40 POLYGONE^. 



OBDEB XV. POLYGONExE. 



Herbs, or rarely shrubs, with alternate or whorled leaves of revolute 

 vernation; stipules when present cohering around the stem and forming 

 a sheath. Inflorescence various, but commonly racemose and terminal. 

 Calyx of 49 nearly or quite distinct sepals, often colored and petaloid, 

 persistent. Stamens as many as the sepals, or fewer, perigynous. Styles 

 2 4, distinct or somewhat connate, opposite the angles of the lenticular 

 or triquetrous 1-ovuled ovary. Fruit a compressed or triquetrous 

 achene. Seed erect; embryo straight, in the midst of a farinaceous albu- 

 men, or curved around it. 



Leaves alternate, stipulate: 



Sepals 4 6, equal, appressed to the achene POLYGONUM 1 



the outer smaller RUMEX 2 



Perianth tabular below, ti-lo bed above VIBO 3 



Leaves often verticillate, exstipulate: 

 Involucre tubular or campanulate,with 48 ) 



teeth > achenes triquetrous ERIOGONUM 4 



) lenticular OXYTHECA 5 



with 38 cuspidate teeth CHORIZANTHE 6 



Involucre 2-lobed, 1-flowered PTEROSTEQIA 7 



1. POLYGONUM, Columna. Herbs or undershrubs with alternate 

 entire leaves and sheathing stipules. Flowers small, in axillary fascicles 

 or terminal spikes or racemes. Perianth of 5 or 6 nearly distinct often 

 colored and petaloid sepals. Petals 0. Stamens 4 9, commonly in 2 

 sets or circles. Styles 2 or 3, distinct, or connate below, often very 

 short; stigmas capitate. Fruit a triangular or lenticular achene, usually 

 closely invested by the persistent perianth. 



* Leaves jointed upon a short petiole adnate to the 2-lobed or lacerate 



sheath,' flowers axillary to leaves or bracts; filaments of the 3 



inner stamens broad at base; achenes triquetrous. 



H- Glabrous and su/rutescent; sheaths conspicuous; sepals colored. 



1. P. Paronychia, Ch. & Schl. Stems stoutish, ascending or pros- 

 trate, 1 2 ft. long, leafy above, below clothed with the scarious sheaths, 

 these % in. long, brownish and 5 nerved below, lacerate above: leaves 

 sub-coriaceous, 1 in. long, linear-lanceolate, revolute: fl. densely crowded 

 at the ends of the branches, the spikes more or less leafy-bracted i 

 perianth white or rose-color veined with green or brown, % in. long: 

 achene 2 lines long, smooth and shining. In sandy soil near the sea; 

 flowering almost all the year through. 



2. P. Bolanderi, Brew. Stems slender, tufted and strictly erect, 

 ^2 ft. high: sheaths much shorter than the nodes, herbaceous below, 

 scarious and lacerate above, persistent: leaves narrowly linear or sub- 

 ulate, acute or cuspidate, } ^ in. long, not revolute: fl. solitary or few 



