What is this Pond Plant? It's Fairy Moss or Azolla caroliniana

Hello I was wondering if somebody would be able to help me with a query. I am a wildlife photographer based in Kent, England and in March of last year was taking some photographs at Hampstead Heath, London. I have a photograph of what I think is some kind of algae or pond plant and need to find out exactly what it is so that I can enter a photo featuring this ’algae’ into a competition. I would be glad of any help.

Please find attached a detailed photograph of the 'algae'. Thanks very much, Jodie Randall

The picture is shown below ... click to enlarge. With help from my friend Peter J May in the UK I managed to get an answer for Jodie.

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Its Azolla caroliniana or Fairy Moss. It increases rapidly by division and tints in sunlight and towards autumn into a ruby colour although some varieties stay a red/brown. In the UK it used to get knocked back by the frosts and over wintering bodies sink to the bottom of the pond.
But in the milder areas now it is becoming a bit of a pest. In fact most authorities say to avoid it at all costs.
Where it doesn't die back it forms a thick light excluding blanket over the water that emergent plants can struggle to get through.
It is in fact a fern and is commonly called Mosquito fern or water fern in some places. There is a blue-green algae called Anabaena which it is symbiotic with that lives in the cavities of the of the lower surfaces of the leaves. This fixes nitrogen for the plants. This makes it excellent compost material.

Where to buy pond plants on-line at good prices

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Image	Link to Plant at Store
	Dwarf Cattail: Typha minima is perfect for small water garden ponds and containers such a half barrel tubs. This dwarf cattail grows to less than 2' tall, making it extremely well suited to small garden ponds or container gardens! Distinctive rounded brown seed heads sit atop blue-green foliage. Even survives very low temperatures! Click to buy
	King Tut Papyrus: Cyperus papyrus 'King Tut'. An ideal water garden marginal or bog garden plant. King Tut Papyrus is an outstanding aquatic for use in your garden pond! King Tut Papyrus is also known as the umbrella plant because of its eye-catching green bracts bend over. King Tut Papyrus will grow well in both full sun or partial shade. This aquatic plant can be planted directly into water or rich, moist soil (bog). The plant is hardy down to 25 degrees F. It can be taken indoors for the winter. Click to Buy
	Sweet Flag Water Grass: Acorus calamus. Sweet Flag Water Grass is a popular water grass that has long narrow leaves. The leaves have a strong sweet smell when crushed in the hand. The iris-like foliage is dramatic in ponds or for edging around pots. Sweet Flag Water Grass sports yellow-green flowers in summer. Shade tolerant and hardy in zones 4-11. Click to Buy
	Iris:, Louisiana 'Black Gamecock': The Louisiana 'Black Gamecock' Iris is one of the most adaptable Irises that can grow under almost any condition. This plant is a native of wetlands and can be grown in water gardens. Fortunately for most of us, the Louisiana 'Black Gamecock' Iris is easily adaptable to normal growing conditions. Huge, 4" velvety-black blooms surround yellow markings. Grows to 24". Zones 4-10. Click to Buy.
	Juncus 'Big Twister': Unique twisting and turning upright spirals! One of a kind grass loves to be planted in wet soil conditions. Makes a perfect addition to water gardens. Can be planted in shallow water (up to 6" deep). Prefers hot, sunny conditions. Grows 18-24". Click to Buy.
	Houttuynia, The chameleon plant : Houttuynia cordata "Chameleon"... Here's your opportunity to grow something your friends and neighbors don't already have. Only recently have there been quantities sufficient enough to offer it to customers. The Houttuynia has exotic, chameleon-shaped leaves -- a bright blend of greens, bronze, and yellows. It has white flowers in early summer. Grows 6 to 9 inches. The Houttuynia is a brightly colored plant that is very popular in the Orient. It is easy to grow. Thrives almost anywhere. Order this Oriental beauty with its rainbow coloring and easy grow ability today!. Click to Buy
	Globeflower: Trollius chinensis 'Golden Queen' ... A colorful waterside addition! Extremely large, golden-orange buttercup summertime flowers make Golden Queen an outstanding perennial. Plants are excellent for waterside areas or bog gardens. Can be planted in other areas as long as it is kept constantly moist. Grows to 30" tall Prefers sun to partial shade. Zones 3-7. Click to Buy.
	Marsh Marigold: Caltha palustris. Excellent pond plant too! Marsh Marigold produces beautiful masses of flowers that resemble double marigolds from mid-spring through early-summer. An excellent planting at the edge of a pond. Can also be planted in water at a depth of no more than 4". Requires full sun. Zones 3-10. We send number one plants. Click to Buy.
	Water Lily Collection: These water lilies were specially chosen for their superior qualities of hardiness, vivid color and long blooming season. They will provide your pond with color all summer long for many years. All four varieties are winter hardy to -30 degrees and can remain in ponds during the winter where the water does not freeze to the level of the plant. They are easily stored for winter in colder climates. All bloom from June to September. Water depth for all varieties is 18-24". Planting instructions included. This collection includes 1 each of Yellow, White, Pink and Red water lilies. Click to Buy.
	Water Lily, Red: Nymphaea ' Attraction' ... Specially chosen for their superior qualities of hardiness, vivid color and long blooming season. House of Wesley's Water Lilies will provide your pond with color all summer long for many years. All varieties are winter hardy to -30 degrees and can remain in ponds during the winter where the water does not freeze to the level of the plant. They are easily stored for winter in colder climates. All bloom from June to September. Water depth is 18-24". Click to Buy.
	Water Lily, Yellow: Nymphaea ' Sulphurea'... Specially chosen for their superior qualities of hardiness, vivid color and long blooming season. House of Wesley's Water Lilies will provide your pond with color all summer long for many years. All varieties are winter hardy to -30 degrees and can remain in ponds during the winter where the water does not freeze to the level of the plant. They are easily stored for winter in colder climates. All bloom from June to September. Water depth is 18-24". Summer splash of creamy yellow flowers that stay open much later in the afternoon than other varieties. Cup shaped flowers measure 2-6" across. Very free flowering. "> Click to Buy.
">	Water Lily, White: Nymphaea 'mariacea Albida'... Top performer in the water! Specially chosen for their superior qualities of hardiness, vivid color and long blooming season. House of Wesley's Water Lilies will provide your pond with color all summer long for many years. All varieties are winter hardy to -30 degrees and can remain in ponds during the winter where the water does not freeze to the level of the plant. They are easily stored for winter in colder climates. All bloom from June to September. Water depth is 18-24". Click to Buy.
	Water Lily, Pink: Nymphaea 'Fabio'... Specially chosen for their superior qualities of hardiness, vivid color and long blooming season. House of Wesley's Water Lilies will provide your pond with color all summer long for many years. All varieties are winter hardy to -30 degrees and can remain in ponds during the winter where the water does not freeze to the level of the plant. They are easily stored for winter in colder climates. All bloom from June to September. Water depth is 18-24". Once this pink beauty starts to bloom, it doesn't stop. Selected because it usually blooms with several flowers at one time. Slightly fragrant. Click to Buy.