1 18 
POLYGONUM 
A smaller plant, usually of drier soils. Laminae smaller, relatively narrower, whitish underneath. 
This is a very variable species ; but we are unable to classify the British forms and varieties. In fact, we suspect that 
most of the British plants named P. nodosum or P. maculatum are hybrids formed by the crossing of P. persicaria and P. 
lapathifoliu m. 
Sides of ponds, ditches, and rivers, and also in rich arable and waste land in the lowlands. 
Local but widespread in southern, central, and eastern England ; rare in Wales and northern 
England ; recorded for southern Scotland (northwards to Perthshire) ; rare in hilly districts generally ; 
rare (or not distinguished) in Ireland — counties Kerry, Cork, Wexford, Carlow, Westmeath, and Down. 
Scandinavia, Denmark, Germany, France, central Europe, Russia, southern Europe; northern 
Africa ; Asia ; America ; South Africa. 
P. hydropiper X nodosum Grenier et Godron FI. France iii, 49 (1855); Rouy FI. France xii, 104 
(1910); P. laxum Reichenbach Iconogr. Crit. v, 56 (1827); x P. laxum Reichenbach FI. Germ. Excurs. 572 
(1830); P. hydropiper x tomentosum Beckhaus FI. Westf. 774 (1893); P. hydropiper x lapathifolium Giirke PI. 
Etirop. ii, 120 (1897). 
leones : — Reichenbach Iconogr. Crit. t. 492, fig. 685, as P. laxum. 
Stem erect or decumbent, with the terminal branches usually suberect. Ochreae lax, long, 
shortly ciliate. Petioles short. Laminae broadly lanceolate, wavy, attenuate at each end. Peduncles 
not or scarcely glandular. Spikes attenuate before flowering, ultimately subcylindrical, dense-flowered, 
not or scarcely interrupted. Perianths pink, not or scarcely glandular ; August and September. 
Stamens 5. Style as long as the stigmas. Stigmas 2, ultimately spreading. Achenes bifacial, 
suborbicular-acute. 
Cambridgeshire, Huntingdonshire. 
Scandinavia, Germany. 
Series iv. Hydropiperes 
Hydropiperes nobis. 
For characters, see page 114. Only British species: — P. hydropiper. 
II. POLYGONUM HYDROPIPER. Water Pepper. Plate 126 
Persicaria hydropiper Gerard Herb. 361 (1597); P. vulgaris acris seu hydropiper Ray Syn. ed. 3, 144 (1724). 
Polygonum hydropiper L. Sp. PI. 361 (1753); Smith Ft. Brit. 426 (1800)!; Syme Eng. Bot. 70 
(1868); Rouy Ft. France xii, 100 (1910). 
leones: — Curtis Ft. Loud, i, 75; Smith Eng. Bot., t. 989; Ft. Dan. t. 1576; Reichenbach Iconogr. Crit. 
t. 494, fig. 687; Beck in Reichenbach Icon. t. 21 1. 
Camb. Brit. Ft. ii. Plate 126. ( a ) Flowering branches, (b) Lower part of stem. ( c ) Leaves from 
lower part of stem, (d) Lower part of stem, with ochrea (enlarged). ( e ) Persistent perianths (enlarged), enclosing 
achenes. (/) Achenes (enlarged). Huntingdonshire (E. W. H.). 
Exsiccata : — Billot, 72 ; Herb. Ft. Ingric., iv, 544. 
Annual, very acrid to the taste. Stem erect or decumbent, 2 — 8 dm., branched, sometimes 
rooting at the base. Ochreae large, somewhat inflated, glabrous or nearly so, upper margin slightly 
ciliate. Petioles very short. Laminae lanceolate-acuminate, attenuate at each end, margin more or 
less wavy, about 5 — 10 cm. long, broadest below the middle, upper ones sessile. Spikes rather 
slender and interrupted, drooping. Flowers July to October. Perianth glandular, without conspicuous 
nerves, greenish or pinkish ; segments 5, about as long as the tube. Stamens 5 — 8, usually 6, 
shorter than the perianth. Style very short. Stigmas 2 — 3, globose, projecting beyond the stamens. 
Achenes large (about 2^5 — 3’o cm. long), ovate-acute, punctate, dull, flat on one side, convex on 
the other, as long as the persistent perianth. 
According to Praeger, R. hydropiper is “strongly calcifuge ” in Ireland (see Irish Top. Bot., p. 271); but this does not 
apply to its occurrence in England. 
Shallow ditches, and damp and watery places in general ; common throughout the whole of 
England, Wales, southern and eastern Scotland and Ireland; local in western and northern Scotland; 
ascending to nearly 400 m. in the Lake District. 
Europe; northern Africa; Asia; North America. 
