604 Order 102.— POLYGONACB^. 



albuminous, with a straight or curved inverted embiyo. Illust. in Figs. 80, 376^ 

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



Genera 83, species 690 (Meisner) widely diffused in all lands, but most abundant in the tenv 

 porate zones. 



Properties. — The roots of these plants are nauseous and purgative. Rhubarb of the shops ts 

 the root of Rheum palmatum and other species, native of Tartar^. But the leaves and stalkt 

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

 petioles of the latter, together with the farinaceous seeds of the Buck -wheat, are well-known 

 articles of food. 



TRIBES AND GENERA. 



1. ERlOGONEiE. Plowers in dense, involucrato nmbels, OchreEB EniOGONnM. 1 



II. POLVGONE.(E. Flowers not involucrate. Ocbreie present, (a) 



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



a Calyx 6-parted. Stamens 9, Sepals all similar, short Rheum. 8 



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



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



b Sepals, the 8 inner fimbriate-pectinnte. Pedicels solitary Thtsaitella, 5 



b Sepals entire,— -8, closed on the achenia, or all open. Pedicels solitary. Poltoonella. 6 

 — all closed on the achenium. Pedicels usually fascicled.. Polygonum. 7 

 — allopen. Nectaries 8. Pedicels fascicled in tho bract. ..Fagopyrum. 8 



1. ERIOG'ONUffl, Mx. (Gr. tpiov, wool, yow, knee ; being. woolly 

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

 calyx deeply 5-cleft ; stamens 9 ; styles 3 ; achenia 3-angled or S-Iobed ; 

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

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

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

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

 Tol. l-flowered. 



1 E. tomentosum Mi. Lower lvs. crowded, spatulate, obovate or oblong, po- 

 tiolate, beneath rusty white, tomentoua, veina tawny red ; flowering branches 

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

 ered; cat 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. longlfolium Nutt. Lower lvs. crowded, oblong-linear, with a long, attenu- 

 ated base, beneath white-tomentoua, upper lvs. .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^g, 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. — 71 Low, nearly acaulescent, alpine plants. 



O. reniformia Hook. Eadical lvs. reniform, on long petioles ; outer sepala ob- 

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

 summits of the White Mts., in moist ravines ; and N. t6 the Arc. Sea. The plant 

 is acid to the taste, like Rumex acetosus. Stem 3 — t' in height, nearly leafless, 

 racemed or subpaniculato. Jn. (Riimes: digynus L.) 



3. RHE'UM, L. Rhubarb. (iSAa, the river Volga, on whose banks 

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

 stamens 9 ; styles 3, very short, spreading ; stigmas multifid, reflexed ; 

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

 panicles. 



R. Rhaponticum L. Garden Rhubarb or Pie-plant. Lvs. ample, 

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

 Gardena Stem stout and fleshy, 3 — 4f high, hoUow, with large, sheathing sti- 

 pules at the joints. Leaves very large, 1 — 2f long, f as wide, on petioles of 



