45.) POLYGONACEAE - Knotweed family - Pages

45.) POLYGONACEAE - Knotweed family

POLYGONACEAE - Knotweed family

PERSICARIA Mill.

Persicaria amphibia (L.) Delarbre (Amphibious Bistort) / Wetland Uncommon Widespread and locally frequent in and besides ponds, lakes, rhynes, slow-moving rivers and marshy meadows; most concentrated around the coastal lowlands, the North Somerset Levels and Moors and around Chew Valley Lake. It is often encountered in its terrestrial state which looks remarkably different to when it's growing submerged in water and this led past botanists to class it as a separate variety - var. terrestre. In this form it can carpet huge areas by rhizomatous spread but rarely produces flowers and is often seen growing on the sides of roads, amongst hedges and wet corners of fields; even occasionally found at quite a distance from water sources. The earliest local record was made at St Anne's Wood, Brislington in 1834 by G.W. Braikenridge - a famous Bristolian antiquarian who created a large collection of historical and topographical material known as the 'Braikenridge Collection' (now in the possession of BMAG); containing over 1400 drawings and watercolours of Bristol landscapes and buildings.

Persicaria maculosa Gray (Redshank) / General Common A common species of disturbed ground such as roadsides, arable fields, gateways, spoil heaps and along urban streets and kerbsides but also found in a more natural state on the margins of ponds and along the banks of watercourses; becoming scarce in areas of higher elevation.
Persicaria lapathifolia (L.) Delarbre (Pale Persicaria) / General Frequent Found in much the same situations as Redshank and often with it but not as frequent. Very variable in appearance - ranging from large and robust with drooping almost white inflorescences to upright, pink and close in aspect to Redshank. It differs though, ultimately in the frequent presence of glands in the upper parts (absent of rare in P. maculosa). White (1912) gives Glandular Persicaria as an alternative name.

It differs though, ultimately in the frequent presence of glands in the upper parts (absent of rare in P. maculosa), the seeds being mostly biconcave to plano-concave rather than biconvex to plano-convex and the veins of the outer tepals being divided with the branches turned back distally as oppose to undivided or divided with forward-directed branches (Stace, 2021).

Persicaria pensylvanica (L.) M. Gómez (Pinkweed) General Extinct A native of eastern North America; only recorded on two occasions: at Avonmouth Docks in 1959 by ? [BMAG] and on Soyabean waste at Royal Portbury Dock in 1994 by R.J. Higgins.
Persicaria hydropiper (L.) Delarbre (Water-pepper) / Wetland Uncommon Locally frequent in ponds, marshes, besides watercourses and along damp woodland rides; most plentiful around the North Somerset Levels and Moors, around Chew Valley and in the north of the region between Oldbury-on-Severn and Hill. One of the most fun plants to identify in the act of passing a piece to an unsuspecting newcomer and observing their reaction. It starts off tasteless but after a few seconds a sharply peppery bitter taste is detected and continues to build with increasing intensity until it must be spat out - followed by the desperate scrambling attempt to find something to take the taste away!

The act of passing a piece to an unsuspecting newcomer to taste can be amusing to observe their reaction. It starts off tasteless but after a few seconds a sharply peppery bitter taste is detected and continues to build with increasing intensity until it must be spat out - followed by the desperate scrambling attempt to find something to take the taste away!

Persicaria mitis (Schrank) Assenov (Tasteless Water-pepper) Wetland Extinct Only recorded three times in our region: On the "Bank of the Chew at Compton Dando, 1895." (White, 1912 [as Polygonum mite]); at Nailsea Moor in 1984 by E.S. Smith; and at ST67 in 1990s by ? [BSBI record]. White (1912) gives Lax-flowered Persicaria and Riddelsdell (1948) gives Loose-flowered Persicaria as alternative names. It should be sought after and can be distinguished from P. hydropiper by the lack of a peppery taste, the more erect inflorescences and purplish-pink flowers. The achenes also have a smooth shiny surface (minutely punctate and dull in P. hydropiper).

It should be sought after and can be distinguished from P. hydropiper by the lack of a peppery taste, the more erect inflorescences and purplish-pink flowers, the achenes with a smooth shiny surface (minutely punctate and dull in P. hydropiper), the perianth often (but not always) without glands and the the hairs on the surface of the stipules being fused for less than 3/4 of the length (fused for most of the length in P. hydropiper).

Persicaria minor (Huds.) Opiz (Small Water-pepper) 1921 Wetland Extinct Formerly occurred at "Yate Common; in two wet, boggy hollows; plentiful in one and sparingly in another...Discovered by C. Bucknall in Sept. 1909." (White, 1912). Also found at Nailsea Moor in 1921 by N.Y. Sandwith and again in 1948 by C.I. & N.Y. Sandwith.

[Also a pre-1930s BSBI record from ST55 which might be in our region - check!].

Persicaria capitata (Buch.-Ham. ex D. Don) H. Gross (Pink-headed Persicaria) General Rare A rare casual introduction; sometimes grown in gardens and escapes onto pavements and at the bases of walls. Recorded for the first time in our region at Thornbury in 2000 by C. & M.A.R. Kitchen; Codrington, South Gloucestershire in 2006 by C. & M.A.R. Kitchen; Portishead Dock in 2013 by C.M. Lovatt; there again in 2016 by R.J. Higgins [most recently seen in 2020s by ? - BSBI record]; ST57E in 2010s by ?; ST57W in 2010s by ? [BSBI records]; Bishopston, Bristol in 2020 by R.J. Higgins; Bath in 2020s by ? [BSBI record]; in a gateway entrance and on a kerbside on Cornwall Road, Bishopston, Bristol in 2025 by D. Peters; and a large patch was found trailing out of the harbourside at Cumberland Basin in 2026 during a BNS New Year Plant Hunt.

[Perhaps only need to mention first record.]

KOENIGIA L.

Koenigia polystachya (Wall. ex Meisn.) T.M. Schust. & Reveal (Persicaria wallichii Greuter & Burdet) (Himalayan Knotweed) General Extinct A very rare established introduction; found along the banks of watercourses, on roadsides, railway lines and derelict ground. First recorded among bushes near Ladye Bay, Clevedon in 1943 by C.I. Sandwith and only recorded twice since 2000: at Winterbourne Down in 2003 by R. Bland and near an allotment at Ashton Gate in 2004 also by R. Bland.

BISTORTA Adans.

Bistorta officinalis Delarbre (Persicaria bistorta (L.) Samp.) (Common Bistort) / General Very Rare A very rare native in our area; found predominantly in damp grassland, hedge bottoms and woodland rides. It has declined significantly since White's time. It is also widely planted around newly made ponds and lakes and some records may have obscured its known native distribution. Otherwise known as Snakeweed.
Bistorta amplexicaulis (D. Don) Greene (Persicaria amplexicaulis (D. Don) Ronse Decr.) (Red Bistort) / General Very Rare A rare introduction; widely grown for ornament and often used in public planting displays and sometimes escapes. It is now well-established in some places. First noticed in our area from Burrington Combe in the 1950s according to the Flora of the Bristol Region (2000).

FAGOPYRUM Mill.

Fagopyrum esculentum Moench (Buckwheat) / General Scarce An infrequent casual; sometimes occurring as a birdseed alien or introduced with spoil on newly made ground. It is often used in mixes sown for pheasant feed and is sometimes a contaminant of ornamental seed mixes. It is also often grown as a green manure and may be of regular occurrence around allotments.
Fagopyrum tataricum (L.) Gaertn. (Green Buckwheat) 1932 General Extinct A native of Asia; recorded on a rubbish-tip at Horfield in 1917; Ashton Gate in 1924; and Bedminster in 1932 by C.I. Sandwith; and at Avonmouth Docks in 1936 by ? [BMAG].

POLYGONUM L.

Polygonum maritimum L. (Sea Knotgrass) 1856 Coasts Extinct This plant "was stated by Dr. St. Brody to occur, rarely, on the beach at Weston-super-Mare; but of this there has been no confirmation." (White, 1912). A number of St. Brody's records mentioned in his list produced in 1856 were met with skeptisism at the time but many have since proven to be true.
Polygonum corrigioloides Jaub. & Spach (find common name! - Corrigioloid Knotgrass?, Strap Knotgrass?, Strapwort Knotgrass?) 1926 General Extinct A native of the Middle East; recorded at Bedminster in 1926 by C.I. Sandwith and compared at Kew - a first and only record for the British Isles.
Polygonum cognatum Meisn. (ssp. cognatum) (Indian Knotgrass) 1981 General Very Rare A native of Asia; recorded on Cranbrook Road, Redland in 1922 by H.S. Thompson. Recently a single plant was found at Yate in 2025 by C. & M.A.R. Kitchen.

[Yate record was said to me in person.]

Polygonum oxyspermum C.A. Mey. & Bunge ssp. raii (Bab.) D.A. Webb & Chater. (Ray's Knotgrass) - Coasts Very Rare Very rare on the sand dunes at Sand Bay where it occurs intermittently. First discovered here in 1986 by A. Coles. Also recorded historically on the "Shore, New Passage, July 1865, Herb. St. Brody." (White, 1912).
Polygonum arenastrum Boreau (Equal-leaved Knotgrass) / General Common Common in the cracks of pavements, trampled bare ground in amenity spaces and on cultivated ground. Not separated from P. aviculare until relatively recently. First recorded in our region at Avonmouth in 1928 by C.I. Sandwith (Riddelsdell, 1948 [as P. aequale]).
Polygonum aviculare L. (Knotgrass) / General Very Common Abundant throughout the region in disturbed and cultivated places; being particularly ubiquitous besides paths, in field entrances and in the dried up muddy puddles of heavily trampled amenity areas. Wire-grass is a local Gloucestershire name according to Riddelsdell (1948).
Polygonum boreale (Lange) Small (Northern Knotgrass) General Very Rare Several plants of this species, traditionally associated with the Scottish coastline, were discovered on a site of recent roadworks at Horfield Common, Bristol in 2023 by D. Peters - the first time this species has been recorded in Britain outside of Scotland - where from it must have been introduced with materials from the works. It is distinguished from the common P. aviculare by its larger obovate leaves with petioles distinctly exserted from the stipules (ovate to elliptic and petioles included in P. aviculare).
Polygonum rurivagum Jord. ex Boreau (Cornfield Knotgrass) - General Scarce A scarce plant of arable fields and disturbed ground; mostly occurring on lighter free-draining soils in the east of the region. Although typically associated with the arable landscape; two records of interesting note have been made at Blaise Castle, Bristol by D. Peters where it occurs in a pond prone to drying and to the side of a trampled path. It is possibly overlooked for P. aviculare and is told by its upright growth with slender leaves and its narrowly oblong tepals which gape near the apex to reveal the achene (less erect, leaves broader with tepals oblong-obovate and overlapping to conceal the achene in P. aviculare).
Polygonum bellardii All. (P. patulum auct. non M. Bieb.) (Red-knotgrass) 1930 General Extinct A native of southern and central Europe; recorded at St. Philip's in 1904 by J.W. White [not mentioned in his flora but in Sandwith, 1932 (as P. patulum)]; Baptist Mills and Avonmouth Docks in 1925 by C.I. Sandwith; there again in 1928 by H.J. Gibbons; Ashton Gate in 1930 by C.I. Sandwith; and last seen at Shirehampton in 1960s by ? [BSBI record].

[Also a 1930 record from Bedminster which needs checking in BMAG as it is only mentioned under the next species in Sandwith (1932).]

Polygonum arenarium Waldst. & Kit. ssp. pulchellum (Loisel) Thell. (Lesser Red-knotgrass) 1930 General Very Rare A native of the Mediterranean; recorded at Bedminster in 1930 and Baptist Mills in 1931 by C.I. Sandwith; Manor Farm, Thytherington in 1956 by Thornbury County Secondary School; and more recently in several places around Cotham, Bristol in 1999 by ?; in 2000 by ?; and again in 2002 by M. English; Batheaston in 2001 by ?; and at Tyntesfield in 2005 by H.J. Crouch.

[I am suspicious of these Cotham records. Could they be an error for P. arenastrum? - check all records since 1956.]

FALLOPIA Adans.

Fallopia baldschuanica (Regel) Holub (Russian-vine) / Woodland Uncommon An aggressive invasive climber grown in gardens and frequently escaping. It is often found carpeting over scrub, hedgerows, the tops of trees, and along railway banks and roadsides; sometimes covering huge areas as at Coombe Dingle, Bristol where it was found covering along around 100 m of woodland beside Dingle Road opposite between Dinglewood Close and Coombe Lane in 2022 by D. Peters. It was first discovered here in 1980 by W.G.D. Shaw.
Fallopia convolvulus (L.) Á. Löve (Black-bindweed) /- General Frequent A frequent species of arable fields, spoil heaps and newly made ground.
var. convolvulus General Frequent The nominate plant with the outer tepals keeled.
var. subalatum (Lej. & Courtois) D.H. Kent General [Brist. Fl. & Glos. Fl.] General Scarce With winged outer tepals. According to White (1912) this variety "seems to be frequent in hedges and thickets".
Fallopia dumetorum (L.) Holub (Copse-bindweed) 1933? / - Woodland Very Rare Discovered amongst Bracken scrub at Backwell, Nailsea in 2014 by C.M. Lovatt and L. McDonald and still present when visited in 2022 by Somerset Rare Plants Group though it is characteristically very intermittent in appearance. Historically occurred "'On the bushy side of a hollow through which the Western Railroad passes, about one mile from Keynsham towards Bristol, and near a bend in the river, Sept. 1831;' C.C. Babington" (White, 1912).

REYNOUTRIA Houtt.

Reynoutria japonica Houtt. (Fallopia japonica (Houtt.) Ronse Decr.) (Japanese Knotweed) / General Frequent A non-native invasive; well-established throughout the region, particularly along the banks of rivers and along railway lines where it can form huge colonies. Most concentrated around Bristol. It is famously portrayed for being able to grow through buildings and being nearly impossible to eradicate. It is not as problematic as it is in other parts of the country. First noted being "Established between Shirehampton and Avonmouth" in 1931 by C.I. Sandwith (Sandwith, 1932 [as Polygonum cuspidatum]).

Fallopia japonica 1st is 1972 East Wood, In clearing which has regrown from bare earth. Anon (I'll put that on the To Do list to try and work out more details).

var. japonica General Frequent The nominate plant to which most records refer. All plants are female and it can only spread by vegetative means.
var. compacta (Hook. f.) Buchheim General Extinct A dwarf form. Recorded at Arnos Vale in 1945 by I.W. Evans.
Reynoutria japonica x R. sachaliensis = R. x bohemica Chrtek & Chrtková (Fallopia japonica x F. sachaliensis = F. x bohemica (Chrtek & Chrtková) J.P. Bailey) (Bohemian Knotweed) General A rare introduction; thinly scattered over the region. Only recorded several times in recent years. First recorded at Shirehampton in 1986 by I.F. Gravestock.
Reynoutria sachaliensis (F. Schmidt) Nakai (Fallopia sachaliensis (F. Schmidt) Ronse Decr.) (Giant Knotweed) General A rare introduction on roadsides and derelict ground. first recorded at Bucklands, Nailsea in 1985 by E.S. Smith.

RHEUM L.

Rheum rhaponticum x R. palmatum = R. x rhabarbarum L. (R. x hybridum Murray) (Rhubarb) - General Widely grown in gardens and on allotments. Occasionally persisting as a relic or garden throwout.

Rheum palmatum x rhaponticum = R. x hybridum 13 records 1st 1998 Cleaves Wood Ian Green Other 1998 Lower Weston Ian Green, Lower Knowle Stuart Hedley, Braysdown ? dumped Rob Randall

RUMEX L.

Subgenus ACETOSA (Mill.) Reich. f.

Rumex acetosella L. (Sheep's Sorrel) / Grassland Uncommon Locally frequent in dry acidic grassland, heaths and exposed rocky habitats; absent from . Few records have been made at the subspecies level.
ssp. acetosella Grassland Uncommon The nominate plant with tepals that are loose and easily rubbed off the ripe achene. Appears to be widely distributed.

[Records need checking to see if any show evidence of identification and not just presumed to be this ssp. as this is thought to be a more northern plant and I'm yet to encounter it.]

ssp. pyrenaicus (Pourr.) Akeroyd Grassland Uncommon From field observations, the majority of our Rumex acetosella appears to be this - with tightly adherent tepals which are not easily rubbed off the ripe achene. Two records of particular interest were made in urban areas in Bishopston, Bristol in 2025 by D. Peters - one well established in between paving in a front garden on Radnor Road and another at the base of a wall on Ash Road. Presumably both instances were introduced with sand or other materials. First recorded in our region on a railway embankment at Ashley Hill, Bristol in 1936 by C.I. Sandwith.

As far as is known, all our plants refer to this rather than the nominate ssp. acetosella from which it differs in having tightly adherent tepals which are not easily rubbed off the ripe achene (loose and easily rubbed off in ssp. acetosella).

Rumex scutatus L. (French Sorrel) 1958 General Very Rare A native of central and southern Europe which is sometimes cultivated as a salad crop; recorded at Saltford in 1866 by ? [I.P. Green, From SERC]; "On an old wall, Clifton, Mrs Bell...Probably at Tortworth, and recorded wrongly as Oxyria" (Riddelsdell, 1948)" [also on BSBI]; Backwell, Nailsea in 1958 by ? [I.P. Green, From SERC]; and more recently at Peasedown St. John, North Somerset in 2007 by ?; and Upper Swainswick (ST76P) in 2020s by ? [BSBI record].
Rumex acetosa L. (Common Sorrel) / Grassland Common Common in almost any grassy situation and tolerating high levels of nutrient enrichment. The leaves taste a bit like apple peal. This along with R. acetosella, is the larval food plant of the Small Copper butterfly (Lycaena phlaeas).
ssp. acetosa Grassland Common The nominate plant with the same range and distribution as the species.
ssp. hibernicus (Rech. f.) Akeroyd (Irish Sorrel) Grassland Very Rare Recorded at Greylands Farm, East Dundry in 2002 by P. Quinn.

[Record is almost certainly wrong. Possibly it was var. hirtulus.]

ssp. ambiguus (Gren.) Á. Löve (R. rugosus Campd.) (Garden Sorrel) - 1 BSBI Record General Very Rare Grown as a salad plant. It was recorded at Bristol in 2010s by ? [BSBI record].

Subgenus RUMEX

Rumex salicifolius Weinm. ssp. triangulivalvis Danser (R. triangulivalvis (Danser) Rech. f.) (Willow-leaved Dock) [Sandwith, 1932] General Extinct A native of North America; introduced with grain. First recorded at Baptist Mills in 1917 by C.I. Sandwith; "It has since been increasingly frequent at Bristol and Avonmouth." (Sandwith, 1932). Also "collected by J. P. M. Brenan at Ashley Hill in 1936." (Riddelsdell, 1948) and last recorded at ST57 in 1960s by ? [BSBI record].
Rumex cuneifolius Campd. (Argentine Dock) [Sandwith, 1932] General - [on DB as R. frutescens] Coasts Very Rare A native of South America; first recorded at Avonmouth Docks in 1923 by C.I. Sandwith and again in 1934 by ?; at ST47 in 1940s by ? [BSBI record]; and at Uphill in 2015 by ? (most recently seen here in 2020s by ? [BSBI record]).
Rumex alpinus L. (Monk's-rhubarb) General Extinct A native of continental Europe; recorded at Tickenham in 1984 by E.S. Smith.
Rumex aquaticus × R. crispus = R. x conspersus Hartm. (Scottish x Curled Dock) - [Sandwith, 1932] General Extinct Recorded at Portishead Docks in 1908 by I.M. Roper.

[This needs investigating! Seems highly unlikely as R. aquaticus only grows in a restricted part of Scotland. Sandwith (1932) gives in brackets a completely different combination of R. domesticus x obtusifolius which is less unlikely but R. domesticus (now R. longifolius) also only grows in the north. If it is that then the correct name would be R. x hybridus. The record is not mentioned in White (1912) and no more can be found of it. Sandwith puts an asterisk next to it, indicating she hasn't actually seen the specimen. A more likely possibility is that a nomenclatural mistake has been made and possibly what was really intended was R. hydrolapathum x R. obtusifolius = R. x weberi. It is easy to slip up and instinctive to think Water Dock must be R. aquaticus? or possibly it was a naming error for the similar sounding R. confertus (Russian Dock). Lousely (1938, p. 150) says it might have been R. stenophyllus].

Rumex hydrolapathum Huds. (Water Dock) / Wetland Scarce Our largest Dock species; found besides watercourses and in floodplains. It is particularly abundant along parts of the tidal Avon and around the North Somerset Levels and Moors. It is also sometimes planted besides ponds.
Rumex hydrolapathum x R. obtusifolius = R. x weberi Fisch.-Benz. (R. x lingulatus Jungner) (Water x Broad-leaved Dock) Wetland Extinct Recorded on a rhyne bank near Hutton, North Somerset in 1988 by I.F. Gravestock and determined by J.R. Akeroyd. Also recorded at ST57 in pre-1930 by ? [BSBI record]. It is likely to be overlooked.
Rumex cristatus DC. (Greek Dock) Coasts Very Rare A native of south-eastern Europe; established at Sand Bay where it was first recorded in 1995 by D. Maxwell and confirmed by I.P. Green. It has since also been found further down the coast at Weston-super-Mare in 2019 by J. Mortin.
Rumex cristatus x R. crispus = R. x dimidiatus Hausskn. (Greek x Curled Dock) Coasts Extinct Was recorded at Sand Bay in 1995 by I.P. Green.
Rumex patientia L. (Patience Dock) General Extinct A native of continental Europe and Asia. See subspecies for details.
ssp. orientalis Danser General Extinct Native to eastern Europe and South Asia. Found on Ebenezer Lane, Stoke Bishop, Bristol in 1987 by I.F. Gravestock.

[Need to check this as only recorded at species level but it is the more common taxon.]

ssp. patientia (Patience Dock) [Glos. Fl.] General Extinct The nominate plant with purplish stems and a smaller perianth; native to south central Europe. Recorded on Cranbrook Road, Redland, Bristol in 1926 by H.J. Gibbons; and Avonmouth Docks in 1928 by C.I. Sandwith.
Rumex stenophyllus Ledeb. (Narrow-leaved Dock) [Glos. Fl.] General Extinct A native of central and eastern Europe; was found to be naturalised at Avonmouth Docks in 1938 by J.E. Lousely [B.E.C., 1938, p. 149-50].
Rumex crispus L. (Curled Dock) / General Common Widespread and frequent in disturbed grassy places. See subspecies for details.
ssp. crispus General Common The nominate plant with small unequal tubercles (less than 2.5 mm) and usually only one developing; same range and distribution as the species.
ssp. littoreus (J. Hardy) Akeroyd. (Curled Dock) / Coasts Scarce With larger tubercles which are similar in size and dense inflorescences. Found all along the coast in dunes, upper saltmarsh, and particularly prominent on shingle.
ssp. uliginosus (Le Gall) Akeroyd. (Curled Dock) Wetland Scarce With tubercles like ssp. littoreus but a much taller plant and with lax inflorescences. Found in muddy estuaries and along the banks of the tidal Avon. First recorded in 1980 by C.M. Lovatt.
Rumex crispus x R. conglomeratus = R. x schulzei Hausskn. (Curled x Clustered Dock) General Extinct Recorded at Avonmouth Docks in 1939 by ? [BMAG] and at Clevedon in 1990s by ? [BSBI record]. It is probably overlooked.
Rumex crispus x R. sanguineus = R. x sagorskii Hausskn. (Curled x Wood Dock) /- General Very Rare Recorded at Norton, Weston-super-Mare and east of Woolvers Hill, North Somerset in 1992 by A.G. Smith; and at Thornbury in 2020s by ? [BSBI record]. It is probably overlooked.
Rumex crispus x R. obtusifolius = R. x pratensis Mert. & W.D.J. Koch (Curled x Broad-leaved Dock) /- General Uncommon The most common Dock hybrid; widely scattered over the region where ever the two parents meet.

[There are many more records on BSBI.]

Rumex crispus x R. obovatus = R. x bontei Danser (Curled x Obovate-leaved Dock) - [Bristol Botany in 1935] General Extinct Recorded at Avonmouth Docks in 1928 by C.I. & N.Y. Sandwith [B.E.C., 1935, p. 40].
Rumex conglomeratus Murray (Clustered Dock) / Wetland Frequent A frequent species of damp marshy ground, wet grassland, pond-sides, ditches banks and open woods. Sometimes found in drier situations on heavy soils. It is particularly abundant along the coastal strip. White (1912) and Riddelsdell (1948) give Sharp Dock as an alternative name.
Rumex conglomeratus x R. sanguineus = R. x ruhmeri Hausskn. (Clustered x Wood Dock) General Extinct Recorded at BAJ engineering works, Hutton, North Somerset in 1990 by E.J. McDonnell and at Cleveedon in 1990s by ? [BSBI record]. Both species frequently occur together and it is almost certainly overlooked.
Rumex conglomeratus x R. pulcher = R. x muretii Hausskn. (Clustered x Fiddle Dock) General Extinct Recorded with both parents by a track near the Old Church, Clevedon in 1921 by C.I. Sandwith.
Rumex conglomeratus x R. obtusifolius = R. x abortivus Ruhmer (Clustered x Broad-leaved Dock) General Very Rare Recorded in a damp area adjacent to a stream, west of Faulkland Lane, south of Stoney Littleton in 1997 by I.P. Green; and at Midsomer Norton in 2013 by P.R. Green.
Rumex sanguineus L. (Wood Dock) / Woodland Common Common in woodland, along hedgebanks and more in the open in rough grassland, along verges and besides waterways.
var. viridis Sibth. Woodland Common The nominate plant with the same range and distribution as the species.
var. sanguineus (Blood-veined Dock) / General Rare A conspicuously marked plant with deep blood-red veining. It sometimes escapes cultivation onto pavements and kerbsides. It seems to be particularly well-naturalised around Bishopston, Bristol.

[Could the Lord's Wood plant be native?]

Rumex sanguineus x R. obtusifolius = R. x dufftii Hausskn. (Wood x Broad-leaved Dock) General Rare The second most frequent Dock hybrid in the region; sparsely scattered over the region. It is still probably overlooked.
Rumex pulcher L. (Fiddle Dock) /- Grassland Uncommon A plant of well-drained grassland; particularly where the ground is bare. It is named after its distinctive fiddle-shaped or 'panduriform' leaves.
ssp. pulcher Grassland Uncommon The nominate plant with the same range and distribution as the species.
ssp. woodsii (De Not.) Arcang. (ssp. divaricatus (L.) Murb.) (Fiddle Dock) 1942 [Glos. Fl.] General Extinct Recorded at Ashton Gate in 1939 by C.I. Sandwith. "Adventive material from the docks frequently belongs to foreign subspecies, such as subsp. divaricatus...which was collected at Wapping Wharf, Bristol, July 1940, by J. P. M. Brennan." (Riddelsdell, 1948).
Rumex pulcher x R. obstusifolius = R. x ogulinensis Borbás (Fiddle x Broad-leaved Dock) General Extinct Recorded at Tickenham in 1940 by C.I. Sandwith. It is probably overlooked.
Rumex obtusifolius L. (Broad-leaved Dock) / General Very Common Abundant throughout the region on any ground rich in nutrients.
var. obtusifolius General Very Common The nominate plant with large tepals bearing strong teeth and one tubercle; same range and distribution as the species.
ssp. subalpinus (Schur) Čelak. Was apparently recorded at Avonmouth Docks [B.E.C. 1938, p. 128] - need to check Bristol Museum [Glos. Fl.] - A native of the Balkan peninsula, Turkey and the Caucasus "has leaves glabrous or minutely papillose-scabrid beneath, and valves narrowly triangular, subacute, with several teeth, one valve with a tubercle" (Akeroyd, 2014). "There is no definite evidence of the occurrence of this subspecies in Britain. On specimens...from...Avonmouth Docks...Reichinger wrote as follows: - '...gatherings recall the ssp. subalpinus from S.E. Europe but could be quite as well an unusually small fruited form of ssp. agrestis [var. obtusifolius]'. The material was gathered late and was obviously not good enough for a stable determination of a critical plant." (Lousley in B.E.C., 1938, p. 128). General
Rumex dentatus L. (Aegean Dock) 1928 General Extinct A former casual. See subspecies for details.

[Also found at Avonmouth Docks in 1923 by ? and Ashton Gate in 1939 by ? [BMAG] - need to find out which subspecies they belong to.]

ssp. halacsyi (Reich.) Reich. f. General Extinct [Sandwith, 1932] A native of the eastern Mediterranean and the Middle East; recorded at Avonmouth Docks in 1931 by C.I. Sandwith and determined by Danser. Also found there in 1938 by J.P.M. Brenan (Riddelsdell, 1948).
ssp. klotzschianus (Meisn.) Rech. f. General Extinct [Sandwith, 1932] A native of south Asia; recorded at Baptist Mills from 1925-26 and Bedminster in 1928 by C.I. Sandwith and determined by Danser.
Rumex obovatus Danser. (Obovate-leaved Dock) [Sandwith, 1932] General Extinct A native of South America; recorded at Eastville in 1920 by C.I. Sandwith; and at Avonmouth Docks in 1928 by C.I. Sandwith and H.J. Gibbons [BMAG]. Last recorded here in 1960s by ? [BSBI record].
Rumex palustris Sm. (Marsh Dock) 1941 Wetland Very Rare A plant of marshland. Recorded at Nailsea Moor in 1921 and 1958 by C.I. Sandwith; Dolbury Warren in 2000 by R.J. Higgins; Locking Road, Weston-super-Mare (Donkey Field) in 2004 by S. Griffin; Fields West of Littlewood Lane in 2004 by L. Moore; and most recently at ST57I in 2010s by ? [BSBI record].
Rumex maritimus L. (Golden Dock) - Wetland Very Rare A very rare species; found on the muddy margins of ponds and cattle-trodden fields in the north of the region around Hill where it was first discovered in 1984 by C. & M.A.R. Kitchen and also around Chew Valley Lake where it was discovered in the same year by J.P. Martin. It was also recorded along the tidal Avon at ST57I and ST57M in 2010s by ? [BSBI records]. Historically also recorded at Nailsea Moor in 1941 by C.I. Sandwith.

List:

Persicaria amphibia (L.) Delarbre (Amphibious Bistort) / Wetland
Persicaria maculosa Gray (Redshank) / General
Persicaria lapathifolia (L.) Delarbre (Pale Persicaria) / General
Persicaria pensylvanica (L.) M. Gómez (Pinkweed) General
Persicaria hydropiper (L.) Delarbre (Water-pepper) / Wetland
Persicaria mitis (Schrank) Assenov (Tasteless Water-pepper) Wetland
Persicaria minor (Huds.) Opiz (Small Water-pepper) 1921 Wetland
Persicaria capitata (Buch.-Ham. ex D. Don) H. Gross (Pink-headed Persicaria) General
Koenigia polystachya (Wall. ex Meisn.) T.M. Schust. & Reveal (Stace) Persicaria wallichii Greuter & Burdet (NBN) (Himalayan Knotweed) General
Bistorta officinalis Delarbre (Stace) Persicaria bistorta (L.) Samp. (NBN) (Common Bistort) / General
Bistorta amplexicaulis (D. Don) Greene (Stace) Persicaria amplexicaulis (D. Don) Ronse Decr. (NBN) (Red Bistort) / General
Fagopyrum esculentum Moench (Buckwheat) / General
Fagopyrum tataricum (L.) Gaertn. (Green Buckwheat) 1932 General
Polygonum maritimum L. (Sea Knotgrass) 1856 Coasts
Polygonum corrigioloides Jaub. & Spach (find common name! - Corrigioloid Knotgrass?, Strap Knotgrass?, Strapwort Knotgrass?) 1926 General
Polygonum cognatum Meisn. (ssp. cognatum - Kew, GBIF) (Indian Knotgrass - Stace, NBN, Indian Knotweed - old flora) 1981 General
Polygonum oxyspermum C.A. Mey. & Bunge (ssp. raii (Bab.) D.A. Webb & Chater. - Stace) (Ray's Knotgrass) - Coasts
Polygonum arenastrum Boreau (Equal-leaved Knotgrass) / General
Polygonum aviculare L. (Knotgrass / General
Polygonum boreale (Lange) Small (Northern Knotgrass) General
Polygonum rurivagum Jord. ex Boreau (Cornfield Knotgrass) - General
Polygonum bellardii All. (Stace) Polygonum patulum auct. non M. Bieb. (NBN) (Red-knotgrass) 1930 General
Polygonum arenarium Waldst. & Kit. ssp. pulchellum (Loisel) Thell. (Lesser Red-knotgrass) 1930 General
Fallopia baldschuanica (Regel) Holub (Russian-vine) / Woodland
Fallopia convolvulus (L.) Á. Löve (var. convolvulus - Stace, NBN) (Black-bindweed) /- General
Fallopia convolvulus (L.) Á. Löve var. subalatum (Lej. & Courtois) D.H. Kent (Black-bindweed) [Brist. Fl. & Glos. Fl.]
Fallopia dumetorum (L.) Holub (Copse-bindweed) 1933? / - recorded in 2014 at Nailsea by Clive Lovatt and Liz McDonald Woodland
Reynoutria japonica Houtt. (var. japonica & var. compacta (Hook. f.) Buchheim - Stace) Fallopia japonica (Houtt.) Ronse Decr. (NBN) (Japanese Knotweed) / General
Reynoutria japonica x R. sachaliensis = R. x bohemica Chrtek & Chrtková (Stace) Fallopia japonica x F. sachaliensis = F. x bohemica (Chrtek & Chrtková) J.P. Bailey (NBN) (Bohemian Knotweed - Stace) General
Reynoutria sachaliensis (F. Schmidt) Nakai (Stace) Fallopia sachaliensis (F. Schmidt) Ronse Decr. (NBN) (Giant Knotweed) General
Rheum rhaponticum x R. palmatum = R. x rhabarbarum L. (Stace) R. x hybridum Murray (NBN) (Rhubarb) - General
Rumex acetosella L. ssp. pyrenaicus (Pourr.) Akeroyd (Sheep's Sorrel) / Grassland
Rumex scutatus L. (French Sorrel) 1958 General
Rumex acetosa L. ssp. acetosa (Common Sorrel) / Grassland
Rumex acetosa L. ssp. hibernicus (Rech. f.) Akeroyd (Irish Sorrel) Grassland - [record is almost certainly wrong.]
Rumex acetosa L. ssp. ambiguus (Gren.) Á. Löve (R. rugosus Campd. - Kew, GBIF) (Garden Sorrel) - 1 BSBI Record General
Rumex salicifolius Weinm. (ssp. triangulivalvis Danser - Stace) (R. triangulivalvis (Danser) Rech. f. - Kew, GBIF) (Willow-leaved Dock) [Sandwith, 1932] General
Rumex cuneifolius Campd. (Rumex frutescens Thouars - NBN) (Argentine Dock) [Sandwith, 1932] General
Rumex alpinus L. (Monk's-rhubarb) General
Rumex aquaticus × R. crispus = R. x conspersus Hartm. (Scottish x Curled Dock) - seems highly unlikely as R. aquaticus only grows in a restricted part of Scotland. Sandwith (1932) gives in brackets a completely different combination of R. domesticus x obtusifolius which is less unlikely but R. domesticus (now R. longifolius) also only grows in the north. If it is that then the correct name would be R. x hybridus. The record is not mentioned in White (1912) and no more can be found of it. Sandwith puts an asterisk next to it, indicating she hasn't actually seen the specimen. A more likely possibility is that a nomenclatural mistake has been made and possibly what was really intended was R. hydrolapathum x R. obtusifolius = R. x weberi. It is easy to slip up and instinctive to think Water Dock must be R. aquaticus? or possibly it was a naming error for the similar sounding R. confertus (Russian Dock) [Sandwith, 1932] General
Rumex hydrolapathum Huds. (Water Dock) / Wetland
Rumex hydrolapathum x R. obtusifolius = R. x weberi Fisch.-Benz. (Stace, NBN) R. x lingulatus Jungner (old name) (Water x Broad-leaved Dock) Wetland
Rumex cristatus DC. (Greek Dock) Coasts
Rumex cristatus x R. crispus = R. x dimidiatus Hausskn. (Greek x Curled Dock) Coasts
Rumex patientia L. (ssp. orientalis Danser - Stace, NBN) (Patience Dock) General
Rumex patientia L. ssp. patientia (Patience Dock) [Glos. Fl.] General
Rumex stenophyllus Ledeb. (Narrow-leaved Dock - GBIF) (Glos. Fl., Stace) [Glos. Fl.] General
Rumex crispus L. ssp. crispus (Stace) (Curled Dock) / General
Rumex crispus L. ssp. littoreus (J. Hardy) Akeroyd. (Curled Dock) / Coasts
Rumex crispus L. ssp. uliginosus (Le Gall) Akeroyd. (Curled Dock) Wetland
Rumex crispus x R. conglomeratus = R. x schulzei Hausskn. (Curled x Clustered Dock) General
Rumex crispus x R. sanguineus = R. x sagorskii Hausskn. (Curled x Wood Dock) /- General
Rumex crispus x R. obtusifolius = R. x pratensis Mert. & W.D.J. Koch (Curled x Broad-leaved Dock) /- General
Rumex crispus x R. obovatus = R. x bontei Danser (Curled x Obovate-leaved Dock) - [Bristol Botany in 1935] General
Rumex conglomeratus Murray (Clustered Dock) / Wetland
Rumex conglomeratus x R. sanguineus = R. x ruhmeri Hausskn. (Clustered x Wood Dock) General
Rumex conglomeratus x R. pulcher = R. x muretii Hausskn. (Clustered x Fiddle Dock) General
Rumex conglomeratus x R. obtusifolius = R. x abortivus Ruhmer (Clustered x Broad-leaved Dock) General
Rumex sanguineus L. (var. viridis Sibth. - Stace) (Wood Dock) / Woodland
Rumex sanguineus L. var. sanguineus (Wood Dock) / General
Rumex sanguineus x R. obtusifolius = R. x dufftii Hausskn. (Wood x Broad-leaved Dock) General
Rumex pulcher L. (ssp. pulcher - NBN, Stace) (Fiddle Dock) /- Grassland
Rumex pulcher L. ssp. woodsii (De Not.) Arcang. (Akeroyd, Kew, GBIF) (ssp. divaricatus (L.) Murb.) (Fiddle Dock) 1942 [Glos. Fl.] General
Rumex pulcher x R. obstusifolius = R. x ogulinensis Borbás (Fiddle x Broad-leaved Dock) General
Rumex obtusifolius L. (var. obtusifolius - Stace, NBN) (Broad-leaved Dock) / General
Rumex obtusifolius L. ssp. subalpinus (Schur) Čelak. (Broad-leaved Dock) was apparently recorded at Avonmouth Docks [B.E.C. 1938, p. 128] - need to check Bristol Museum [Glos. Fl.] - A native of the Balkan peninsula, Turkey and the Caucasus "has leaves glabrous or minutely papillose-scabrid beneath, and valves narrowly triangular, subacute, with several teeth, one valve with a tubercle" (Akeroyd, 2014). "There is no definite evidence of the occurrence of this subspecies in Britain. On specimens...from...Avonmouth Docks...Reichinger wrote as follows: - '...gatherings recall the ssp. subalpinus from S.E. Europe but could be quite as well an unusually small fruited form of ssp. agrestis [var. obtusifolius]'. The material was gathered late and was obviously not good enough for a stable determination of a critical plant." (Lousley in B.E.C., 1938, p. 128). General
Rumex dentatus L. (ssp. klotzschianus (Meisn.) Rech. f. and ssp. halacsyi (Reich.) Reich. f. [Sandwith, 1932] - Stace, Kew) (Aegean Dock) 1928 General
Rumex obovatus Danser. (Obovate-leaved Dock) [Sandwith, 1932] General
Rumex palustris Sm. (Marsh Dock) 1941 Wetland
Rumex maritimus L. (Golden Dock) - Wetland

Species to add:

Persicaria capitata (Buch.-Ham. ex D. Don) H. Gross (Pink-headed Persicaria) /
Polygonum boreale (Lange) Small (Northern Knotgrass) General
Fallopia convolvulus (L.) Á. Löve var. subalatum (Lej. & Courtois) D.H. Kent (Black-bindweed) [Brist. Fl. & Glos. Fl.] /
Rumex acetosa L. ssp. hibernicus (Rech. f.) Akeroyd (Irish Sorrel) - [record is almost certainly wrong.]
Rumex acetosa L. ssp. ambiguus (Gren.) Á. Löve (R. rugosus Campd. - Kew, GBIF) (Garden Sorrel) - 1 BSBI Record
Rumex salicifolius Weinm. (ssp. triangulivalvis Danser - Stace) (R. triangulivalvis (Danser) Rech. f. - Kew, GBIF) (Willow-leaved Dock) [Sandwith, 1932] /
Rumex cuneifolius Campd. (Rumex frutescens Thouars - NBN) (Argentine Dock) [Sandwith, 1932] /
Rumex alpinus L. (Monk's-rhubarb)
Rumex aquaticus × R. crispus = R. x conspersus Hartm. (Scottish x Curled Dock) - seems highly unlikely as R. aquaticus only grows in a restricted part of Scotland. Sandwith (1932) gives in brackets a completely different combination of R. domesticus x obtusifolius which is less unlikely but R. domesticus (now R. longifolius) also only grows in the north. If it is that then the correct name would be R. x hybridus. The record is not mentioned in White (1912) and no more can be found of it. Sandwith puts an asterisk next to it, indicating she hasn't actually seen the specimen. A more likely possibility is that a nomenclatural mistake has been made and possibly what was really intended was R. hydrolapathum x R. obtusifolius = R. x weberi. It is easy to slip up and instinctive to think Water Dock must be R. aquaticus? or possibly it was a naming error for the similar sounding R. confertus (Russian Dock) [Sandwith, 1932] /
Rumex patientia L. ssp. patientia (Patience Dock) [Glos. Fl.] /
Rumex stenophyllus Ledeb. (Narrow-leaved Dock - GBIF) (Glos. Fl., Stace) [Glos. Fl.] /
Rumex crispus x R. conglomeratus = R. x schulzei Hausskn. (Curled x Clustered Dock)
Rumex crispus x R. obovatus = R. x bontei Danser (Curled x Obovate-leaved Dock) - [Bristol Botany in 1935] /
Rumex conglomeratus x R. pulcher = R. x muretii Hausskn. (Clustered x Fiddle Dock)
Rumex pulcher x R. obstusifolius = R. x ogulinensis Borbás (Fiddle x Broad-leaved Dock)
Rumex obtusifolius L. ssp. subalpinus (Schur) Čelak. (Broad-leaved Dock) was apparently recorded at Avonmouth Docks [B.E.C. 1938, p. 128] - need to check Bristol Museum [Glos. Fl.] - A native of the Balkan peninsula, Turkey and the Caucasus "has leaves glabrous or minutely papillose-scabrid beneath, and valves narrowly triangular, subacute, with several teeth, one valve with a tubercle" (Akeroyd, 2014). "There is no definite evidence of the occurrence of this subspecies in Britain. On specimens...from...Avonmouth Docks...Reichinger wrote as follows: - '...gatherings recall the ssp. subalpinus from S.E. Europe but could be quite as well an unusually small fruited form of ssp. agrestis [var. obtusifolius]'. The material was gathered late and was obviously not good enough for a stable determination of a critical plant." (Lousley in B.E.C., 1938, p. 128). /
Rumex obovatus Danser. (Obovate-leaved Dock) [Sandwith, 1932] /

Could occur:

Fallopia baldschuanica x Reynoutria japonica = X Reyllopia conollyana (J.P. Bailey) Galasso (Russian-vine x Japanese Knotweed)
Rumex obtusifolius L. var. microcarpus Dierb. (ssp. sylvestris (Wallr.) Čelak. - Kew, GBIF) (Broad-leaved Dock)
Rumex obtusifolius L. var. transiens (Simonk.) Kubát (ssp. transiens (Simonk.) Rech. f. - Kew, GBIF) (Broad-leaved Dock)

Workings out:

Rumex palustris Sm. (R. limosus auct. non Thuill.) var. confertus Schatz. [not to be confused with R. confertus - Russian Dock. "With confluent, agglomerated whorls." It appears to be just a state where the inflorescence whorls aren't separated but instead all merge into one another, creating a continuous mass and rendering the stem invisible. Lots of photos of ordinary R. palustris on the internet seem to show this feature. It is no longer recognised.] (Sandwith, 1932)