300 DICOTYLEDONOUS PLANTS. 



globose-depressed, purple when mature. The root is a violent 

 emetic. Biff. Mod. Bot. i. 39. Poke Weed. 



2. RIVINA. Linn. 



Perianth 4-parted, persistent. Stamens 4, 8 and 12. 

 Style 1. Berry 1-seeded. Seed lentiform, scabrous. 



Tetrandria. Monogynia. 



R. lavis Linn. : leaves alternate, on long petioles, ovate, acuminate, 

 smooth ; flowers in simple axillary racemes. 



HAB. Penn. Muhl. Sept. *?. A shrub with the habit of Plnj- 

 tolacca decandra. Leaves alternate, entire. Flowers in axillary 

 racemes. 



ORDER C. POLYGONE^. Lind. 



i ., 



Perianth divided, inferior ; aestivation imbricate. Stamens 



definite, inserted in the bottom of the perianth ; anthers burst- 

 ing longitudinally. Ovzry superior, with a single erect ovule. 

 Styles or stigmas several. Fruit a nut, usually triangular, 

 naked or covered bj the enlarged perianth. Seed with 

 farinaceous albumen, 'arely with scarcely any ; embryo invert- 

 ed, generally on one side ; radicle superior. 



Herbs, rarely shruis. Leaves alternate, sheathing at the 

 base or adhering theie to intrafoliaceous stipules, revolute 

 when young. Flowets occasionally diclinous. 



1. POLYGONUM. Linn. 



Perianth 4 6-parted, petaloid, persistent. Stamens 5 9, 

 often 8. Styles 23. Nut one-seeded, mostly triangular. 



Octandria. Trigynia. 



* Floiccrs axillarif Stamens 8. Stigmas 3. POLYGONUM. 



1. P. aviculare Linn. : stem procumbent, herbaceous ; leaves ellip- 

 tic-lanceolate, rough 01 the margin ; nerves of the stipules distant. 



HAB. Waste places. N. Y. to Car. N. to Subarc. Amer. May 

 Sept. 0. Stem much branched, nearly erect. Leaves vary- 

 ing much in siz* and shape. When growing near the sea the 

 leaves are glajicus and rather fleshy, and then forms P. glaucum 

 of Nuttall. This fact is noticed by Dr. Smith, in his Fl. Brit., 

 and by Dr. Grwille in his Flora Edinensis. Knot Grass. 



2. P. erectum Muhl. stem mostly erect ; leaves broad, oval, petio- 

 late, smooth ; flowers pentandrous. P. aviculare var. laltfolium Mich. 

 Ton. 



HAB. Near cultivated grounds. N. S. N. to Subarc. Amer. 

 Aug. 2J..Stzm 13 feet high. Flowers greenish. Dr. Dar- 



