Paul Sterry - British Wild Flowers - A photographic guide to every common species

Birthwort Aristolochia clematis (Aristolochiaceae) HEIGHTto 80cm

Upright, unbranched perennial of scrubby places. FLOWERSYellow, tubular, 20–30mm long, fetid-smelling, the swollen base trapping pollinating insects; in clusters (June–Aug). FRUITSGreen, pear-shaped. LEAVESHeart-shaped, strongly veined. STATUSRare and declining; a relict of cultivation for midwifery.

Hall, Jean

Japanese Knotweed

Japanese Knotweed Fallopia japonica (Polygonaceae) HEIGHTto 2m

Fast-growing, invasive perennial, quick to colonise roadsides and other wayside places; hard to eradicate. FLOWERSWhitish, in loose, pendulous spikes arising from leaf bases (Aug–Oct). FRUITSPapery. LEAVESLarge, triangular, on red, zigzag stems. STATUSAlien, but now a widespread garden escape.

Knotgrass

Knotgrass Polygonum aviculare (Polygonaceae) HEIGHTto 1m (often prostrate)

Much-branched annual of bare soil and open ground. FLOWERSPale pink, in leaf axils (June–Oct). FRUITSNut-like, enclosed by the withering flower. LEAVESOval, leathery, alternate with a silvery basal sheath; main stem leaves larger than those on side branches . STATUSWidespread and common.

Equal-leaved Knotgrass

Equal-leaved Knotgrass Polygonum arenastrum (Polygonaceae) PROSTRATE

Mat-forming annual of bare ground and disturbed soil. Superficially like Knotgrass. FLOWERSPale pink, in leaf axils (June–Oct). FRUITSNut-like, enclosed by the withering flower. LEAVESOval, equal in size on main stem and side branches (cf. Knotgrass). STATUSWidespread and common.

Cleave, Andrew

Ray’s Knotgrass

Ray’s Knotgrass Polygonum oxyspermum (Polygonaceae) PROSTRATE

Mat-forming annual of undisturbed coastal sand and shingle beaches. FLOWERSPinkish white, in leaf axils (Aug–Sep). FRUITSNut-like, protruding beyond the withering flower. LEAVESOval, leathery, alternate, sometimes with slightly inrolled margins. STATUSLocal and commonest in the west.

Buckwheat

Buckwheat Fagopyrum esculentum (Polygonaceae) HEIGHTto 30cm

Hairless, upright annual, usually with reddish stems. Associated with disturbed or waste ground. FLOWERSPinkish, in stalked, branched clusters (July–Sep). FRUITSSmooth, 3-sided nuts. LEAVESBroad, arrow-shaped, the upper ones clasping the stem. STATUSWidespread but occasional, a relict of cultivation.

Common Bistort

Common Bistort

Common Bistort Persicaria bistorta (Polygonaceae) HEIGHTto 60cm

Attractive perennial of damp meadows, forming patches in suitable locations. FLOWERSPink, in dense, 30–40mm terminal spikes (June–Aug). FRUITSNut-like. LEAVESOval or arrow-shaped, the lower ones stalked, the upper ones almost stalkless. STATUSLocally common in the north but rare in the south.

See also Sea Knotgrass

Amphibious Bistort

Amphibious Bistort Persicaria amphibia HEIGHTto 40cm

Perennial of ponds and nearby dry land. Aquatic form has floating stems. FLOWERSPink, in cylindrical spikes (June–Sep). FRUITSNut-like. LEAVESNarrow; aquatic forms hairless, truncate at the base and long-stalked; terrestrial forms downy, rounded at the base and short-stalked. STATUSLocally common.

Alpine Bistort

Alpine Bistort Persicaria vivipara HEIGHTto 30cm

Upright, unbranched perennial of upland and northern grassland. FLOWERSIn terminal spikes; upper ones pale pink, lower ones reddish-brown bulbils (a means of vegetative reproduction) (June–Aug). FRUITSNut-like. LEAVESNarrow, grasslike, the margins inrolled. STATUSLocally common from N Wales northwards.

Water-pepper

Small Water-pepper

Water-pepper Persicaria hydropiper HEIGHTto 70cm

Upright, branched annual, characteristic of damp, bare ground such as winter-wet ruts, and shallow water. FLOWERSPale pink, in long spikes that droop at the tip (July–Sep). FRUITSSmall and nut-like. LEAVESNarrow, oval, with a peppery taste when chewed . STATUSWidespread and common, except in the north. Small Water-pepper P. minor is similar but much smaller (to 30cm), with shorter, narrower leaves (5–8mm across) that are not peppery. Local and scarce on bare pond margins.

Redshank

Redshank

Redshank Persicaria maculosa HEIGHTto 60cm

Upright or sprawling hairless annual with much-branched reddish stems . Found on disturbed ground and arable field margins. FLOWERSPink, in terminal spikes (June–Oct). FRUITSNut-like. LEAVESNarrow, oval, usually showing a dark central mark . STATUSWidespread and common throughout.

Pale Persicaria