PoLyGonuM. CX. POLYGONACEZ. 473 
sports into many pleasing varieties with yellow and white, red and white, xed 
and yellow flowers. June—Sept. 
2. M. picHotéms. Mexican Four-o’clock.—Fls. sessile, erect, axillary, soli- 
tary —2 From Mexico. Stem 2f high, dichotomous, with yellow flowers, 
opening at 4 o’clock like the former. July, Aug. 
3. M. Ltoncirtora. Long-flowered Fowr-o’clock.—Lvs. pubescent ; fis. crowd- 
ed; tube of the cal. very long.—2 Native of Mexico. Stem 2fihigh. Tube of 
the calyx slender, hairy, twice as long as the leaves. Flowers white. Jn.—Sept. 
_ Orver CX. POLYGONACE #.—Bucxkwouears. 
Herts,rarely shrubs, with alternate leaves. : {base of the leaf-stalks ; occasionally 0. 
Stip. of that remarkable kind called ochree, cohering round the stem in the form of a sheath above the 
Fis. mostly perfect, andinracemes. ee 
Cal.—Sepals united at base, imbricate in estivation. 
Sta. definite, inserted on the calyx near the base. 
Ova. free; with a single erect ovule. Styles or stigmas several. 
Fr.—Achenium usually triangular. rf 
Sds.—Embryo generally on one side of farinaceous albumen. 
Genera 29, species 490, widely diffused throughout the world. 
Properties.—The roots of these plants are nauseous and purgative. Rhubard of the shops is the root 
of some unknown species of this order, native of Tartary. But the leaves and stalks of sorrel, the gar- 
den rhubarb, &c., 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. 
Conspectus of the Genera. 
so Stigmas 3, multifid. 3outersepalssmaller. . . . . Rwumez. = 
6. Stamens.¢9,> Stigmas raultifid. 3. ei os a af wt tet ehh okies) orp Rd ORT 1 
mostly 5, united at base. persistent and enclosing the fruit. . . . Z - Polygonum. 3 
Sepals (4. Radical leaves reniform, on long petioles. . STE ETA es at Cpe aee 
1 RHEUM. 
Rha, the river Volga, on whose banks the plants are said to be native. 
Calyx colored, 6-sepaled, persistent; stamens 9; styles 3; stigmas 
multifid, reflexed ; achenia 3-angled, the angles margined.—% Fis. 
fasciculate, in racemose panicles. 
R. Ruavonticum. Garden Rhubarb or Pie-plant.—Lwvs. smooth, cordate- 
ovate, obtuse; petioles channeled above, rounded at the edges.—Native of Asia, 
cultivated in gardens for the sake of the juicy, acid petioles. These are taken 
in a green state, in the spring of the year, and made into tarts and pies, whose 
excellence is well known to every one. Stem stout and fleshy, 3—4f high, 
hollow, with large, sheathing stipules at the joints. Leaves very large, 1—2f 
long, 3 as wide, on petioles of nearly the same length. Panicle terminal, at 
first enclosed in a white, membranous bract which at length bursts, disclosing 
innumerable greenish-white flowers. May. 
a OXY RIA? . BR. Br: 
Gr. ogvs, acid; in allusion to the qualities of its leaves. 
Cal. 4-sepaled, 2 inner sepals largest ; achenium 3-sided, with a broad, 
membranaceous margin ; sta. 2—6 ; styles 2, stigmas large, plumose._— 
YU Lws. mostly radical, petiolate. Stem nearly leafless, paniculate-racemose. 
O. rENIFoRMIs. Hook. (Rumex digynus. Linn.) Mountain Sorrel. 
_ Radical ls. reniform, on long petioles ; outer sepals oblong, half as long as 
the inner, valvular sepals; stamens 2; styles 2—Found on the summits of the 
White Mts., in moist ravines, and N. to the Arc. Sea. The plant is acid to the 
taste, like Rumex acetosus. Stem 3—4/ in height. June. 
3. POLYGONUM. 
Gr. moXvs, many, yovv, knee ; that is, plants with many joints. 
Sepals 4—6, mostly 5, connected at base, colored or corolla-like, 
persistent ; sta. 5—9, mostly 8; sty. 2—3, mostly 3, short, filiform ; 
ach. mostly triangular, usually covered by the persistent calyx.— 
fTerbaceous. Sts. jownted. Fils. in axillary and terminal fascicles and 
spikes or paniculate racemes. 
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