Persicaria bistorta (L.) Samp. (= Polygonum
bistorta L. = Bistorta officinalis Delarbre), Common Bistort
Account Summary
Introduced neophyte, a rare garden escape. Eurasian boreo-temperate, but so widely naturalised it has become circumpolar.
1884; Barrington, R.M.; field near shore W of Ely Lodge House.
April to August.
Growth form and preferred habitats
This tall, pink-flowered, rhizomatous garden perennial is definitely a neophyte, introduced alien species in Ireland. In Britain, it is now recognised that the native range is obscured by additional introduced garden forms across the whole country (A.R. Akeroyd, in: Preston et al. 2002). P. bistorta prefers damp, mildly acidic, humus-rich soils, often near water. The most natural habitats it occupies are base-poor, damp soils on river banks, tall-herb communities in river valleys, and mountain ledges. It also occurs in more artificial, man-made habitats, including pastures, hay meadows and roadside verges.
Reproduction
P. bistorta can reproduce and disperse vegetatively, by means of its stout rhizome, and by flowering. The latter takes place from May or June to August, cross-pollination of the perfumed white flowers being carried out by insect visitors, including sawflies (Proctor et al. 1996). Seeds are scattered by birds feeding on the fruiting heads (Grieve 1931). As a result of these reproductive methods, P. bistorta often forms dense clonal clumps that can prove long-persistent.
Fermanagh occurrence
P. bistorta is rarely found in 'the wild' in Fermanagh, having been recorded in just eleven scattered lowland tetrads in the VC. It is most often found in or near demesnes such as Ely Lodge, Castle Coole and Florencecourt, from the gardens and grounds of which it tends to 'escape'. In more recent years, it has also been found by the sides of roads and forest tracks, and at least once near a ruined cottage where it certainly is a relic of cultivation. As a local instance of its persistence, P. bistorta still occurs at, or very close to, Barrington's original 1884 meadow site at Ely Lodge on the shore of Lower Lough Erne.
Fossil record
Fossil pollen of P. bistorta and P. vivipara (L.) Ronse Decr. (= Polygonum viviparum L.) (Viviparous Bistort or Alpine Bistort) cannot be distinguished, but P. bistorta seed is recognisable. It has been recorded once, in E Yorkshire, from zone IV of the Flandrian, the current interglacial period we are living in. This is an early post-glacial zone, called the pre-boreal, approximately dating to just after 10,000 BP (Godwin 1975). If this solitary record is correct, it indicates the presence of P. bistorta well before human immigration and settlement. The species is thus regarded as indigenous in NE England, but elsewhere, and especially in SE England, it is possibly or probably a garden escape.
Irish occurrence
Common Bistort was first recorded in the wild in Ireland in 1746 in Co Waterford (H6). Since the mid-19th century onwards it has always been recognised as an alien of garden origin, "formerly much cultivated", probably as a pot and medicinal herb (Cybele Hibernica 1866). By the end of the 19th century, the plant was being considered an increasingly rare, casual relict of cultivation in much of what is now the RoI (Colgan & Scully 1898; Irish Topographical Botany). Interestingly, the New Atlas map indicates that to this day, over a century later, P. bistorta is very much more frequently found in Ireland north of a line drawn between Sligo and Dundalk. Nevertheless, recently the species has been recorded at two sites in Co Waterford in 1997 and 2001 (Green 2008), and the New Atlas indicates it has been found in a post-1987 hectad in E Cork (H5). These appear to be the only Common Bistort sites discovered in S Ireland for very many years (New Atlas; Cat Alien Pl Ir).
British occurrence
Bistort is always local in Britain and Ireland, but is most frequently found in NW England and in S Scotland. Elsewhere in Britain, it is widespread but very local, with the exceptions of the S and E English Midlands and the Scottish highlands and islands, in both of which it is scarce or absent. With regards the species status, P. bistorta is generally considered native in Cumbria and S Scotland where it is most plentiful, although in truth as time goes on it appears increasingly difficult, if not nigh impossible, to distinguish introduced populations of garden origin from native ones throughout the island (Lousley & Kent 1981; J.R. Akeroyd, in: Preston et al. 2002).
This becomes especially the case when one realises that in the past Bistort was widely cultivated around habitation, not like today for its decorative flower heads, but rather for use as an edible pot herb. It was used as a spring green vegetable, valued for the supposed nutritional quality of its leaves that were reputed to cleanse the blood. It may have had additional herbal medicinal properties (Grieve 1931; Grigson 1987; and see below).
European and world occurrence
P. bistorta is widely distributed and considered native in boreal Europe and W Asia, but in S Europe it becomes mainly confined to the mountains. It is absent as a native in Ireland and in most of Fennoscandia (Jalas & Suominen 1979, Map 414; Tutin et al. 1993). A form known as P. bistorta subsp. plumosum (Small) Hult. occurs in E Siberia and northwestern N America (Hultén & Fries 1986, Map 653). The Siberian distribution remains insufficiently known. The European form of the species has been introduced widely beyond its native range, including to N America, making it now a circumpolar boreo-temperate species.
Names
The genus name 'Persicaria' is from the Latin 'persicum' meaning peach, and translates as either 'peach-leaved' (Gilbert-Carter 1964), or 'peach-like' (Gledhill 1985). The Latin specific epithet 'bistorta' is the Mediaeval or 16th century name of the plant, and it was also previously its generic name (Grigson 1974). It is a combination of two words, 'bis' and 'torta'; it translates as 'twice twisted', a reference to the plant's characteristic stout, contorted rhizome which is often 'S'-shaped (Grieve 1931; Clapham et al. 1962; Gilbert-Carter 1964).
This feature of the plant and its creeping nature appears to be the origin of some of the alternative English common names, which refer to coiled snakes or adders. Early English herbalists including Gerard and Lyte called the plant 'Adderwort' and 'Snakeweed', and by the Doctrine of Signatures, or the principle of sympathetic magic, they regarded it as a remedy for snake bite or poison (Grigson 1987).
Seven of the sixteen English common names from around Britain and Ireland listed by Grigson (1987) refer to some aspect of Easter (eg Easter Ledger, Easter Ledges, Easter Mangiants), or Passion (Passion-tide being Easter), (eg Passion Dock and Patience Dock). The reason for this appears to be that P. bistorta was an ingredient of a food called 'Easter Ledger Pudding' (Grigson 1987).
Uses
In the English Lake District, where today the species is most frequent and abundant, the young springtime leaves are still eaten as a vegetable like spinach and they are used as one ingredient of a traditional Easter pudding with fertility and blood cleansing connotations. Grigson (1955, 1987) provides a detailed and plausible explanation of the mysterious beliefs surrounding this matter, and also details a fascinating symbolic link with the marvellously beautiful 'Captured unicorn' French wedding tapestry of 1514. This seasonal folk use led to the local cultivation of the plant in Cumberland and Westmorland, and it is known there as 'Easter Giants', 'Easter Mangiants', 'Easter Ledges', Easter Ledger', 'Passion Dock' and 'Patience Dock' amongst other names, from which Grigson (1955, 1987) draws meaning.
Additional medicinal folklore and Easter pudding recipes are provided by Vickery (1995) and Mabey (1996). Grieve (1931), and Allen & Hatfield (2004) list medicinal uses of the plant, which is one of the strongest astringents around. It is also highly styptic (ie it stops bleeding), and has been used both as famine food and for the treatment of numerous complaints, including wounds, headaches, worms, and bowel and urinary problems.
Threats
None.