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Flora of Cornwall (1999)

The descriptive text, below the map, is from the Flora of Cornwall (1999), which was a Tetrad Atlas (the maps had 2km square dots or Tetrads). The map on this web page depicts the plant's distribution at the 1km square scale and shows the records made pre-2000 which were used in the 1999 Flora and those made since.

Polygonum maritimum - Sea Knotgrass

Nationally Rare, a protected and Red Data Book species, Sea Knotgrass is a plant of sand and fine shingle, growing at, or just above High Water of Spring Tides. Erratic in appearance, in 1962 it was being considered 'extinct on the mainland of Great Britain' ( Watsonia 5 , 212). Refound at Lantic Bay in 1972 (SW15K, P. Ward) and in 1978 (R.W. David), it was plentiful in 1982. It then became very intermittent in occurrence, only one plant being seen here in 1990 (P.A. Gainey). The last record for Lantic Bay was made in 1991. However, in 1990, it appeared at Church Cove, Gunwalloe (SW62Q, P. Bowman) as a result of clearing work on the beach by the National Trust (Murphy, 1991). Its last confirmed record here was in 1935 (Thurston, 1935). Despite tourist pressures, it has continued to flourish at Gunwalloe and in 1998 the population numbered more than 500 (R.J. Murphy). In the same year (1998), Sea Knotgrass was found on Par Beach (SX05W, K.G. Preston-Mafham), this time after an absence of 60 years. This beach is also under tourist pressure, but a careful search revealed a total of 35 plants (I.J. Bennallick).

Click here to see Aphotoflora images by David Fenwick


French, C.N., Murphy, R.J. & Atkinson, M. 1999. Flora of Cornwall. Wheal Seton Press, Camborne.