N. ORD.—POLYGONACEZ&. 144 
GENUS.—POLYGONU M,* LINN. 
SEX. SYST.—OCTANDRIA TRIGYNIA. 
POLYGONUM. 
WATER SMARTWEED. 
SYN.—POLYGONUM ACRE, H.B.K.; P. HYDROPIPEROIDES, PURSH. (NOT 
MICHX.); P. PUNCTATUM, ELL. 
COM. NAMES.—WATER PEPPER, SMARTWEED, BITING KNOTWEED; 
(GER.) KNOTERICH. 
A TINCTURE OF THE WHOLE FRESH PLANT POLYGONUM ACRE, H. B. K. 
Description.—This pungently acrid, perennial herb grows to a height of from 
2 to 5 feet. ootstock creeping, ligneous; voos fibrous. Stem simple, smooth, or 
nearly so, rooting at its decumbent base ; sheaths cylindrical, bristly fringed. Leaves 
larger and longer than those of P. hydropiper, L., taper-pointed, Jnflorescence in 
axillary and terminal, erect, slender, filiform, loosely-flowered, spike-like racemes. 
Stamens 8. Style mostly 3-parted; stigmas capitate. Achenia sharply triangular, 
smooth and shining. Cotyledons acumbent, slender; emérvyo in a groove on the 
outside of the albumen, and curved half-way around it; a/éwmen hard and horny. 
Polygonacess.—This large family of herbs, furnished with watery acid or acrid 
juice, is represented in North America by 15 genera, comprising 165 species, the 
truly western genus, Erigonium, alone having 112 species and 10 varieties. The 
order is characterized as follows: Leaves alternate, entire; st#pudes in the form of 
sheaths ( Ochreg), and placed above the usually swollen joints of the stem. Flowers 
mostly perfect; ca/yx more or less persistent, 3- to 6-parted. Stamens 4 to 12. 
Ovary 1-celled; styles or stigmas 2 or 3. rut dry and grain-like; seed single, 
erect, and orthropous; eméryo curved or straightish, on the outside of the albu- 
men, rarely in its centre; vadicle pointing from the base to the apex. 
The only proven plant of this family, beside the four treated of in this work, 
is the Thibetan Rhubarb (Rheum officinale, Baill.). The rhubarbs used in general 
practice, either in lieu of the above species or individually, are: Chinese or Rus- 
sian Rhubarb (2. palmatum, Linn.); English Rhubarb (2. raponticum, Linn.) ; 
R. Webbianum, Royle, R. emodi, Wallich, from China; 2. spiciforme and R. moor- 
croftiianum, Royle, from the West Indies; 2. deucorrhizum, Pal., from the mountains 
of Dolenkara; R. uxdulatum, Linn., from China and Siberia; R. capsicum, Fisch. 
* Tlodé, poly, many; yovv, gonu, knees; from the jointed stems of many species. 
