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Offwell Wetland Survey

Area C - Swamp Zone

emergent.jpg (102732 bytes)

This area is permanently covered in standing water. It lies on the edge of the open water zone and gives way to marsh behind it, where the standing water levels vary and the sediment is not permanently covered by water.

 

water_mint.jpg (96584 bytes) On the southern edge of the wetland where the water depth is 1-10 cm deep, plants such as Water Mint (at left), Yellow Iris, Greater Reedmace, Branched Bur-reed, Willow and Common Duckweed are found in abundance. As water depth increases, the emergent vegetation develops into pure stands of Branched Bur-reed, with Canadian Pondweed and Various-Leaved Water-Starwort submerged beneath the water surface and Duckweed floating on the top. Branched Bur-reed dies out where the water depth exceeds 50 cm.
 

In the western swamp region of the wetland the composition of the vegetation is somewhat different. In the shallower regions, Water Mint, Yellow Iris, Greater Reedmace, Branched Bur-reed and Willow are found as in the southern swamp area, although here with the addition of Water-plantain, Greater Spearwort and Bogbean. The deeper water areas here consist of pure stands of Bogbean.

In both regions, the substrate is composed of a deep fibrous tangled mass of rhizomes, roots and old leaf bases. The underlying sediment is black and anaeorobic.

Swamp plant adaptations


Plant Species List for Area C

Salicaceae

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Salix caprea agg. Goat Willow
Betulaceae

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Alnus glutinosa (L.) Gaertn. Alder
Ranunculaceae

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Ranunculus lingua L. Greater Spearwort
Onagraceae

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Epilobium palustre L. Marsh Willowherb
Callitrichaceae

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Callitriche platycarpa Kutz. Various-leaved Water-Starwort
Callitriche stagnalis Scop. Common Water-Starwort
Menyanthaceae

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Menyanthes trifoliata L. Bogbean
Labiateae

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Mentha aquatica L. Water Mint
Rubiaceae

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Galium palustre agg. Marsh Bedstraw
Alismataceae

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Alisma plantago-aquatica L. Water-plantain
Hydrocharitaceae

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Elodea canadensis Michx. Canadian Pondweed
Potamogetonaceae

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Potamogeton natans L. Broad-leaved Pondweed
Graminae

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Glyceria fluitans (L.) R. Br. Floating Sweet Grass
Juncaceae

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Juncus effusus L. Soft Rush
Iridaceae

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Iris pseudacorus L. Yellow Iris
Lemnaceae

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Lemna minor L. Common Duckweed
Sparganiaceae

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Sparganium erectum L. Branched Bur-reed
Typhaceae

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Typha latifolia L. Greater Reedmace

 

These species lists are not exhaustive. They represent initial collections and identifications carried out in early autumn. Many species of flowering plants may already have flowered and died back at this time and would therefore have been missed. These lists will be updated periodically.

 

         Back to Areas page         Complete Survey Species List           Back to Wetland diagram

       

Wetland Survey Contents


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