POLYGONUM 
1 15 
7. POLYGONUM AMPHIBIUM. Amphibious Bistort. Plate 122 
Potamogiton angustifolium Gerard Herb. 675 (1597); Persicaria salicis folio perennis potamogiton angusti- 
folium dicta Ray Syn. ed. 3, 145 ( 1 724). 
Polygonum amphibium L. Sp. PI. 361 (1753)!; Syme Eng. Bot. viii, 77 (1868); Rouy FI. France 
xii, 96 (1910). 
leones: — Curtis, FI. Lond. ii, t. 81 ; Smith Eng. Bot. t. 436; FI. Dan. t. 182; Beck in Reichenbach Icon. 
xxiv. 
Camb. Brit. FI. ii. Plate 122. (a) Flowering shoot of P. amphibium. (b) Young shoot of P. amphibium 
f. terrestre. ( c ) Flowers (enlarged), one with perianth dissected. ( d ) Pistil (enlarged). Huntingdon (E. W. H.). 
Exsiccata : — Billot, 1061, as P. amphibium var. natans ; 1061 bis; Todaro, 1074; Herb. FI. Ingric. vi, 
538 b, as P. amphibium var. caenosum. 
Perennial. Rhizome long, slender, branched. Aerial stem erect, not or little branched. 
Ochreae large (8 — 10 cm. long), appressed to the stem, entire at first, ultimately more or less 
laciniate. Laminae usually floating on the water, subcordate at the base, large, up to 10 — 12 cm. 
long and 3 broad. Peduncle stout, longer than the spike, up to 5 or 6 cm. long, eglandular. Spike 
solitary or subsolitary, about 4 cm. long. Bracts ovate. Flowers crowded ; July to September. 
Perianth subsessile, deeply cleft ; segments about 4 mm. long, not obviously nerved, rosy red. 
Stamens 5, as long as the perianth. Style as long as the stigmas. Stigmas 2, large, stout. Achenes 
broadly obovate, much shorter than the persistent perianth, about 3 mm. long and 2 broad. 
(J 3 ) forma terrestre nobis; P. amphibium var. terrestre Leysser FI. Hal. 391 (1761); Leers FI. Herborn. ed. 
2, 99 (1799); Stokes Bot. Mat. Med. ii, 391 (1812); Rouy FI. France xii, 96 (1910). 
leones Syme Eng. Bot. t. 1241, as “ P. amphibium , terrestre'.' 
Exsiccata: — Herb. FI. Ingric. ix, 538 b, as P. amphibium var. terrestre. 
A state of damp or dry soils. Stem more or less hairy, about 3 — 10 dm. high. Ochreae 
ciliate. Petioles shorter than in the water-form. Laminae larger and more hairy. 
Ponds, ditches, and marshes ; waste places, arable land, and road-sides ; locally abundant 
throughout the British Isles, chiefly in lowland districts. 
Faeroes, Scandinavia, Denmark, Germany, France, central Europe, Russia, southern Europe ; 
Asia; North America; South Africa. 
Series ii. Persicariae 
Persicariae nobis. 
For characters, see page 114. Only British species: — P. persicaria. 
8. POLYGONUM PERSICARIA. Common Persicaria. Plate 123 
Persicaria maculosa Gerard Herb. 361 (1597); Ray Syn. ed. 3, 145 (1724). 
Polygonum persicaria L. Sp. PI. 361 (1753)!; Smith FI. Brit. 424 (1800); Engl. FI. ii, 233 (1824); 
Syme Eng. Bot. viii, 74 (1868); Rouy FI. France xii, 97 (1910); P. ruderale Salisbury Prodr. 259 (1796); 
Persicaria mactilosa Gray Nat. Arr. ii, 269 (1821); P. biforme Wahlenberg FI. Suec. i, 242 (1826). 
Camb. Brit. FI. ii. Plate 123. (a) Flowering shoot, (b) Part of stem, with leaf, of P. persicaria var. 
elatum. {c) Lower part of stem of var. elatum. ( d ) Ochrea (enlarged) of var. elatum. (e) Achenes (enlarged). 
(/) Persistent perianths (enlarged), enclosing nutlets, (g) Peduncle (enlarged). Huntingdonshire (E. W. H.). 
Annual. Stem erect and up to about 2 — 5 dm. high or decumbent, branched ; branches more 
or less divaricate and remote ; nodes more or less swollen. Ochreae loose, short, ciliate with long 
hairs. Petioles short. Laminae ovate-lanceolate, frequently with a dark blotch, more or less pubescent 
underneath, eglandular, upper ones subsessile. Peduncles short, punctate, eglandular. Spike cylindrical, 
erect or suberect, lateral ones subsessile. Perianth eglandular or only minutely glandular, pink, 
rarely white; early July to October. Stamens 5 — 8, shorter than the perianth. Anthers small, 
oval, those of the outer stamens extrorse. Style as long as the stigmas. Stigmas 2 — 3, ultimately 
divaricate, globose, stout. Achenes bifacial or trigonous, suborbicular-acute, about 2^5 mm. long and 
2 'o broad, equal in length to the persistent perianth, nearly black. 
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