652 PETIVERIACEXZ.—POLYGONACEA. 
Order 6. PETIVERIACE#, the Petiveria Order.— Diagnosis, &e. 
This is a small order of plants, which is included by some 
botanists, as Bentham and Hooker, in Phytolaccacez, with 
which it agrees in many particulars. It is distinguished from 
that order by having stipulate leaves, an ovary formed of a 
single carpel, exalbuminous seeds, and a straight embryo with 
convolute cotyledons. These plants are natives of tropical 
America. There are about 12 species in this order. 
Properties and Uses.—Most of the species are acrid, and 
some have a strong alliaceous odour. 
Petiveria—Petiveria alliacea, Guinea-hen Weed, is reputed to be sudorific 
and emmenagogue, and its roots are used in the West Indies as a remedy 
for toothache. It is also commonly put into warm baths which are used to 
restore the action of paralysed limbs. 
Order 7. Potyeonace&#, the Buckwheat Order.—Cha- 
racter.—Herbs or rarely shrubs. Leaves alternate, simple, com- 
monly with ochreate stipules above the swollen joints (nodes) of 
Pie: 103. 
Fiest032: 
Fig. 1031. Flower of 
a species of Polygo- 
num.——Fig. 1032. 
Pistil of a species 
of Rumex. 
the stem (fig. 21, d), or rarely exstipulate. Flowers perfect 
(fig. 1031), or sometimes unisexual. Calyx inferior (jig. 1021), 
of from 3—6 sepals, more or less persistent, imbricate. Stamens 
few (fig. 1031), hypogynous or rarely perigynous ; anthers de- 
hiscing longitudinally. Ovary superior (fig. 1031), 1-celled ; 
styles and stigmas 2—3 (fig. 1031); ovule solitary, orthotropous. 
Fruit usually a triangular nut, and commonly enveloped in the 
persistent calyx. Seed solitary, erect (fig. 780) ; generally with 
farinaceous albumen ; embryo (fig. 780, pl) antitropous. 
Diagnosis.—Usually herbs with ochreate stipules. Leaves 
simple, alternate. Calyx inferior, persistent, imbricate. Stamens 
definite. Ovary 1-celled; styles and stigmas 2—3. Fruit 
triangular. Seed solitary, erect, usually with mealy albumen, 
radicle superior. 
Distribution and Numbers.—Generally diffused over the 
globe, and more particularly so in temperate regions. llus- 
trative Genera:—Rheum, Linn. ; Polygonum, Linn. ; Coccoloba, 
Jacq. ; Rumex, Linn. There are about 500 species. 
Properties and Uses.—Chiefly remarkable for the presence of 
acid, astringent, or purgative properties. The acidulous cha- 
