Plants
Plants of the Somerset wetlands
The Somerset wetlands support a wide range of habitats including improved grasslands, fens, remnant bogs and reedbeds with open water. The area is one of the largest areas of coastal grazing marsh in the whole of the British Isles, with over 50,000 ha of this poorly drained marsh grassland. Since the last ice age which ended some 12,000 years ago, the vegetation of the Somerset Levels and Moors has undergone enormous changes. Initially an extensive saltmarsh slowly developed into a freshwater marsh. This was then colonised by wet woodland and then developed into a large raised bog.
Wildflower meadows
Since the second world war much of this wetland has been agriculturally improved by the application of inorganic fertilisers and herbicides together with improved drainage. Where fields have remained unfertilised and managed traditionally by cutting and grazing, wildflowers create a riot of colour during the spring. With Common Bird’s-foot-trefoil Lotus corniculatus, Common Knapweed Centaurea nigra, Meadow Vetchling Lathyrus pratensis and Oxeye Daisy Leucanthemum vulgare flowering in profusion. The umbellifers Corky-fruited Water-dropwort Oenanthe pimpinelloides and Pepper-saxifrage Silaum silaus are occasionally found in the unimproved meadows. The best wildflower meadows are home to Green-winged Orchid Anacamptis morio, sadly this orchid is now a very rare plant on the Levels. Other Orchid species are commonly encountered in the meadows include Southern Marsh-orchid Dactylorhiza praetermissa and Heath Spotted-orchid Dactylorhiza maculata.
Raised bog habitat
Peat has been extracted from the Avalon Marshes since at least the Roman period. With extensive areas being exploited for peat extraction since the 1950s. The extraction of peat, mainly for use in horticulture and in gardens, has destroyed most of the raised bog. Within the Avalon Marshes there are now just four areas remaining that represent the vegetation of the once widespread raised bog habitat. Typical plants of this bog habitat included Cross-leaved Heath Erica tetralix and the beautiful Bog Pimpernel Anagallis tenella. There are a few low growing shrubs such as Bog myrtle Myrica gale and Alder Buckthorn Frangula alnus. Wetter areas support Common Cotton Grass Eriophorum angustifolium, Round-leaved Sundew Drosera rotundifolia, Marsh Pennywort Hydrocotyle vulgaris and Marsh Willowherb Epilobium palustre.
Rare tall herb fen
One of the rarest habitats in the Somerset Wetlands is that of tall herb fen. The very best example is known as the Catcott Parish Plot, owned by the local Parish Council. In the absence of grazing a tall herb fen community develops. Much of the site is dominated by Meadow sweet Filipendula ulmaria, Yellow Iris Iris pseudacorus and Marsh-marigold Caltha palustris. Also Greater Bird’s-foot-terfoil Lotus pedunculatus, Common Meadow-rue Thalictrum flavum, Water Horsetail Equisetum fluviatile and Hemp-agrimony Eupatorium cannabinum.
Wet woodland
Some areas of Avalon Marshes are best classified as wet woodland. Some areas remain wet during much of the year, others are only wet in the winter time. Here Alder Alnus glutinosa, Silver Birch Betula pendula and Downy Birch Betula pubescens frequently form the main component of these woodlands. Many have an understory of ferns such as Royal Fern Osmunda regalis. This is the largest of Britain’s ferns and a long-lived plant that can grow to a height of 1.6m.
Extensive ditch network
An important habitat on the levels is the very extensive ditch network. Typical plants here include Hairlike Pondweed Potamogeton trichoides and Curled Pondweed Potamogeton crispus. The underwater leaves of Bladderwort Utricularia sp, have branches that are covered in tiny bladders, with the capability of catching small invertebrates. During late spring across the surface of the ditch there is a bright green layer of small floating plants, collectively known as Duckweeds. These tiny plants can sometimes produce a minute flower. There are at least four species that are frequently encountered including Common duckweed Lemna minor and Fat duckweed Lemna gibba. Emerging from the surface of the ditches is one of the Levels most attractive plants, the Flowering-rush Butomus umbellatus. The drainage system of the levels has a different suite of aquatic plants. Very common is Yellow Water-lily Nuphar lutea that can cover the surface of many of these slow flowing rivers.
Open water habitats
Over the past 20 years conservation organisations have been restoring the worked-out peat voids into a series of open water habitats with extensive reedbeds. Bulrush Typha latifolia and in a few places Lesser Bulrush Typha angustifolia can also start to dominate. Tall growing reed like grasses Common Reed Phragmites australis, Reed Canary-grass Phalaris arundinacea and Reed Sweet-grass Glyceria maxima are also common.
Recording Somerset's wetland plants
RoAM has an important role to play in recording these wetland plants and monitoring their presence as the different habitats evolve and work is undertaken to restore them.