Welcome to our A to Z Glossary of Pond Terms and Aquatic Plants - your essential guide to understanding everything related to ponds, aquatic plants, pond maintenance, and wildlife habitats. Whether you're designing a wildlife pond, maintaining water quality, or selecting the best marginal plants, this glossary provides clear, concise definitions of key terms, including oxygenators, floating plants, pond pests, and natural filtration. Ideal for garden pond owners, landscapers, and aquatic plant enthusiasts, this resource helps you make informed decisions to keep your pond healthy, balanced, and thriving.
Jump to a section:
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
Aeration – The process of increasing oxygen levels in pond water using pumps, fountains, or water movement.
Algae Blooms – Rapid overgrowth of algae caused by excess nutrients, often from fertiliser runoff. This can deplete oxygen levels and harm pond life.
Amphibian – Cold-blooded animals such as frogs, toads, and newts that depend on water for part of their life cycle. They lay eggs (spawn) in ponds, and their larvae develop in water before transitioning to land.
Aphids – Small sap-sucking insects that cluster on marginal plants, causing leaf curling and spreading plant diseases.
Aquatic Basket – A specially designed basket for planting pond plants. These baskets allow water and nutrients to flow through while holding the soil and preventing excessive spreading.
Aquatic Fertiliser – A nutrient supplement used to promote healthy plant growth in ponds. It must be slow-release to prevent excess nutrients from degrading in water and triggering algae blooms.
Aquatic Plants – Plants that grow in or around water, categorised as floating, submerged, deep water, or emergent.
Aquatic Soil – A clay-based soil designed to anchor pond plants while minimising nutrient leaching into the water.
B
Backswimmer (Water Boatman) – An aquatic insect that swims upside down and preys on small fish, tadpoles, and insects.
Bacterial Leaf Spot – A bacterial disease that affects marginal plants, causing small, dark spots on leaves. If untreated, it spreads and leads to tissue decay.
Biofilter – Aquatic plants that absorb excess nutrients from the water, helping to control algae growth and improve water clarity.
Blanketweed – A filamentous type of algae that forms dense, stringy mats on the water’s surface. Requires control to maintain pond health.
Bog Garden – A wet, low-lying area designed for plants that thrive in saturated soil conditions.
Bubble Pump – A water circulation system used in natural swimming ponds to improve oxygen levels and prevent stagnation by releasing fine bubbles from the pond floor.
Bunched Oxygenators – Oxygenating plants sold in bunches rather than potted, to be placed directly in the water.
Bulrush (Scirpus & Typha) – A tall, grass-like wetland plant that grows in the shallow margins of ponds and lakes. Often confused with reeds.
C
Caddisfly Larvae – Aquatic insect larvae that build protective cases from pond debris and are an important food source for fish and amphibians.
Cattail (Typha) – Also known as bulrushes, these reed-like plants have tall stems and distinctive brown flower spikes.
China Mark Moth Caterpillars – A pest that affects floating plants like waterlilies. The larvae chew holes in the leaves and roll them to create protective shelters.
Clay-Lined Pond – A pond constructed using natural clay to retain water instead of a synthetic pond liner.
Clump-Forming – A plant growth habit where plants grow in tight clusters rather than spreading aggressively. Example: Irises
Coir Matting – Biodegradable coconut fibre mats used for erosion control and to support plant growth.
Constructed Wetland – A man-made wetland designed to filter water, manage stormwater, or support wildlife habitats.
Container Pond – A small, self-contained pond created in a container, such as a large pot, barrel, or trough.
Creeping (Growth Habit) – A type of plant growth where stems spread along the surface of the water or soil, rooting at nodes. Example: Marsh St John's Wort (Hypericum elodes)
D
Damselfly – Small, slender insects related to dragonflies. They lay eggs in aquatic plants, and their larvae develop underwater, feeding on tiny aquatic insects.
Deadhead – The removal of spent flowers from aquatic and marginal plants to encourage further blooming and maintain plant health.
Deep Water Plants – Aquatic plants that grow in deeper pond zones, typically over 30cm of water.
Dissolved Oxygen (DO) – The amount of oxygen available in pond water, essential for fish, plants, and aquatic life.
Dragonfly – Large, fast-flying insects that hunt mosquitoes, flies, and other small insects around ponds and wetlands. Their larvae live underwater for several years.
Drown (Plant Drowning) – Some aquatic plants, such as waterlilies, can drown if placed too deep before their leaves reach the surface.
Duckweed – Tiny, free-floating plants that form a green carpet on water surfaces, often indicating nutrient-rich water.
E
Emergent Plants – Plants rooted underwater with leaves, stems, and flowers rising above the water surface, e.g., sedges, bulrushes, and reeds.
Emerging Wildlife Habitat – Areas where aquatic plants provide shelter and breeding grounds for amphibians, insects, and birds.
Erosion Control – The use of aquatic plants to stabilise pond banks and prevent soil erosion. Plants like Carex (sedges) and Phragmites (reeds) help prevent shoreline degradation.
Epiphytic Algae – Algae that grow on the surfaces of plants, rocks, and hard surfaces in a pond. While some are beneficial, excessive growth can block sunlight from reaching aquatic plants.
Eutrophication – The process where excess nutrients (e.g., from fertilisers or runoff) cause rapid algae growth, reducing oxygen levels and harming aquatic life.
F
Field Pond – A pond found in agricultural landscapes, often created to support biodiversity and provide water for livestock.
Filamentous Algae – A stringy, hair-like algae that forms mats on the water surface or clings to plants and rocks. A common type is blanketweed.
Filter Bed – A planted area within or beside a pond designed to filter and clean water using natural filtration plants.
Flood-Resistant Garden – A garden designed to cope with flooding, using marginal and aquatic plants that can adapt to fluctuating water levels.
Floating Plants – Aquatic plants that float freely on the water surface, helping to shade the pond and control algae growth. Examples include water lettuce, frogbit, and duckweed.
Frog – Amphibians often found in ponds, helping to control insect populations. Common UK species include the Common Frog (Rana temporaria).
Fungal Infections (Saprolegnia) – A common waterborne fungal infection affecting fish, amphibians, and plants. It appears as cotton-like growths on affected areas.
Fungal Leaf Spot – A fungal disease that causes brown or yellow spots on plant leaves, reducing photosynthesis and plant health.
G
Genus – A taxonomic category grouping species with shared characteristics, such as Nymphaea (Waterlilies) or Lobelia (Lobelias).
Goldfish – Popular ornamental fish that may nibble on aquatic plants if natural food sources are insufficient.
Grass (Aquatic & Wetland Grasses) – Various grass species that thrive in moist or aquatic environments, often used for habitat restoration and erosion control.
Great Diving Beetle (Dytiscidae) – A large predatory beetle that feeds on tadpoles, small fish, and other aquatic insects.
Green Water (Algal Bloom Effect) – A pond water condition caused by suspended microscopic algae, which turns the water murky green. Can be controlled using UV clarifiers, floating plants, and biofilters.
H
Hardy Aquatic Plants – Cold-tolerant pond plants that can survive winter without needing to be brought indoors, e.g., waterlilies and yellow flag iris.
Hessian – A woven fabric traditionally used in planting but not needed with modern aquatic baskets as they retain soil while allowing water movement.
Hibernaculum – A shelter for amphibians, often made of logs, stones, and leaf litter, providing a frost-free area for winter hibernation.
Hornwort (Ceratophyllum demersum) – A submerged oxygenating plant that improves water clarity and oxygen levels. Unlike other oxygenators, it does not need planting and can float freely.
Hydrophyte – A plant adapted to growing in or near water, such as waterlilies, oxygenators, and marginal plants.
Hydroponic Planting in Ponds – Some floating aquatic plants absorb nutrients from the water without soil, helping reduce algae growth by removing excess nitrogen and phosphorus.
I
Invasive Species – Non-native plants or animals that spread aggressively and disrupt local ecosystems, e.g., Azolla (Water Fern) and Crassula helmsii (New Zealand Pygmyweed).
Isopods (Aquatic Woodlice) – Small crustaceans that live in ponds and wetlands, feeding on decaying plant material and helping break down organic matter.
J
Japanese Knotweed – An aggressive invasive plant that spreads rapidly along watercourses, damaging pond margins and outcompeting native vegetation.
Juvenile Amphibians – The young stage of frogs, toads, and newts that have recently transitioned from their larval (tadpole) stage to land-dwelling adults.
Juncus (Rushes) – A wetland plant genus that includes species like Soft Rush (Juncus effusus), which grows in marginal zones and helps prevent soil erosion.
K
Keratinous Beak (Tadpoles) – The small, toughened mouthparts of tadpoles, used to scrape algae off pond surfaces and aquatic plants.
Koi Carp – Large ornamental fish often kept in ponds. While beautiful, they are not ideal for wildlife ponds as they uproot plants and stir up sediment, reducing water clarity.
L
Leeches – Found naturally in ponds, leeches feed on detritus and small invertebrates. Some species prey on fish and amphibians.
Linear Planting (Pond Shelves) – The method of planting marginal plants along the edge of a pond, often measured per metre of shelf length to calculate plant quantity.
Log Pile – A collection of logs and branches stacked together to create shelter for amphibians and insects near ponds.
M
Marginal Plants – Aquatic plants that grow in shallow water or at the pond’s edge. Examples include; Yellow Flag Iris (Iris pseudacorus) and Marsh Marigold (Caltha palustris).
Marginal Shelf – A shallow ledge in a pond where marginal plants are placed. Ensure the depth matches the plant’s requirements before digging a shelf.
Marsh Plants – Plants that thrive in saturated soil conditions but can tolerate periods of drought. Examples include Water Mint (Mentha aquatica) and Purple Loosestrife (Lythrum salicaria).
Microhabitat – A small, specialised area within a pond that supports specific plants and wildlife. Examples include shallow water zones, boggy edges, and submerged plant beds.
Molluscs (Pond Snails & Mussels) – Soft-bodied aquatic animals such as Ramshorn Snails and Trapdoor Snails, which help filter pond water by feeding on algae and organic debris.
Mosquito Larvae – The early-stage larvae of mosquitoes, commonly found in stagnant water. Fish, frogs, and water beetles naturally keep their numbers in check.
N
Native Pond Plants – Plants naturally found in UK ponds and wetlands, supporting local wildlife.
Natural Swimming Pond – A chemical-free alternative to a traditional swimming pool, relying on aquatic plants, beneficial bacteria, and biofilters to keep the water safe and fresh.
Newt – Amphibians that breed in ponds and help control insect populations. UK species include Smooth Newt, Great Crested Newt (a protected species), and Palmate Newt.
Nutrient Overload – A high level of nutrients (mainly nitrogen and phosphorus) in pond water, often caused by fertiliser runoff or decaying plant matter.
Nymphaea (Waterlilies) – Floating-leaved deep-water plants that provide shade, reduce algae growth, and create shelter for aquatic life.
O
Organic Debris – Leaves, algae, and decomposed plant matter that build up in ponds over time, affecting water quality and increasing the risk of low oxygen levels.
Overcrowding – A condition where aquatic plants are planted too closely together, leading to reduced growth, lack of light, and competition for nutrients.
Overwintering (Pond Plants) – Some aquatic plants, like waterlilies, enter a dormant phase during winter and regrow in spring. Tender plants need to be moved indoors in colder months.
Oxygenators – Submerged plants that produce oxygen and improve water clarity by reducing excess nutrients. Examples include Hornwort and Water Crowfoot.
P
Pesticide Runoff – A pollution issue where rainwater carries pesticides into ponds, harming aquatic life and causing imbalances in the ecosystem.
Pollinator-Friendly Plants – Aquatic or marginal plants that attract bees, butterflies, and other pollinators, supporting biodiversity. Examples include Pickerel Weed (Pontederia cordata) and Water Forget-Me-Not (Myosotis scorpioides).
Pond Beetle – A predatory insect that feeds on algae and other pond life, contributing to a balanced ecosystem.
Pond Flea – Tiny crustaceans that feed on algae, helping to regulate pond health.
Pond Liner – A synthetic or natural barrier used to prevent water seepage in ponds. Options include rubber, PVC, and clay liners.
Pond Skater – Insects that glide on the surface of the water, feeding on small insects trapped in the pond.
Pond Snail – Small snails that graze on algae and detritus. Some species can overpopulate and damage soft aquatic plant growth.
Potted Oxygenators – Oxygenating plants grown in aquatic pots rather than being sold in bunches. Useful for controlling spread in formal pond setups.
Powdery Mildew – A fungal disease appearing as a white, powdery coating on leaves, reducing plant health. It thrives in damp conditions and is more common in bog and marginal plants.
Predatory Water Bugs – Insects such as water scorpions and backswimmers that prey on tadpoles, small fish, and aquatic insects.
Protective Netting (Pond) – A fine mesh cover placed over ponds to prevent leaves from falling in, deter predators, and protect fish from birds.
R
Ramshorn Snails – A type of aquatic snail that feeds on decaying plant matter. While beneficial in small numbers, large populations may eat soft aquatic plant tissues.
Ranavirus – A serious viral disease affecting frogs, toads, and newts, causing lethargy, ulcers, and population declines. It spreads through infected pond water, contaminated footwear, and infected spawn.
Reed (Phragmites & Glyceria) – Tall, grass-like marginal and wetland plants that help stabilise pond banks, provide shelter for wildlife, and filter pollutants from water.
Regeneration Zone (Natural Swimming Ponds) – The biological filtration area of a natural swimming pond, where aquatic plants, oxygenators, and beneficial bacteria naturally filter and clean the water.
Rhizome – A horizontal underground stem that produces new shoots and roots. Many aquatic plants, such as Iris and Waterlilies, spread via rhizomes.
Riparian Zone – The interface between land and a body of water, often populated with aquatic plants that stabilise soil and provide habitat for wildlife.
Root Rot – A fungal disease caused by waterlogged soil, leading to decayed roots and plant death. It affects marginal plants if the soil remains too saturated for long periods.
Runoff (Polluted Water Runoff) – The flow of rainwater or irrigation water into ponds, which may carry pollutants, pesticides, and fertilisers that impact pond health.
S
Sedge – A grass-like wetland plant with triangular stems, commonly found in marginal pond areas and bog gardens.
Spacing (Aquatic Plants) – Proper spacing of pond plants prevents overcrowding and ensures better growth, nutrient availability, and water circulation.
Spawn – The eggs of amphibians such as frogs and toads. Frog spawn appears in clumps, while toad spawn forms long, jelly-like strings.
Spider Mites – Tiny arachnids that damage plant leaves, particularly in dry conditions. They can be problematic for bog and marginal plants.
Spread (Waterlilies) – Measured as Miniature, Small, Medium, or Large, referring to how far the leaves will extend across the water surface.
Supports Pollinators – Plants that attract bees, butterflies, and other beneficial insects, contributing to pondside biodiversity.
Surface Cover Plants – Plants that spread across the pond surface, providing shade, reducing algae growth, and offering protection for aquatic life. Examples include Frogbit (Hydrocharis morsus-ranae) and Waterlilies (Nymphaea).
T
Tadpole Stage (Amphibians) – The aquatic larval stage of frogs, toads, and newts, where they breathe through gills before developing legs and lungs.
Tender (Not Frost Hardy) – Plants that cannot survive freezing temperatures and must be overwintered indoors or in a greenhouse. Examples include Water Lettuce, Smooth Frogbit, and Elephant Ear.
Toad – Amphibians that live in and around ponds. The Common Toad (Bufo bufo) is widespread in the UK. Unlike frogs, toads have drier, bumpier skin and prefer walking over jumping.
Turbidity (Cloudy Pond Water) – A measure of how clear or murky pond water is, often caused by suspended algae, fish activity, or fine sediment particles.
Typha – A genus of aquatic plants commonly known as bulrushes in the UK. Found in wetlands and pond margins, they provide habitat for birds, insects, and aquatic wildlife.
U
Underwater Plants – Also known as submerged plants, these species grow entirely below the water surface and play a key role in oxygenating the pond and improving water quality.
Ultraviolet (UV) Clarifier – A device used in pond filtration systems to help control green water algae by exposing pond water to ultraviolet light, which kills free-floating algae spores.
V
Vernal Pools – Seasonal ponds that fill with water in winter and dry out in summer, providing important breeding grounds for amphibians like newts and frogs.
Vigorous Growth (Aquatic Plants) – A term describing fast-spreading plants that can quickly cover large areas of a pond or wetland.
Vine Weevils – A pest that affects marginal and bog plants. Larvae destroy roots, while adult weevils chew holes in leaves, leading to plant decline.
W
Water Beetle (Dytiscidae & Gyrinidae Families) – Aquatic beetles that prey on pond insects, tadpoles, and algae, playing an important role in maintaining ecological balance.
Water Boatman (Corixidae Family) – A group of aquatic insects that feed on algae and detritus. Unlike Backswimmers, they do not bite and are beneficial for pond health.
Water Garden – A designed garden featuring aquatic plants, often incorporating water features such as ponds, waterfalls, or fountains.
Water Hyacinth (Eichhornia crassipes) – A once-popular floating plant, now banned in the UK since 2014 due to its invasive nature. Alternatives: Try Water Lettuce for similar floating cover or Water Soldier, a UK-native option.
Water Lily Beetle (Galerucella nymphaeae) – A pest that chews holes in waterlily leaves, reducing plant vigour. Controlled by manually removing beetles and larvae and encouraging natural predators like birds and frogs.
Water Snail – Small gastropods that graze on algae and organic debris. While beneficial, species like Great Pond Snails can become overpopulated and damage soft aquatic plant growth.
Water Quality (Pond Health Indicator) – A measure of clarity, oxygen levels, pH balance, and nutrient content that determines pond ecosystem stability.
Waterfowl (Ducks, Swans, Geese) – Birds that live in and around water. While they add beauty to a pond, they can also be destructive, uprooting floating and emergent plants and stirring up sediment. Floating plant protectors or shallow planting zones can help minimise damage.
Waterlilies (Nymphaea) – Deep-water aquatic plants with floating leaves and vibrant flowers. Essential for providing shade, shelter for aquatic life, and oxygenation in ponds.
Wildlife Pond – A pond created specifically to support native plants and animals, often left fish-free to prevent disturbance to amphibians, insects, and aquatic invertebrates.
Winter Dormancy (Pond Plants) – A survival strategy where hardy pond plants die back in autumn and regrow in spring, such as Waterlilies and Irises.
Y
Yearly Pond Maintenance – Seasonal pond tasks such as removing excess plant growth, checking water quality, and preparing for winter dormancy.
Z
Zooplankton – Tiny aquatic organisms that feed on algae and serve as a crucial food source for fish, amphibian larvae, and aquatic insects.
Zonation (Pond Plant Zones) – The natural division of plants within a pond, based on water depth and plant tolerance.