386 THE POLYGONUM FAMILY. — [Polygonum. 
In alpine pastures, often at great elevations, in all the great mountain- 
ranges of Europe and Asia, descending to lower levels in the north, and 
penetrating far into the Arctic regions, Frequent in the Highlands of 
Scotland, and occurs also in northern England and North Wales, and on 
Ben Bulben, in Ireland. £7. summer. 
6, P. Bistorta, Linn. (fig. 872). Bistort Polygonum, Bistort, Snake- 
weed, — Perennial rootstock thick, and often spreading considerably. Radi- 
cal leaves in broad patches, on long stalks, ovate-lanceolate or cordate, 
often 3 to 6 inches long, Stems simple and erect, 1 to 2 feet high, with a 
few nearly sessile leaves, and terminating in a single, dense, oblong, or 
cylindrical flower-spike, 1 to 2 incheslong. Perianth pink or rarely white. 
Styles 3. Stamens longer than the perianth. 
In moist pastures, and meadows, chiefly in hilly districts, in Europe, 
central and Russian Asia, and northern America, extending into the Arctic 
regions, Occurs in various parts of Britain, chiefly in the north of England 
and south of Scotland, but is local, and in some instances a straggler from 
gardens. Fl. summer. 
7. P. amphibium, Linn. (fig. 873). Amphibious Polygonum.—A 
glabrous perennial, usually floating in water, and rooting at the lower 
nodes. Leaves oblong or lanceolate, rather thick, 3 to 6 inches long, 
spreading on the surface of the water. Spikes terminal, solitary or rarely 
two together, supported on short peduncles above the water, dense and 
cylindrical, 1 to 14 inches long, of a rose-red. Stamens usually 5. Styles 2. 
Nuts flattened. 
In ponds and watery ditches, in Europe, cetral and Russian Asia, and 
northern America, to the Arctic regions. Extends all over Britain. FF, 
summer. When growing in dried-up ponds or muddy ditches the stems 
are creeping at the base, then shortly erect, and the leaves are often 
downy. 7 
8. P. Persicaria, Linn. (fig. 874). Persicaria Polygonum, Common 
Persicaria.—An erect or spreading, branched annual, glabrous or slightly 
hoary, and often turning red, 1 to 2 feet high. Leaves lanceolate, stalked, 
or the upper ones sessile ; the larger ones 3 to 5 inches long, and an inch 
broad or rather more, often marked in the centre with a dark spot. 
Stipules more or less fringed at the top with short fine bristles. Spikes 
terminal, rather numerous, oblong or cylindrical, and seldom above an inch 
long, dense, but not so regular as in P. amphibium, and there is often a 
cluster of flowers a little below. Flowers reddish or sometimes green, not 
dotted. Stamens usually 6. Styles usually 2. Nuts flattened but rather 
thick, smooth and shining, and often concave on one side. Occasionally 
there are 3 styles, and the nut is then triangular. : 
In ditches, on roadsides, in cultivated and waste places, throughout 
Europe and central and Russian Asia to the Arctic regions, Abundant in 
Britain, Fl. all summer and autumn, It varies much in stature and in 
colour, in the number and density of the spikes, and in the achenes more 
or less concave or convex on one or both sides. | 
9. P. lapathifolium, Linn. (fig. 875). Pale Polygonum.—Closely 
resembles P. Persicaria, and is probably a mere variety, distinguished by 
the pedicels and perianths dotted with small prominent glands, ‘The 
colour of the plant is usually pale green, the stipules seldom fringed, 
