126 
POLYGONUM 
Laminae usually more obtuse at the apex than in any of the other varieties, often larger 
towards the apices of the branches, and rather more succulent. Achenes a little exserted. 
On sand-dunes, northwards to Arran and Fifeshire; Ireland — counties Dublin and Waterford. 
Europe (excl. Arctic) ; northern Africa ; Asia ; North America. 
Waste places, roadsides, field-borders, cultivated land, sand-dunes, and river-gravels liable to 
floods ; common throughout the British Isles. 
Almost the whole world (excl. the Arctic and Antarctic regions), ascending to 2745 m. in the 
Alps (as var. nanum) ; perhaps not indigenous in the southern hemisphere. 
P. aequale x aviculare (p. 127). 
17. POLYGONUM RURIVAGUM. Plate 135 
Polygonum rurivagum [Jordan ex] Boreau FI. Centr. France ii, 560 (1857), inch P. microspermum 
partim ; Norman in Trans. Tyneside Nat. Field Club v, 141 (1863), .including P. microspermum p. 142 parti m ; 
P. aviculare var. longifolium Desvaux Observ. PI. Angers 98 (1818); P. aviadare f. rurivagum Syme Eng. Bot. 
viii, 67 (1868); P. aviadare race rurivagum Rouy FI. France xii, 114 (1912) inch race microspermum p. 113; P. 
heterophyllum subsp. rurivagum Lindman op. cit., p. 691, t. 23, fig. 8, t. 25, fig. 4 (1912)!. 
leones: — Syme Eng. Bot. viii, t. 1231, as P. aviadare f. rurivagum. 
Camb. Brit. FI. ii. Plate 133. (a) Fruiting branches. ( b ) Persistent perianths enclosing achenes (enlarged), 
(e) Achenes (one enlarged). Cambridgeshire (C. E. M.). 
Exsiccata : — Billot, 3769 (a small form), as P. microspermum. 
Root very slender. Stem erect when young, decumbent at maturity, more or less branched ; 
branches often very divaricate, up to 6 dm. long but often much shorter ; internodes usually 
elongate. Ochreae brownish red below, silvery and lacerate above at maturity, longer than in 
the other species of the series Avictilaria. Petiole distinct. Laminae heterophyllous, as in P. 
aviadare , very narrowly elliptical or even linear-acute, about 1*5 — 3^5 cm. long and a third 
or a quarter as broad, narrower than in P. aviculare var. angustissimum, veins conspicuous 
below. Pedicels very short. Flowers often solitary, July to September. Perianth smaller than 
in P. aviadare, pink or white, usually strongly veined in fruit. Achenes smaller than in P. 
aviculare, up to about 2 ’5 mm. long, narrow, a little exserted, sides concave, scarcely shining. 
Small forms of this, of P. aviculare , and of P. aequale are often named P. microspermum. 
Local ; cornfields and waste places ; from Cornwall and Kent to Norfolk, Leicestershire, 
Cheshire, Durham, Dumbartonshire and Perthshire ; chiefly in south-eastern, eastern and central 
England ; perhaps commonest on chalky soils ; not recorded for Ireland. 
Europe. 
18. POLYGONUM AEQUALE. Plate 136 
Polygonum folio rotundo Dillenius in Ray Syn. ed. 3, 146 (1724). 
Polygonum aequale Lindman in Svensk Bot. Tids. vi, 692, t. 23, figs. 10 — 13, fig. 26, figs. 1 — 3 et 
5 (1912)!; P. aviculare L. loc. cit., et auct. pi., partim; P. aviculare var. rotundifolium Gray Nat. Arr. ii, 271 
(1821); P. arenastrum Boreau FI. Centr. France ii, 559 (1857) partim, non Norman in Trans. Tyneside Nat. Field 
Club v, 143 (1863); P. aviculare f. arenastrum Syme Eng. Bot. viii, 65 (1868); P. aviadare var. arenastrum Rouy 
FI. France xii, 1 1 2 (1910). 
leones: — FI. Dan. t. 3017, as P. aviculare var. angustissimum', Syme Eng. Bot. viii, t. 1230, as P. aviadare 
f. arenastrum ; Beck in Reichenbach Icon. t. 206, as P. aviadare f. procumbens. 
Camb. Brit. FI. ii. Plate 136. (a) Flowering branches, (b) Persistent perianth with mature achene (enlarged). 
(c) Mature achene (enlarged). Huntingdonshire (E. W. H.). 
Exsiccata: — Billot, 2733, as P. arenastrum ; Heldreich, 879a, et 879b, as P. litorale ; Sintensis et Rigo, 
667, as P. aviadare var. litorale ; Todaro, as P. gussonei, et 879, as P. dissitiflorum ; Herb. FI. Ingnc. iv, 547, as 
P. aviadare. 
Annual. Stem erect or ascending at least when young, much branched ; branches often 
more or less crowded, subsimple, 1 — 4dm. long; basal internodes 1 — 3cm. long, upper inter- 
nodes often much shorter. Ochreae often shorter than in P. aviculare, more or less scarious at 
