Flora of Ashdown Forest - Botanical Society of the British Isles

139CONVOLVULACEAEConvolvulus arvensis. Field bindweed, Lily.Common on the Forest (Hall 1980).Frequent on waste ground, in gardens and lawns, occasional on mown andslightly disturbed road verges. The flowers last only one day each, opening in themorning and closing by the afternoon. Grime et al. (1988) note that its distribution3 -++---'""'"---......'../--and seed-set in Britain appear to be limited by climate. It is drought-tolerant andmore common on south-facing slopes, and the roots may be damaged by freezing.A pernicious weed in Sussex except on the Ashdown Sands. Widespread inBritain and temperate regions of the world.4 5Calystegia sepium. Hedge bindweed, Grandmother's or Grandfather's Night-cap, Woodbine.Common on the Forest (Hall 1980).Widespread around the Forest though avoiding the acidic areas, and especiallyfrequent along hedges off the Forest. Not all records may be C. sepium sensu strictoas vegetative plants cannot be determined with certainty, but it does seem to bemore common than C, silvatica.This species and C. silvatica are markedly selfMincompatible, and as smallpopulations are usually single clones, little or no seed is set (Waiters & Martin 1958).Seed is however set in larger or obviously heterogeneous populations, and sometimesthey hybridise with C. si/vatica (we have not looked for hybrids).Very common in Sussex and widespread in lowland Britain and temperate regions.[Ca/ystegia pu/chra. Hairy bindweed.Tetrad 33V (Hall 1980); not refound and probably not in our Flora area.)* Calystegia silvatica. Large bindweed.Frequent on the Forest (Hall 1980).Occasional around the edges of the Forest, usually in the villages and nearhouses. It often forms large patches scrambling over hedges and verges, It iscertainly less frequent than C, sepium, as it is elsewhere in Sussex, Widespread in3 lowland Britain. Native in southern Europe, the Caucasus and North Africa.4 5CUSCUTACEAECuscuta epithymum. Dodder, Devil's guts, Hell weed. (Account by SR).On Ashdown Forest (Caleman 1836). Webb (1885) found it in great quantitiesparasitic on fifteen different species "among others oak, hawthorn, agrimony, gorse,needle whin, heath, ling, wax-heath, Blechnum fern, both on barren and fertile fronds,and bracken. It was very plentiful on gorse, heath and ling, but not so much on theothers. In general the flowers were pinkish, hanging in little round bunches on deeppurple stems, but I also observed some with pure white flowers attached to palegreen stems, they did not grow in such full clusters as the purple ones did. Thegreen plant was not in a more sheltered situation than the purple", On the Forest4 5(Firmin 1890). Specimens collected by Miss P. Stockdale in 1911 were parasitic onCalluna, Erica tetralix, Vlex minor and Origanum (BEX). On furze near Crow borough (Done 1914). AshdownForest, 1934, D. P. Young (BRC). Frequent south of Forest Row, 1948, R. A. Boniface. Ashdown Forest,abundant after fire (Ross 1955). Near Nutley, 1957, R. A. Boniface (BRC). Frequent on the Forest (Hall 1980).We have also recorded it scattered throughout the Forest, usually on rides and never abundant thoughprobably most noticeable in 1995. It can sometimes be abundant after fires (Ross 1957) but the few fires seen onAshdown Forest 1992-1995 have not resulted in any plants, and indeed one site was lost on Old Lodge Reservefollowing the fire in 1994. Quite why it is characteristic of rides is not certain, but it is definitely more frequent onthem than in the surrounding heaths.Dodder is a parasite of plants, mostly on heathland, chalk grassland and coastal habitats. It is totallyparasitic, and is dependent on its hosts for all its nutrients and water, and its "leaves" which lack chlorophyll arereduced to small scales. Seeds germinate in spring after the other vegetation has started to grow, and producefine yellowish threads which circumnutate around until they find a host plant. The thread then spirals around thehost stems producing small papillae which develop into haustoria (the dodder:host interface). The haustoria