384 THE POLYGONUM FAMILY. [ Polygonum. 
III, PO LYG ONUM. POLYGONUM. 
Herbs, varying much in habit, but not so stiffly erect as the Docks, ay 
sometimes prostrate, floating, or twining; the scarious stipules usually 
sheathing the stem, and often fringed at the edge; the leaves alternate. 
Flowers small, pale-green or red, clustered or rarely. solitary in the axils of 
the upper leaves, or in terminal heads, spikes, or panicles. Perianth of 5 
(rarely fewer) segments, either all equal or 2 or 3 outer ones enlarged. 
Stamens 8 or sometimes fewer. Styles 3 or 2, sometimes united at the 
base, the stigmas entire. Nut triangular or flattened, enclosed in or sur- 
rounded by the persistent perianth. 
A large genus, widely spread over every part of the globe. 
Stems much branched, wiry, often prostrate. Flowers axillary. 
Annual. Nuts scarcely above a line jong: opaque, dotted, or 
wrinkled . mers: | 
Perennial. Nuts about 2 lines long, very smooth and shining 2 
Stems twining. Flowers in loose racemes. 
Fruiting perianth triangular, scarcely winged : tte 
Fruiting perianth with 3 white, scarious wings . 4 
Stems usually ascending or erect, or floating. Flowers in 
terminal spikes. 
Rootstock perennial. Spikes solitary or rarely two. 
Leaves oblong-linear. Spike slender and linear 5 . & P. viviparum. 
Leaves ovate or oblong-lanceolate. Spike dense, oblong 
or cylindrical. 
Styles 3. Leaves chiefly radical. Stem-leaves few and 
P. aviculare. 
. P. maritimum, 
P 
Hx 
. Convolvulus. 
. dumetorum, 
small 6, P. Bistorta. 
Styles 2. Stems floating or ascending, with large, ob- 
long, stalked leaves. © 0 «0  « 4 PP. amphibium. 
Annuals, Stems branched with several spikes. 
Spikes dense, seldom above an inch long, 
Pedicels and perianths quite smooth, eae. usually 
fringed . 8. P. Persicaria. 
Pedicels and perianth rough with glands. Stipules 
usually entire . 9. P. lapathifolium. 
Spikes long and slender; " the clusters of flowers, at least 
the lower ones, distinct. 
Perianth covered with raised dots. Taste biting . . 10. P. Hydropiper. 
Perianth without raised dots. Taste not biting - . 11. P. minus, 
The tall Persicaria of our gardens is an east Asiatic Polygonum (P. 
orientale), and several other Asiatic species have been recently introduced 
into our flower-gardens. The Buckwheat of agriculturists, occasionally 
found on the margins of fields where it had been cultivated, is also an 
Asiatic plant, included by some in Polygonum (P. Fagopyrum), by others 
separated into a distinct genus under the name of Fagopyrum. 
1, P.aviculare, Linn. (fig. 867). Knotweed Polygonum, Knotgrass. 
—A much branched, wiry annual, prostrate when in the open ground, 
erect when drawn up amongst corn or grass, often a foot or two long. 
Stipules white and scarious, becoming ragged at the edges. Leaves narrow- 
oblong, small, very rarely attaining an inch in length, Flowers small, 
shortly stalked, in clusters of 2 to 5 in the axils of most of the leaves. 
Styles 3. Eruiting perianths but little more than a line long; the seg- 
ments white on the edge, green in the centre. Nuts triangular, seldom 
exceeding the perianth, not shining, and, when seen through a strong glass, 
minutely granulated or wrinkled. 
In cultivated and waste places, almost all over the globe, from the tropics 
to the Arctic regions. Abundant in Britain. #7, almost the whole season. 
