Polygonum.'] lxxii. polygonace.e. 
369 
Ord. LXXII. POLYGONACE2E Juss. 
Sometimes monoecious or dioecious. Perianth free, divided, 
the segments often in a double row. Stamens definite, but 
varying in number, inserted into the base of the perianth. Ovary 
superior, with 2 or more styles or sessile stigmas. Achene. fre- 
quently triangular or lenticular, with one erect seed. Embryo 
in a farinaceous albumen, often lateral. — Herbaceous, rarely 
shrubby plants, with sheathing stipules! — The stems and leaves 
are acid and astringent ; the roots, in general, nauseous and 
purgative; while the seeds are very farinaceous and esculent. 
The true rhubarb belongs to this Older: it is a species of 
llheum not clearly ascertained. 
1. Polygonum. Perianth 5-partite. Styles 2 — 3. Achene wingless 
compressed or triqut trous. 
2. Rumex. Perianth G-partite ; the three inner segments at length larger, 
connivent and covering the triquetrous wingless achene. Styles 3. 
3. Oxyria. Perianth 4-partite : the two inner segments larger. Styles 
2. Achene compressed, with a membranous wing, at length 
larger than the perianth. 
1. Polygonum Linn. Persicaria, Bistort, Knot-grass, and 
Buck-wheat. 
Perianth single, in 5 deep, coloured, persistent segments. 
Stain. 5 — 8. Styles 2 — 3. Achene compressed or trigonous. — 
Named from iroKvc, many , and yorv, a knee or joint ; from the 
numerous joints of the stem. 
* Styles 3, and the fruit triquetrous. Stem simple, with one terminal 
spiked raceme. Stipules truncate. Root thick and short. Bistort. 
1. P. Bistdrta L. ( common B., or Snakeweed ) ; raceme dense 
cylindrical, leaves subcordate-ovate waved, the radical ones 
with a winged foot-stalk. E. B. t. 509. 
Moist meadows in various parts of England, Scotland, and Ireland. 
I).. 6 — 9. — Stem 1 — 1| foot high. Upper tea ves with long sheaths. 
Flowers flesh-coloured, on short foot-stalks, with small bracteas at 
their base. Siam. 8. Styles 3. Root large, tortuose, very astrin- 
gent. 
2. P. viviparum L. ( viviparous alpine B.) ; spike linear lax 
bulbiferous at the base, leaves linear-lanceolate the lower ones 
elliptical petiolate their margins revolute, foot-stalks not 
winged. E. B. t. 669. 
Mountain pastures in the north of England, and abundant on the 
Highland mountains of Scotland. y. 6, 7. — Stem 4 — 8 inches 
high, slender. Spike linear; lower part of it generally bearing little 
viviparous bulbs of a fine red colour. Siam. 8. Styles 3. Perianth 
pale flesh-coloured, almost white This species increases much by 
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