Polygonaceae . . . . Knotweed family


Choose the best approximation from 3 groups:     Docks,     Knotweeds,    or    Peppers


Docks and similar:

Oxyria
Dock
Rhubarb
Sorrels
Also consider the following similar-looking plants:
Amaranthaceae

Knotweeds and similar:

Polygonum
Fallopia
Fallopia
Fagopyrum

Reynoutria
Muehlenbeckia

Persicaria, peppers and bistorts:

Koenigia polystachya
Koenigia campanulata
Persicaria capitata
Persicaria hydropiper
Himalayan knotweed
Lesser knotweed
Pink-headed persicary
Water pepper

Persicaria maculosa
Bistorta vivipara
Persicaria amphibia
Bistorta officinalis
Redshank
Alpine bistort
Amphibious bistort
Bistort

Persicaria lapathifolia
Pale persicary

Bistorta (was Persicaria) . . . . . Bistorts


Bistorta officinalis (was P. bistorta) . . . . Bistort

Throughout BI

Bistorta vivipara (was P. vivipara) . . . . Alpine bistort

Restricted to mountains, esp. in N En and Sc

A couple of other garden escapes can occur: Rockery bistort (B. affinis) and Red bistort (B. amplexicaule)

Fagopyrum . . . . . Buckwheat


Fagopyrum esculentum . . . . . Buckwheat

Largely a relic of farmland cultivation

Fallopia . . . . . Knotweeds


Fallopia baldschuanica . . . . . Russian vine


Fallopia convolvulus . . . . . Black bindweed

A common weed of waste and arable land

Similar is Copse bindweed (Fallopia dumetorum), to 2 m, rare in S En

Fallopia japonica . . . . . Japanese knotweed

See Reynoutria

Koenigia . . . . . Knotweeds

Several spp. recently transferred here from Persicaria

Koenigia campanulata (was Persicaria campanulata . . . . Lesser knotweed

Naturalised garden escape in various parts of BI; petals divided c.1/2 way to base

Koenigia polystachya (was Persicaria wallichii) . . . . Himalayan knotweed

Scattered throughout BI; to 1.5 m; petals divided nearly to base

Several other spp. occur as garden escapes, including Chinese knotweed (K. weyrichii

Koenigia islandica . . . . Iceland-purslane

A rare tiny annual of Skye and Mull


Muehlenbeckia . . . . . Wire plant


Muehlenbeckia complexa . . . . . Wire plant

Uncommon garden escape

Oxyria . . . . . Mountain sorrel


Oxyria digyna . . . . . Mountain sorrel

Local on mountains

Persicaria . . . . Knotweeds, peppers, bistorts


Persicaria amphibia . . . . Amphibious bistort

Throughout BI

Persicaria bistorta . . . . Bistort

See Bistorta officinalis

Persicaria campanulata . . . . Lesser knotweed

See Koenigia

Persicaria capitata . . . . Pink-headed persicaria

Naturalised in S and CI

Persicaria hydropiper . . . . Water pepper

Very sharp peppery taste; wet places over BI

Persicaria lapathifolia . . . . Pale persicaria

Dense heads of greenish flowers; lvs sometimes with dark spot; Throughout BI

Persicaria maculosa . . . . Redshank

Leaves usually with large dark spot; throughout BI

Persicaria vivipara . . . . Alpine bistort

See Bistorta vivipara

Persicaria wallichii . . . . Himalayan knotweed

See Koenigia

Polygonum . . . . . Knotgrasses

Difficult to separate the various spp. recognised: P. aviculare has leaves crowded together, and of markedly different sizes. Two examples shown

Polygonum aviculare . . . Knotgrass


Polygonum depressum . . . . . Equal-leaved Knotgrass


Other spp. include: Polygonum boreale (Northern knotgrass) which is commoner than P. aviculare in N Scotlnd; Polygonum rurivagum (cornfield knotgrass); and Polygonum maritimum (Sea Knotgrass) which is rather rare

Reynoutria (from Fallopia). . . . . Knotweeds


Reynoutria japonica (was Fallopia japonica) . . . . . Japanese knotweed

A very pernicious escape well established in many areas and hard to eradicate; lvs <15 cm long, can grow to 2-3 m

Less common but even larger (to 4-5 m, with lvs >20 cm long, cordate) is Giant knotweed (R. sachalinensis), widespread

Rheum . . . . . Rhubarbs


Rheum x rhabarbarum. . . . Rhubarb

See also:    Monk's rhubarb

Rumex . . . . . Docks


True docks: Rumex (select from fruit appearance) - or scroll through spp. below


Rumex acetosa . . . . . Common sorrel


Rumex acetosella . . . . . Sheep's sorrel

A generally rather small plant - often <10-15 cm tall; much smaller than R. acetosa; leaves vary from narrow arrow-shaped to broad

Rumex alpinus . . . . Monk's rhubarb

Scattered in Sc and N En

See also:   
Rhubarb

Rumex conglomeratus . . . . . Clustered dock

Damp places; all 3 of 3 tubercles developed (c.f. R. sanguineus)

Rumex crispus . . . . . Curled dock

Leaves with characteristic wavy/crinkled edges

Rumex hydrolapathum . . . . . Water dock

A large plant to >2m; Scattered by ponds and streams

Rumex longifolius . . . . . Northern dock

Damp ground often by water - Sc and N En

Rumex obtusifolius . . . . . Broad-leaved dock

Abundant

Rumex pulcher . . . . . Fiddle dock

Usually with violin-shaped leaves

Rumex rupestris. . . .Shore dock

Very local by the sea between CI and Anglesea

Rumex sanguineus . . . . . Wood dock

Mostly in woods or hedgerows; only 1 of 3 tubercles developed (c.f. R. conglomeratus)

Several other, mostly rare or local, spp. and hybrids can occur