Flora of Ashdown Forest - Botanical Society of the British Isles

192Potamogeton natans. Broad-leaved pondweed.,--;---===-----;-, Frequent on the Forest (Hall 1980).Common in suitable habitats during our survey, occurring generally in deeper waterin the bigger ponds and lakes and often forming large patches by itself. It tends to occurin open water but will persist in ponds for some time 85 they become grown over andshaded. It has a broad range of water tolerance from nutrient-poor to nutrient-richconditions. One cattle trough on The Farm (393.329), 1995, TR, had a good patchgrowing well in clean tap water. It is also planted in some ponds, as in new ponds inPipping ford Park.4 5Widespread in Sussex except the west, and throughout the northern hemisphere.Potamogeton po/ygonifolius. Bog pondweed.Ashdown Forest, abundant, E. Jenner (Arnold 1887). Ashdown Forest IWhitwell 1902).Pools on Ashdown Forest near Gills Lap, etc. (Done 1914). Six tetrad records for theForest (Hall 1980).It occurs in the smaller flushes and shallow ponds on acidic soils, and has evenbeen seen in a dried-up, shaded stream in South bank Wood (433.315), 1995, TR.Although associated particularly with more acidic habitats, it is less common on theForest than the previous species, presumably because it has more specialised4 5requirements.It is occasional in the Weald. Common throughout Britain, and mainly in westernand central Europe. It also occurs in north-western Africa and eastern North America.Potamogeton berchtoldii. Small pondweed.Recorded in the pond near Newgale Farm, 1988, PW (confirmed by E. G. Philp) which isthe record in Briggs (1990).Not present in 1994, but refound again in abundance around the margins in 1995after the pond had been opened up. Some plants had unusually wide leaves (2.2 - 2.43 mm) which were at or slightly beyond the widest value (2.3 mm) given in Preston(1995). Waterfowl were observed to eat it.Occasional in Sussex. Scattered throughout Britain and much of the northern4 5hemisphere ill a broad rallge of aquatic habitats and water quality conditions.ARACEAE*Lysichiton americanus. American skunk-cabbage.Planted and spreading in Maskett's Wood (428.285L 1995, Flora meeting; planted atChelwood Vachery in bog garden (429.296), 1994, MR, PR & TR; spreading downstream at Kidbrooke 1420.345), 1995, TR.Introduced and increasing in England (Rich & Woodruff 1996). Native in western3 North America where it grows in similar boggy, wet woodlands.4 5* Calla palustris. Bog arum.] -++_----'iL-----'-+_Planted in pond in Pippingford Park (444.301), 1993, SBRS; one plant in iron flush inshaded alder wood at Newbridge (455.323), 1993, PD & TR, presumably spread downthe stream from Pippingford Park. This is the first naturalized record for East Sussex.Occasionally naturalized in Britain and Ireland. Native in Europe, North Asia andNorth America.4 5