Flora of Ashdown Forest - Botanical Society of the British Isles

CALLlTRICHACEAE151Ca/litriche is a difficult genus whose members are best identified from plants withfruits; useful illustrations are given in Stace (1991). Lack of fruits is usuaJly given asthe reason by most botanists for ignoring this genus, but careful searching of plantsor populations shows that at least some are usually present, and young fruits can bematured on plants in jam jars on window sills. The map shows all Callitriche records.Other than some C. stagna/is, which is the common plant of puddles on rides,virtually all records have been seen or checked by TR, All species are probablyunder-recorded in Sussex and Britain,Callitriche stagna/is. Common water-starwort.Common on the Forest (Hall 1980).Common on wet rides in damp muddy depressions as an annual, andoccasionally in water. Plants on the rides disappear by the end of the summer butcan be found germinating in spring so there must be a seed bank in the mud.3 Common in the Weald and widespread in Britain, the commonest species.Widespread in most of western Europe and North Africa.4 5Callitriche platycarpa. Various-leaved water-starwort.Ditches on old railway line, Forest Row (43.34 and 44.34), PW & TR, 1995.These tend to be bigger more robust plants than C. stagna/is and have long,obvious stamens if you can find them flowering. Grime et al. (1988) note it mayreplace C. stagnalis in lowland waters enriched by agricultural run-off.3 There are few Sussex records and it may indeed be quite uncommon. Probablywidespread in lowland Britain. Possibly endemic to north-west and central Europe.4 5Callitriche obtusangula. Blunt-fruited water-starwort.Lake at Forest Row 1421.346); lakes and streams at Pippingford Park 144.30, 45.31);scattered down the stream running through Newbridge, and present as large mats inthe water-splash 1455.325); stream by bridge, Hart's Farm 1461.332), all 1995, TR.Usually in streams in more base-rich water and flowering/fruiting later than the3 other species. It is rarely recorded in Sussex but is surely widespread and is commonin the fen areas of east Kent. Probably widespread in southern Britain, southern andwestern Europe and North Africa.4 5Callitriche hamulata. Intermediate water-starwort.Pond on Ashdown Forest near Wych Cross IWhitwell 1902). Occasional on theForest IHall 1980).Frequent in ponds and standing water which is clear and probably fairly acidicand nutrient-poor. Linear-leaved masses in the Medway seem to be this species, butgrow mixed with an unidentified broad-leaved species.Occasional in Sussex, and probably widespread in lowland Britain. Possiblyendemic to north-west and central Europe.4 5