004 ORDER 102. POL YG ONAGER. 



albuminous, with a straight or curved inverted embryo. Illust. in Figs. 80, 375, 

 407, 408, 409, 413, 607. 103, 112. 



Genera 33, species 690 (Meisner) widely diffused in all lands, but most abundant in the teni- 

 perate zones. 



I'roperties. The roots of these plants are nauseous and purgative. Rhubarb of the shops i< 

 the root of Kheum palmatiim and other species, native of Tnrtary. But the leaves and xtalts 

 of Sorrel, tho petioles of Garden Khubarb, etc , are agreeably tart, and contain oxalic acid ; the 

 prtioles of the latter, together with the farinaceous seeds of the Buck-wheat, are well-know u 

 article* of food. 



TRIBES AND GENERA. 



1. ERIOGONE^E. Flowers in dense, involucrato umbels, Ochrese EKIOGONUJI. 1 



II. POLYGONE^E. Flowers not involucrate. Ochreae present, (a) 



a Calyx 4-parted, regular. Stamens 6. Styles 2. Achenia winged OXYKIA. 2 



a Calyx 6-parted. Stamens 9. Sepals all similar, short RIIEUV. 3 



a Calyx 6-parted. Stamens 6. Sepals 8, inner increasing, tuberculate EUMEX. 4 



a Calyx 5-parted (irregularly 4-parted in one species), (b) 



b Sepals, the 3 inner fltnbriate-pcctinate. Pedicels solitary TIIYSANEI.LA. 5 



b Sepals entire, 3, closed on the achenia, or all open. Pedicels solitary .POLYGOXELLA. 6 

 all closed on the achenium. Pedicels usually fascicled. .POLYGONUM. 7 

 all open. Nectaries S. Pedicels fascicled in tho bract... FAGOPYKUM, S 



1. ERIOG'ONUM, MX. (Gr. eptov, wool, yo vv, knee ; being woolly 

 at the joints, etc.) Flowers many in each common 5-toothed involucre ; 

 calyx deeply 5-clcft ; stamens 9 ; styles 3 ; aehenia 3-angled or 3-lobed ; 

 embryo in or near the axis of scanty albumen. Herbs clothed with 

 dense cottony \vool. Lvs. alternate, exstipulate, mostly at the base of 

 the stem, the upper bract-like, often whorled at the forks of the umbel- 

 late inflorescence. Invol. solitary or capitate. Pedicels within the in- 

 vol. 1-flowered. 



1 B. tomentosum MX. Lower Ivs. crowded, spatulate, obovate or oblong, pe- 

 tiolate, beneath rusty white, tomentous, veins tawny red ; flowering branches 

 several times forked ; invol. solitary, campanulate, sessile, 5-toothed, loose-flow- 

 ered; cal. colored, funnel-form. U Sandy hills, S. Car. to Fla.. frequent. St. 1 

 to 3f high. Lvs. 2 to 3' long, those of the stem much smaller. Fls. 3 to 4" long, 

 cream-white, with wool of the same color outside. Jn. Aug. 



2 E. longifolium Nutt. Lower Ivs. crowded, oblong-linear, with a long, attenu- 

 ated base, beneath white- tomentous, upper Ivs. scattered ; panicle ample, several 

 times forked ; bracts minute ; invol. solitary, campanulate, pedunculate many- 

 flowered ; cal. green, woolly. Fla. to Ark. St. 2 to 4f high. 



2. OXYR'IA, R. Br. MOUNTAIN SORREL. (Gr. o^ijg, acid ; in allu- 

 sion to the qualities of its leaves.) Calyx herbaceous, 4-sepaled, the 2 

 inner sepals erect, larger, the 2 outer reflexed ; achenium lens-shaped, 

 thin, girt with a broad, membranous wing; stamens 6, equal ; stigmas 



2, sessile, penicillate. 1 Low, nearly acaulescent, alpine plants. 



O. reniformis Hook. Radical Ivs. reniform. on long petioles ; outer sepals ob- 

 long, half as long as the inner, valvular sepals ; fruit orbicular. Found on the 

 summits of the White Mts., in moist ravines ; and N. to the Arc. Sea. Tho plant 

 is acid to the taste, like Rumex acetosus. Stem 3 4' in height, nearly leafless, 

 racemed or subpaniculate. Jn. (Rumex digynus L.) 



3. RHE r UM, L. RHUBARB. (Rha, the river Volga, on whose banks 

 the plants are said to be native.) Calyx colored, 6-sepaled, persistent ; 

 ::tamens 9 ; styles 3, very short, spreading ; stigmas multifid, reflexed ; 

 uchenia 3-angled, the angles margined. If Fls. fasciculate in racemous 

 panicles. 



R. Rhaponticum L. GARDEN RHUBAKB OR PIE-PLAXT. Lvs. ample, 

 smooth, cordate-ovate, obtuse ; petioles channeled above, rounded at the edges. 

 hardens. Stem stout and fleshy, 3 4f high, hollow, with large, sheathing st;'- 

 ].i:I,'3 at the joints. Leaves very large, 1 1 1" long:. ? as wide, en petioles of 



