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 floAvers. 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. Polygonea?, Avith loose iiowers, embryo usually 

 abaxial, ochrcate stipules. 2. Eriogonere, with involucrate flowers, embryo 

 axial, leaves generally exstipulate. Lindley enumerates twenty-nine genera, 

 including 400 species. Examples : Polygonum, Rumex, Rheum, Erio- 

 gonum. 



The species of the tj^pical genus Polygonum are inconspicuous in ap- 

 pearance, and generally stigmatized as Avorthless Aveeds. A common species 

 growing in damp yards and other localities, is called smart-Aveed (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 groAvtlis in meadows, on account of the sharp- 

 toothed prickles along the angular stem and leaves. The common Buck- 

 Avheat, Fagopyrum esculentum, is, in all probability, a native of North- 

 Avestern China, and Avas not knoAvn in Europe Ijefore 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 

 recjuest for making pies. 



Rheum palmatum. Rhubarb { jil. 60, 61. fi»". 4) ; o, the root ; 6, the stem ; 

 c-f. flowers and fruit in different states. 



Order 75. Phytolaccacea:, the PokcAveed Family. Perianth four- to 

 fiA'e-partite. Stamens usualh' perigynous, indefinite, or equal to the segments 

 of the perianth, and alternate Avith 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 jlivided. 

 Fruit fleshy and dry, indehiscent, sometimes samaroid. Seeds solitary, erect 

 or ascending ; embryo sti-aight or curved ; albumen mealy or ; radicle next 

 the hilum. Undershrubs or herbs, Avith tilternate, entire leaves, Avhich are 

 often dotted. They are natives both of tropical and Avarm countries, and are 

 found in America, Asia, and Africa. 



S'nb-order 1. Pefioerlacecc. Cotyledons convolute. LeaA'es stipuled. Tro- 

 pical America. 



Tribe 1. PetiveriecB. Embryo straight or slightly curved, perisperm none 

 or much reduced. Examples : Sequieria, Petiveria. 



Tribe 2. Ririiiece. Embryo annular, inclosing a mealy perisperm. Exam- 

 ples : Mohlana, Rivina. 



Sub-order 2. Phytollaccinece. Seeds ascending, cotyledons plane, leaves 

 exstipulate. 



Tribe 3. Llmea. Testa of membranous grains. South African plants. 

 Examples : Limeum, Gaudinia, (fcc. 

 108 ■ 



