108 BOTANY. 
erect ; albumen farinaceous; embryo anatropal, generally on one side, some- 
times in the axis of the albumen; radicle superior. Herbaceous, rarely 
shrubby plants, with alternate, stipulate, or exstipulate leaves, and. often 
unisexual flowers. They are found in almost all parts of the world, more 
especially in the temperate regions of the northern hemisphere. They grow 
in fields, waste grounds, ditches, mountains, &c. The order has been 
divided into two tribes: 1. Polygonez, with loose flowers, embryo usually 
abaxial, ochreate stipules. 2. Hriogonez, with involucrate flowers, embryo 
axial, leaves generally exstipulate. Lindley enumerates twenty-nine genera, 
including 490 species. Examples: Polygonum, Rumex, Rheum, Erio-_ 
gonum. 
The species of the typical genus Polygonum are inconspicuous in ap-_ 
pearance, and generally stigmatized as worthless weeds. A common species 
growing in damp yards and other localities, is called smart-weed (P. hydro- 
piper) from its intense acridity. It is said to drive away the small red ant 
when laid in places infested by this animal. Some species, as P. sagittatum, 
form almost impenetrable growths in meadows, on account of the sharp- 
toothed prickles along the angular stem and leaves. The common Buck- 
wheat, Fagopyrum esculentum, is, in all probability, a native of North- 
western China, and was not known in Hurope before the sixteenth century. 
Species of Rumex form the sheep sorrel of old fields. The most important 
genus is Rheum or Rhubarb, the root rhubarb being furnished by many 
species indigenous to Siberia, Thibet, Northern China, and the Himalaya 
Mountains. Rheum compactum and rhaponticum have acid petioles, in much 
request for making pies. 
Rheum palmatum, Rhubarb (pl. 60, 61, fig. 4); a, the root; b, the stem ; 
c-f, flowers and fruit in different states. 
Orpver 75. Puyrotaccacem, the Pokeweed Family. Perianth four- to 
five-partite. Stamens usually perigynous, indefinite, or equal to the segments 
of the perianth, and alternate with them. Ovary of one or several carpels, 
distinct or combined; ovule one in each carpel, ascending or erect; styles 
equal to the carpels in number, terminal or lateral; stigmas simple or divided. 
Fruit fieshy and dry, indehiscent, sometimes samaroid. Seeds solitary, erect 
or ascending; embryo straight or curved; albumen mealy or 0; radicle next 
the hilum. Undershrubs or herbs, with alternate, entire leaves, which are 
often dotted. They are natives both of tropical and warm countries, and are 
found in America, Asia, and Africa. 
Sub-order 1. Petiveriacee. Cotyledons convolute. Leaves stipuled. Tro- 
pical America. 
Tribe 1. Petiveriez. Embryo straight or slightly curved, perisperm none 
or much reduced. Examples: Sequieria, Petiveria. 
Tribe 2. Rivinee. Embryo annular, inclosing a mealy perisperm. Exam- 
ples: Mohlana, Rivina. , 
Sub-order 2. Phytollaccinee. Seeds ascending, cotyledons plane, leaves 
exstipulate. 
Tribe 3. Limea. Testa of membranous grains. South African plants. 
Examples: Limeum, Gaudinia, &c. 
108 
