are perennial herbaceous aquatic plants, anchored by a long rhizome from the soil surface. Alternating aquatic and floating leaves are formed, in a heart-shaped to arrow-shaped or oval to roundish form with a characteristically incised leaf blade. Flowers rise from July to September above the water surface and can be of different colors depending on the species.. Special Features? Some pond and water lilies can be toxic, especially the white water lily can cause respiratory paralysis.   Nymphaea daubenyana - "Starr 010914-0052 Nymphaea sp." by Forest & Kim Starr is licensed under CC BY 3.0   "Nymphaea caerula" by Palmbeaches974 is licensed under CC BY-SA 3.0

Where? Grows in nutrient-rich, stagnant to slow-flowing waters at depths of 1.5 to 3 meters. Appearance? Perennial, herbaceous, always submerged plant with alternate, up to 4.5 cm wide and up to 30 cm long, pointed and slightly transparent pale green to yellow leaves. Between June and September, spikey inflorescences form, which emerge above the water surface.   "Potamogeton lucens" by Andreas Rockstein is licensed under CC BY-SA 2.0   "Shining Pondweed - Potamogeton lucens" by Jeremy Halls is licensed under CC BY-SA 3.0  

Where? Water mint is a plant from the mint genus and is found in large parts of Europe and Africa. It grows mainly on somewhat acidic, muddy soils, on moderately nitrogen-rich sites, on banks and ditches, in wet and boggy meadows and swamp forests. It can also grow underwater in depths up to 2 meters. Appearance? Water mint grows as a perennial herbaceous plant that reaches heights of 10 to 150 cm. The four-edged stem grows opposite, ovate leaves with toothed margins that grow between 2 to 8 cm long and 1 to 4 cm wide. The flowers are close above the upper leaf axils and form spherical inflorescences. The flowers have a light purple, pink or white coloration and consist of five leaves each up to 4mm long. Special Features? Very typical for the water mint is the smell of mint, which occurs especially when rubbing the leaves.    "Water Mint (Mentha aquatica)" by Edward Baker is licensed under CC BY-NC-SA 2.0   "Mentha aquatica" by Jörg Hempel is licensed under CC BY-SA 2.0

Where? River water-crowfoot grows in fast-flowing rivers and streams in moderately warm to warm areas. Appearance? River water-crowfoot is a wintergreen, herbaceous plant that forms stems up to 6 meters long. On it grow at least 8 cm long, thread-like and multi-branched submerged leaves. Between June and August form white flowers with yellow stamens that have a diameter of up to 2 cm. Special features? Underwater, egg-shaped stipules are formed, above water, small fruits are formed, which contain between 34 and 63 nutlets.   "River-water crowfoot - Braid Burn" by Magnus Hagdorn is licensed under CC BY-SA 2.0   "Flutender Hahnenfuß" by Grzegorz Grzejszczak is licensed under CC BY-SA 4.0

Where? Bogbean (Menyanthes trifoliata) grows in shallow water and spring swamps of rivers, in fen forests, intermountain fens, and on edges of upland bogs. Appearance? Bogbean is a perennial, herbaceous plant that grows up to 30 cm tall and forms rhizomes up to finger-thick, from which 12 to 20 cm long leaf stalks grow, each with three elliptical, smooth leaves. From April to June, inflorescences form on the leaf axils on up to 30 cm long, leafless shafts, with, per flower, five pink to pure white sepals. Special Features? Bogbean has been used as a remedy and is said to help with digestive problems. However, the originally assumed fever-reducing effect cannot be proven. They can cause headaches, vomiting and diarrhea.   "MenyanthesTrifoliata6" by Christian Fischer is licensed under CC BY-SA 3.0   "Bogbean - Menyanthes trifoliata" by Björn S... is licensed under CC BY-SA 2.0

Where? Butterbur requires seepage-wet or partially flooded, nutrient-rich soils and therefore often grows along stream and river banks. Appearance? Butterbur is a perennial herbaceous plant that reaches growth heights between 10 and 40 cm, and up to 120 cm at fruiting time. It grows from a brownish rhizome about 4 cm thick. The leaf stalk growing from it is hollow inside and shows distinct ridges and can reach diameters of up to 60 cm, growing only after the flowering period. The flowers grow on a separate, reddish stem, appear between March and May and grow as a densely standing reddish-white to red-purple inflorescence. Special features? The plant was and is used as a medicinal plant after controlled processing, but is toxic to humans in its natural state.   "Petasites hybridus - butterbur - Gewöhnliche Pestwurz" by Nichlas Turland is licensed under CC BY-NC-ND 2.0   "Petasites hybridus" by Andreas Rockstein is licensed under CC BY-SA 2.0

Where? Ground elder (Aegopodium podagraria) grows primarily in nitrogen-rich, shady, moist, loose soils. Due to the strongly proliferating rhizome, the low demands and thus rapid spread, it is generally considered a troublesome weed. Appearance? The Ground elder is a partially wintergreen, perennial herbaceous plant that reaches heights of 30 to 100 cm. The alternate leaves are ovate-oblong, have a serrated margin and consist of 2 to 3 leaf segments. The flat and 12- to 25-rayed inflorescence consists of many small white flowers that bloom from June to July. Special Features? Ground elder was used as a medical plant in the Middle Ages, but its effect has not been proven. It is also considered a tasty wild vegetable.   "Blütendolden Girsch" by 4028mdk09 is licensed under CC BY-SA 3.0   "Aegopodium podagraria (48°11' N 16°03' E)" by HermannFalkner/sokol is licensed under CC BY-NC-SA 2.0

Where? Hemp-agrimony (Eupatorium cannabinum) usually thrives in moist meadows, wet meadow fallows, on the banks of ditches and streams, or along forest edges and in woodlots. Common waterwort is a nutrient and moisture indicator. Appearance? Hemp-agrimony is a deciduous, perennial, herbaceous plant that reaches growth heights of 50 to 175 centimeters. The erect, short-haired, richly leafy stem, branched only in the upper part, often has a reddish tinge. The stem leaves are arranged opposite and usually palmate with 3-5 pinnae with toothed leaf margins. The total inflorescence contains numerous, small, dense, partial inflorescences. The corollas contain four to six tubular flowers of five pink, rarely white petals. The flowering period is from July to September Special Features? Hemp-agrimony is widespread throughout Europe, western Asia, and northern Africa. In North America and Australia it is a neophyte. Insects love the Hemp-agrimony.   "Eupatorium cannabinum, Hemp-agrimony, Koninginnekruid" by ekenitr is licensed under CC BY-NC 2.0   "Eupatorium cannabinum 1" by Hladac is licensed under CC BY-SA 4.0

Where? Bur-reed (Sparganium) are a plant genus of the bulrush family and occur in about 21 different species. They grow on damp to wet, temporarily or always flooded sites on water banks, swamps and bogs. Due to their (under suitable conditions) very dense stands, they form so-called reed beds.They often occur together with cattails, sedges and rush species. Appearance? Bur-reed species are green overwintering perennial herbaceous plants, some of which grow completely underwater or with floating leaves and inflorescences at or above the water surface. The alternate deciduous leaves are oblong, grass-like in shape, and consist of a spongy floating tissue. The inflorescence consists of male and female spherical partial inflorescences that grow as white to dark green, spiny-looking flower heads.     "Sparganium erectum. Forest Farm Pond. 1990" by Dr Mary Gillham Archive Project is licensed under CC BY 2.0   "Sparganium fluctuans (floating bur-reed), Abbey Pond, Ripton, VT" by Doug McGrady is licensed under CC BY 2.0

Where? Epilobium hirsutum grows scattered in shrubberies along streams, ditches, springs and in the fringe of willow scrub. It loves loamy, somewhat calcareous soils. Appearance? Is a perennial herbaceous plant with growth heights of 50 to 180 cm. The erect, richly branched stem is densely hairy with protruding hairs. The lower leaves are almost cross-opposite, the rest alternate. The leaf blades are narrow-lanceolate with a length of 6 to 12 cm and a width of 1 to 4 centimeters. The leaf margins have strong denticles. The flowering period is between July and September. Its purple petals are radially symmetrical and have a length and diameter up to 2 cm. Special Features? Occasionally,the Great willowherb is cultivated as an ornamental plant, so in Australia and America it is considered a widespread neophyte.   "4837-epilobium-hirsutum-20110718" by Malte is licensed under CC BY-SA 3.0   "23875415" by birding16 is licensed under CC BY-NC 4.0   Great willowherb in the withered state Rasbak, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

Where? Golden saxifrage (Chrysosplenium) grow in Central Europe in wet places next to streams or on rocks in mountain gorges. However, many species also grow in drier places in rock crevices or on gravel slopes. Appearance? The Golden saxifrage form a genus of plants of the Saxifragaceae family with about 57 to 65 species. They are a small, perennial, herbaceous plant, with growth heights of 10-20 cm. The stem leaves can be opposite or alternate, are always undivided and grow without stipules, Characteristic of spleenworts are the inflorescences, which are usually surrounded by yellow to green, flat bracts. The calyx consists of usually four yellow, green or even reddish brown sepals with 4, 8 and rarely 10 stamens. The central ovary consists of 2 carpels, the bracts, sepals, stamens and carpels are mostly on one level..     "Chrysosplenium oppositifolium (Opposite-leaved Golden Saxifrage)" by pluralzed is licensed under CC BY-ND 2.0   "Chrysosplenium japonicum 7" by Qwert1234 is licensed under CC BY-SA 4.0

Where? Prefer sunny to light-shaded places that are wet to moist. It grows especially well directly in the water at depths of maximum 40 centimeters of water on heavy clay soils. Appearance? Grows as a perennial herbaceous plant, which can reach growth heights of 1 to 2 m. The gray-green sword-shaped leaves grow up to 90 cm long and 1-3 cm wide. The inflorescence consists of a yellow trifoliate single flower, from which cylindrical fruits are formed, 4 to 8 cm long, containing many seeds. The flowering period lasts from the end of May to June. Special Features? This plant has been used as a form of water treatment since it can take up macronutrients (such as nitrogen and phosphorus) through its roots, and is featured in many AS Level Biology practicals as its ability to grow in low pH levels makes it a useful indicator. All plant parts of the plant are poisonous. Partly it is used as an ornamental plant for garden ponds and water banks.   "Sumpf-Schwertlilie (Iris pseudacorus) (01)" by Rüdiger Stehn is licensed under CC BY-SA 2.0   "Yellow Iris - Iris pseudacorus" by Hornbeam Arts is licensed under CC BY-NC 2.0

Where? Reed canarygrass often grows in large groups along or in flowing, oxygen-rich waters on nutrient-rich clay and mud soils, occasionally on dry sites. It is a light-loving species, but also tolerates partial shade. Appearance? Reaches growth heights of 0.5 to 2 meters and has elongated, grass-like, hairless leaves that usually grow over 15 mm wide. The youngest leaves are usually rolled. The flowers at the end of the stem are 10-20 cm long panicles consisting of several small branches, each with one flower. The flowering period is from June to July. Special Features? Can root up to 3.5 meters deep and is popularly grown as a mowing grass, as it is very productive and suitable as a forage grass.   "4382804" by Matthew Salkiewicz is licensed under CC BY-NC 4.0   Leaf base is hairless (in contrast to that of the reed). Rasbak, CC BY-SA 3.0 , via Wikimedia Commons   "3978121" by Paul Marcum is licensed under CC BY-NC 4.0

Where? Cattails are an typical aquatic and marsh plant that can develop very dense stands in wetlands. They usually settle on the banks of water bodies, in marshes and swamps on moist to wet sites. Appearance? Are deciduous perennial plants that have alternate leaves on stems that are always hairless. The leaves grow stiffly erect and can reach a length of up to 4 meters. They are grass-like in shape and consist of a spongy compressible webbing. The leaf blades are curved outward to form a semicircular cross-section. The total inflorescence consists of a thicker (all-female) and an above all-male subinflorescence. The inflorescences are cylindrical to spherical in shape with very dense flowers. The flowering period is from May to August. Special Features? Typha species are distributed worldwide and consist of up to 40 different species.     "Narrow leaf cattail (Typha angustifolia)" by John Brandauer is licensed under CC BY-NC-ND 2.0   "Typhaceae - Typha minima-1" by Hectonichus is licensed under CC BY-SA 3.0

Where? Grows gregariously as a reed bed on banks or in ditches with standing or slowly flowing water and strongly changing water levels. It prefers nutrient- and base-rich, mostly calcareous, humic muddy soils and is light- and heat-loving. Appearance? Reed mannagrass is a perennial herbaceous plant 80 to 150 (sometimes 200) cm tall, with widely creeping, stout rhizomes. The culms are round with up to 1 cm in diameter. The leaves are glabrous and rough, growing up to 60 cm long and up to 2 cm wide. The flower panicles grow between 20 and 40 cm long and stand in clusters of spikes up to 1 cm long. The spikes are narrowly elongated with five to eleven brownish white flowers. The flowering period is from June to August. Special Features? Is a nutritious forage plant and is readily eaten by cattle and horses. On riverbanks it is suitable for the containment of erosion.   "19874975" by Grzegorz Grzejszczak is licensed under CC BY-SA 4.0   "Glyceria maxima" is licensed under public domain

  Liverworts Where? Mosses of the liverwort group (Marchantiophyta) can be found on many stream banks or in moist areas near springs. They grow in individual groups or in extensive lawns on stones or on nutrient-poor soils in the shade. Of these, some are more sensitive to nutrients, such as the liverwort Chiloscyphus polyanthos (see photo below), which is found in Luxembourg, and some are less so. The most widespread is the fountain liverwort (Marchantia polymorpha). Appearance? Liverworts grow rather flat and often overlay each other like lobes. Some form a kind of cup on their surface. Many liverworts form spore capsules after some time, which are roughly comparable to fertilized seeds of higher plants. The liverwort Pellia endiviifolia is found in fresh to wet, shady to semi-shady locations in woods or on the banks of streams.  "File:Apopellia endiviifolia 67745395.jpg" by Christian Grenier is marked with CC0 1.0. Liverworts tend to grow flat and planar, often overlapping like lobes. "File:Apopellia endiviifolia 84402440.jpg" by Calum McLennan is licensed under CC BY 4.0. The liverwort Pellia endiviifolia, like many other mosses, forms spore capsules after some time, which are roughly comparable to fertilized seeds of higher plants. The reproductive mechanisms of mosses are complicated. "File:Pellia endiviifolia (fb, 144835-474709) 5112.JPG" by HermannSchachner is marked with CC0 1.0.     The liverwort Chiloscyphus polyanthus found in Luxembourg.It grows, for example, in shady forest streams, forest springs, ditches, in bogs and swamps. "File:Chiloscyphus polyanthos (a, 143553-482324) 3413.JPG" by HermannSchachner is marked with CC0 1.0. Umbrella liverwort (Marchantia polymorpha), forms cups on its surface. sys-one (Franz Mattuschka), CC BY-SA 3.0 , via Wikimedia Commons   Water-Mosses Where? The group of spring mosses belong to the mosses living under water. The moss Philonotis fontana, colonizes light-rich, lime- and nutrient-poor, mostly cold spring areas. It occurs in bogs…

Where? Shore zones of lakes or ponds. The roots can tolerate waterlogging. Appearance? The blooming period of the showy yellow and bushy flowers extends from spring to summer, depending on location and distribution area. The inflorescence stem in the middle or upper stem area, leaf axillary is 1.5 to 3 centimeters long, smooth or sparsely glandular or shaggy hairy.   Lysimachia thyrsiflora WFNY-163.jpg, Public Domain   "Lysimachia thyrsiflora sl50" by Stefan.lefnaer is licensed under CC BY-SA 4.0.   "Tufted Loosestrife (Lysimachia thyrsiflora) - Time, Norway 2021-08-07" by Ryan Hodnett is licensed under CC BY-SA 4.0.

Where? The water-starwort (Callitriche) form a group of plants living in water. They are creeping annual to perennial herbaceous plants living on the bottom or partially or completely under the water surface. They belong to the natural vegetation of a river. Appearance? The shoot axis grows filiform and is covered with opposite leaves. The shape and arrangement of the leaves varies greatly depending on the location. Plants located below the water surface often have lanceolate or linear leaves and long internodes. An upper portion of the leaves and flowers often float in carpets on the water surface. Special features? There are several Callitriche species that are sensitive to overly nutrient-rich water (eutrophic). These include Callitriche cophocarpa, recognizable by its lance-shaped, longer leaves. Likewise, there are Callitriche species such as Callitriche obtusangula that are tolerant of water pollution and are considered indicators of eutrophic waters. Unlike Callitriche cophocarpa, Callitriche obtusangula has rounder leaves. However, beware that other Callitriche species also have rounded leaves. So if there are water-starwort swimming on your brook or river, look for other indicators and see if your water-starwort matches your observations.     Identifying characteristics: lanceolate, longer leaves. Callitriche cophocarpa is found in streams or rivers with little polluted or eutrophic water. "File:Callitriche cophocarpa.jpg" by Jan Prančl is licensed under CC BY 3.0.   Identifying characteristic: round leaves of Callitriche obtusangula Callitriche obtusangula Le Gall, 1852 by Tenesse85 is marked with Public Domain Mark 1.0.

  Invasive? Trachemys is a genus of turtles belonging to the family Emydidae. Trachemys spec. probably entered Europe as pets through the pet trade. They are native to the southern United States and northern Mexico, but have also been introduced to us due to pet releases and are displacing the native European pond slider (Emys orbicularis) from their habitat in many areas. Where? The turtles live in slow-moving rivers as well as floodplains, marshes, temporary wetlands, and ponds. Appearance? There are three subspecies, two of which are found in Luxembourg to date. The yellow-bellied slider (Trachemys scripta scripta) has an oval greenish to brownish dorsal carapace about 12-21cm, a yellow ventral shield and narrow yellow chin stripes. The red-eared slider (Trachemys scripta elegans) can be clearly recognized by its red temporal stripes. Distribution map in Luxembourg: https://neobiota.lu/trachemys-scripta-scripta-2/ Please report the species, if you have seen it, via neobiota.lu     The yellow-bellied slider (Trachemys scripta scripta) has an oval greenish to brownish dorsal carapace about 12-21cm, a yellow ventral shield and narrow yellow chin stripes. "Male slider (Trachemys scripta scripta), Botanic Garden, Munich, Germany" by Diego Delso, CC BY-SA 3.0   The red-eared slider (Trachemys scripta elegans) can be clearly recognized by its red temporal stripes. "Red-eared Slider Turtle (trachemys scripta elegans)" by woodleywonderworks is licensed under CC BY 2.0.    

Invasive? Orconectes limosus, the Spiny-cheek crayfish and its congeners Pacifastacus leniusculus, the Signal crayfish and Procambarus fallax, the Marbled crayfish all originate from North America and nowadays inhabit almost all flowing waters. They are carriers of the deadly fungus "crayfish plague", to which they themselves are resistant. Since the crayfish grow faster, reproduce more strongly and are much more aggressive, they are biologically superior to the native European crayfish Astacus astacus and displace it even without transmission of the crayfish plague. Since the signal crayfish is very similar to the noble crayfish, it has also been released by humans into various lakes. Where? The crayfish are quite shy, which is why you can often only spot dead animals or moulting carapaces. Being nocturnal animals, they like to stay hidden in their hiding places or among aquatic plants during the day. They are omnivores. Both crayfish prefer cool rivers, but can also cope with warmer still waters. Appearance?   The signal crayfish - Pacifastacus leniusculus Are brownish to olive, carapace smooth. On the upper side of the claws at the joint there is a turquoise-white signal spot (name!), which is sometimes only weakly pronounced or even missing. The undersides of the claws are red. Distribution in Luxembourg: https://neobiota.lu/pacifastacus-leniusculus/ Please report the species if you have seen it via the website link.    "Pacifastacus leniusculus, Ecrevisse de Californie Lac du Bourget_1( pêche INRA automne 2017)" and "Pacifastacus leniusculus, Ecrevisse de Californie Lac du Bourget_2 (pêche INRA automne 2017)" by photonat3873017107 is licensed under CC BY-NC-SA 2.0. The crayfish - Orconectes limosus Are brownish to olive in color, characteristic are the spines on the cheeks in front of the nuchal furrow and the orange tips of the claws. Distribution in Luxembourg: https://neobiota.lu/orconectes-limosus/Please report the species if you have seen it via the website link.    "Spinycheek…

Invasive?/Where? It is mostly found in larger rivers, but migrates towards the sea once in its life, as the offspring need salt water to develop. The young crabs then migrate in turn to freshwater. During these mass migrations upstream, it contributes to temporary local extinctions of native invertebrates, but it feeds primarily on aquatic plants. Its intense burrowing activity alters habitats along the way. Crabs can also be encountered on land as they avoid barriers in their migration. The species originated in Asia and was introduced to Europe in the early 20th century. They are carriers of the deadly fungus "crab plague", to which they themselves are resistant. Appearance? Unmistakable by the hair fur on the claws, but in females and juveniles it is not so pronounced. The dorsal carapace can be olive green to brown with dark spots, but there are also bluish and purple color variations. The carapace is finely serrated at the edge. Distribution in Luxembourg: https://neobiota.lu/eriocheir-sinensis/ Please report the species, if you have seen it, via neobiota.lu "Eriocheir sinensis" by ondrej-radosta is licensed under CC BY-NC 4.0   "Eriocheir sinensis" by sanher is licensed under CC BY-NC 4.0

  Invasive? The American bullfrog was deliberately imported from its native area the eastern part of North America, from the 19th century to Europe, bred and repeatedly released. It was an asset for gastronomy, ornamental trade and served as fishing bait. They compete with native frog and amphibian species for spawning sites, food, and habitat. The frogs' abundance is probably boosted by warm winters, when fewer hibernating American bullfrogs die. Where? The American bullfrog lives in still waters rich in plants, such as lakes, ponds and swamps. It prefers warmer waters. The call of the males is quite loud and reminds of ox calls. Aussehen? It is one of the largest frog species in the world (15-20 cm in body size), making it larger than all native frog species. The tadpole can also grow up to 14 cm. Recognizing feature of adult animals is the strikingly large eardrum below the eyes. The body is olive green to gray-brown in color and often dark spotted. The sound bladder in males is located on the throat and not on the side as in native water frogs. Distribution in Luxembourg:https://neobiota.lu/lithobates-catesbeianus/    "Ouaouaron (Lithobates catesbeianus)" by Bouligab is licensed under CC BY-SA 2.0 "Lithobates catesbeianus DT [Z Yanzatza] 0803 (14)" by Archivo Murciélago Blanco is licensed under CC BY-SA 2.0

  Invasive? The quagga mussel is apparently displacing the zebra mussel (D. polymorpha), which was introduced more than 100 years ago and is found almost everywhere. It is spreading further and further south via large rivers and canals. Where? With the help of its adhesive foot, it can attach itself to stones, concrete walls or ship hulls. It owes its rapid spread to its dispersal mechanism via the free larvae, which only attach themselves to a substrate after about over a week. Appearance? The colors are very different, the has a beige to dark brown shell and is often clear longitudinally striped. The quagga mussel is recognizable by rounded shell sides. The shell sides are also asymmetrical, if you look at the shell from the side they are wavy and not flat on top of each other as in the native triangular mussel.

Invasive? The stone moroko originates from river systems in East Asia, it was unintentionally first imported to Romania via eggs in 1960. It is insensitive to temperature fluctuations and tolerates low O2 levels in the water, therefore it is considered very adaptable which is an advantage over native species. It has a negative impact on other fish and amphibian species due to competition for food and spawn predation. The stone moroko selectively eats larger zooplankton species (Crustacea), which leads to increased phytoplankton density and thus favors the eutrophication of water bodies. Where? It occurs both on the shore zones of still waters and in flowing waters, it prefers summer warmed zones and plant-rich waters. Appearance? The stone moroko is a small fish species and rarely grows larger than 10 cm. The scales are metallic shimmering, and along the body side, especially in young fish a black-blue stripe. Distribution in Luxembourg: https://neobiota.lu/pseudorasbora-parva/

  Invasive? The nutria is a rodent from South America, which was introduced to Europe mainly for fur farming. It feeds on stems of aquatic plants and thus destroys reed zones and fish nurseries. It also plunders the nests of marsh birds.  Where? The nutria lives on the banks of wide rivers or lakes and also in other wetlands. They build a den at the water's edge and defend their territory. Often nutria live together in pairs or groups. It can often be observed swimming or gnawing on the shore. Aussehen? Nutria have a yellow-brown to black colored fur, their nail teeth are orange. The long rat-like tail is scaled and somewhat hairy. They have small ears and long thick whiskers, between the 1st and 4th toe of the hind feet are webbed. Distribution in Luxembourg: https://neobiota.lu/myocastor-coypus/ Please report the species, if you have seen it, via neobiota.lu "Stéphanie Baumard - Ragondin (Myocastor coypus) - Camargue" by Images pour des mots is marked with CC0 1.0 "Beverrat (Myocastor coypus)" by Hennie Cuper is licensed under CC BY-NC 2.0

  Invasive? The Black bullhead originates from the Great Lakes region in North America. It can be bought in pet stores for aquariums and garden ponds, over these ways it probably also found its way into wild waters. In 1934 the first Black bullheads were found in Northern Europe, in Southern Europe they have been established for a long time. Black bullhead are omnivorous and feed on insect larvae, leeches and crustaceans as well as the spawn of other animals and usually prevail in competition with other fish species. In smaller waters, Black bullhead can become the dominant fish species, displacing other fish species and amphibians. They also tolerate high CO2 and low O2 levels in water bodies as well as pollution from sewage. The species populations are currently still insignificantly small, but due to the high "invasive potential" they should remain under observation. Where? Black bullhead live in larger lakes and ponds, but also in slow-flowing waters with soft or muddy bottoms. Appearance? The Black bullhead is easily confused with the Brown bullhead (Ameiurus nebulosus). It has 8 barbels (whiskers), the back is dark gray to black, the belly is light. Adult animals grow between 25 and 35 cm long. The base of the whiskers is black in A. melas, light in A. nebulosus. Distribution in Luxembourg: https://neobiota.lu/ameiurus-melas-rafinesque-1820/   "File:Hal - Ameiurus melas - 1.jpg" by Emőke Dénes is licensed under CC BY-SA 4.0.   "Ameiurus melas" by fishesoftexas is licensed under CC BY-SA 4.0.

  Invasive? The jellyfish probably originated in the Yangtze River in China. How the freshwater jellyfish came to Europe is unclear - but probably as a stowaway of an imported pond plant. Since it reproduces asexually by division, it can spread rapidly. The freshwater jellyfish probably has no major ecological impact on native animal and plant species. Where? It is found in warm, clear, slow-moving and stagnant waters. Most of the time it lives in the polyp stage attached to plants. It needs water temperatures of at least 25°C to develop into a medusa. In warm summers the jellyfish often appear in masses, they are harmless to humans. Appearance? Their rather small whitish, transparent umbrella has a diameter of about 6 mm to 20 mm. It is the only species of the native cnidarians that besides the polyp stage has a medusa stage, so it looks like a classic jellyfish.

Invasive? The Armerican skunk abbage or yellow skunk cabbage was spread to Europe through the garden trade and parks and originated in North America. Lysichiton plants can grow up to 1.2 m tall under favorable conditions on semi-shaded, nutrient-rich and acidic sites near bodies of water. They develop leaves up to 50 cm wide. This competitive effect can push back typical animal and plant species, such as sphagnum mosses, marsh violets, and orchids. Lysichiton americanus can thus pose a threat to the vegetation of wetland sites, including, for example, spring sites. Where? Amerivan skunk cabbage grows best in nutrient-rich soils, wetlands and moist forests with shade. But also occurs on the banks of standing or flowing water. Appearance? SAmerican skunk cabbage is a large swamp perennial with strikingly large, undivided, stalked, tobacco-like leaves that can grow up to 1.5 m long. The plant grows close to the ground and does not grow particularly tall. The attractive inflorescence, a green 12-20 cm long spadix surrounded by a yellow bracts (spatha), appears in early spring before the leaves. Berry fruits with 1-4 seeds each are formed on it. The inflorescence and fruit set is thus similar to that of the native arum. The leaves of the native arum at arrow-shaped, sometimes black spotted leaves that are not longer than 30 cm. Distribution in Luxembourg:  https://neobiota.lu/first-documented-observation-of-lysichiton-americanus-in-luxembourg/   The large leaves of skunk cabbage „Korina 2010-08-10 Lysichiton americanus 1“ by Katrin Schneider is licensed under CC BY-SA 4.0.   The yellow flower of skunk cabbage "File:Yellow Skunk Cabbage - geograph.org.uk - 605523.jpg" by Jonathan Billinger is licensed under CC BY-SA 2.0.  

  Invasive? The Himalayan balsam is originally from the Himalayas and was brought to Europe as an ornamental plant. It has a very professional way of spreading ( watch the Video) and that is what makes it so dangerous to native plant life, as it threatens to out compete other plants. The flowers of the Himalaya balsam have the highest nectar production in Europe and attract numerous pollinators.Since the end of the first decade of the 21st century, the Himalayan balsam has been increasingly spreading across the landscape, leaving riverbanks and colonizing other habitats such as roadsides and forests. An example of this is the Our valley between Stolzembourg and Dasbourg-Pont, where the balsam has managed to "jump" over the main road, climb the steep slopes and "invade" the oak forests. Meanwhile, Impatiens glandulifera also occurs in many forests and forest edges. Over the past 20 years, the spread of I. glandulifera into forest habitats has accelerated and may have been aided by the strong dispersal tendency of riparian populations, major anthropogenic or natural disturbance of forest ecosystems, increased use of forestry equipment capable of transporting seeds, and the high environmental tolerance of the species. Impacts of I. glandulifera in forest habitats may include negative effects on native plant and mycorrhizal fungal diversity. I. glandulifera may also have a negative impact on the growth of planted forest plants. Where? Found frequently in masses especially on the banks of many waterbodies, but also on roadsides, slopes, cities and forests. It prefers moist and relatively nutrient-rich soil. Appearance? The Himalayan balsam is an annual plant, it can be found from spring to summer. It grows quickly and can grow up to 3 meters high. The leaves grow opposite and are strongly serrated. The white, purple or pink flowers grow in flower groups …

  Invasive? Japanese knotweed was introduced to Europe from East Asia in 1823 as an ornamental and garden plant. It and also its genetical intersections (hybrids) can be easily released into the wild, are competitive, and form dense stands that crowd out native vegetation. Although it can grow almost anywhere, all perennial knotweed prefers the banks of streams. The above-ground parts die back in winter, leaving bare banks that are subject to erosion. No seeds are produced, but Fallopia japonica reproduces clonally. Stems and roots easily break into small pieces, and a new plant can regenerate from the fragments. The main ways of spreading are transport of garden waste and soil contaminated with root fragments. If the plant is strongly consolidated on riverbanks, it is also spread by floods and can easily establish itself downstream. Where? Like other knotweed, Japanese perennial knotweed colonizes a wide range of habitats, with a preference for moist and nitrogenous soils. It prefers sunny spots or partial shade. This pioneer plant spreads in both ruderal and semi-natural habitats, including riparian areas and open woodlands. Appearance? Confusion? The identification of knotweed species is not always easy, especially of the existing very similar looking hybrid. In 2017, the museum was able to show that in Luxembourg the cross F. × bohemica is more common than Fallopia japonica. It is a natural fertile hybrid of Japanese knotweed (Fallopia japonica) and Sakhalin knotweed (Fallopia sachalinensis). Fallopia x bohemica has characteristics of both Japanese knotweed and Sakhalin knotweed. There are leaves with a rectangular as well as with a heart-shaped base. Often a distinction is not clear, so that finds in doubt can also be called "Fallopia spec."

Invasive? Giant hogweed originated in the Caucasus and was introduced to Europe as an ornamental. And garden plant introduced to Europe. Its enormous growth height (over 3 m) and leaf area enables it to crowd out most native herbaceous plant species. It can form dense stands that absorb up to 80% of incoming light, displacing most light-demanding species. If it grows on riverbanks, the seeds can be dispersed by water for miles. In addition to ecological problems, tall invasive hogweed species also pose a serious health threat to humans. The plant secretes a clear watery sap that contains several photosensitizing furanocoumarins. Upon contact with human skin and in combination with ultraviolet radiation, these compounds cause severe burns to the skin (Branquart et al. 2010). After flowering, the plant parts die, leaving unattached riparian soil and the risk of erosion. Where? Giant hogweed grows on moist and nutrient-rich soils in ruderal habitats, along roadsides, riverbanks and forest edges, in abandoned or neglected meadows and in tall herbaceous communities. It is rarely found in older ecosystems such as forests, but can occur in open floodplain forests. Appearance? The stem is hollow and furrowed, it bears purple spots, especially in the lower part. It can grow up to 10 cm thick at the base. The leaves grow up to 1 (rarely up to 3) m long, they are 3-5-lobed with pinnatifid segments. The umbrella-like or plate-like inflorescence can reach 80 cm in diameter and consists of white to pink flowers. The ripe fruits are flat and have upward curved bristles, especially on the edge. Distribution in Luxembourg/ Action Plan: https://neobiota.lu/heracleum-mantegazzianum/   "File:Jättebjörnloka (Heracleum mantegazzianum) i Väsmestorp, Sörby sn 5186.jpg" by Gunnar Creutz is licensed under CC BY-SA 4.0.   "File:Riesen-Bärenklau 01 (Heracleum mantegazzianum).JPG" by Hajotthu is licensed under CC BY 3.0.  

  Distribution in Luxembourg / Action Plan: https://neobiota.lu/helianthus-tuberosus/ Invasive? Helianthus tuberosus is native to central and eastern North America. Probably cultivation for eating the root tubers brought him to Europe. Under Western European climatic conditions, the plant does not produce viable seeds and reproduces vegetatively. Tubers and root pieces (rhizomes) are transported by rodents and running water, especially during winter floods. The plant can form dense and persistent monocultures along rivers, where it usually displaces native species by shading and competing for other resources.. Where? Helianthus tuberosus, prefers light-rich, sandy, moist and nutrient-rich soils. It thrives best in locations that are repeatedly flooded by high water (riverbanks), but can also be found in ruderal areas and in agriculture. Appearance? The plant grows up to 3 m high, the stem is round and rough hairy. The stalked leaves are broad-lanceolate, with serrated margins, rough on top and finely soft-hairy underneath. They grow up to 25 cm long and 10 cm wide and are opposite in the lower part of the stem, alternate above. The yellow flowers are erect and 4 to 8 cm in diameter. Tongue and tube flowers are yellow. The plant blooms from September to October. Distribution in Luxembourg / Action Plan: https://neobiota.lu/helianthus-tuberosus/   Jerusalem artichoke habitus "File:Helianthus tuberosus Paludi 02.jpg" by Syrio is licensed under CC BY-SA 4.0.   Edible root tubers of Jerusalem artichoke "Helianthus tuberosus 'White Round', Tsaghkadzor, in culture" by Vahe Martirosyan is licensed under CC BY 2.0.   Jerusalem artichoke flowers "Helianthus tuberosus Paludi 06" by Syrio is licensed under CC BY-SA 4.0.

Invasive? This perennial submerged plant forms dense populations that often colonize entire water bodies, restricting water movement, blocking light, creating anoxic conditions, and accelerating sediment deposition. Because of its rapid nutrient uptake and very high growth rate, the species displaces native aquatic plants.The species' original range in North America extends from Quebec through Montana to Washington, and south to North Carolina and California. Spread is by vegetative propagation: shoot parts are transported widely by flowing water, marine traffic, water sports equipment (including fishing), and waterfowl. A new waterweed population grows from the shoot fragments. Where? Elodea nuttallii is an underwater plant that grows in various types of freshwater habitats, from stagnant to slow-flowing waters. It is very tolerant of water pollution and prefers warm, eutrophic and calcareous waters. It is often found in species-poor aquatic plant communities. It is more nutrient tolerant than its sister species Elodea canadiensis and can even survive in wastewater with concentrations up to 27.2 mg NH4+-N/l. Thus, it benefits more from water pollution than E. canadensis. Elodea nuttallii can form dominant stands in nutrient-rich, stagnant or slow-flowing waters. In hypertrophic waters, dominance stands of narrowleaf waterweed can occur especially after nutrient levels are reduced. Appearance? In addition to the Canadian pondweed (E. canadensis) and the Western waterweed, the Argentine waterweed (E. callitrichoides; with flat, longer leaves) is also found in our area, but all species are quite difficult to distinguish. Waterweed species are perennial submerged aquatic plants. Their densely leafy shoots creep or grow erect. They are about 1 mm thick and up to 300 cm long. The light green narrow leaves of this species are 3-cornered to linear, long-pointed, up to 10 mm long and 0.4 - 1.5 (-2.4) mm wide. In the lower stem area they are alternately arranged, in the upper area…