Obdbe 102.— P0LTGONACBJ3. 603 



form, limb spreading ; stamens 5, scarcely with tte style exserted ; 

 achenium enveloped in the persistent base of the calyx. — 2f Herbs 

 mostly Mexican and Peruvian, everywhere cultivated. 



1 M. Salkpa. L. Erect; Ivs. ovate, acuminate, -Jose obtuse or siibcordate, pe- 

 tiolate, glabrous; fls. 3 to 6 in each terminal fascicle, short-stalked; perianth open 

 in the evening and night. — This is the true Four-o'olook, opening its multitudi- 

 nous brilliant flowers at about that hour P. M., for a long suooession of summer 

 days. Their Variety in color is infinite, -j- Peru, 



2 M. dioh6toma L. Erect, glabrous ; Ivs. ovate, subaouminate, hose dbtmss 

 or narrowed to the petiole ; fls. sessile or nearly so ; lobes of invol. ovate-acute ; 

 perianth strict, with a small scarcely dilated liw3>. — (Jardens, lees frequent. Fls. 

 smaller, yellow, red and white, f Mexico. 



3 M. longifldra L. Weak, diffuse, viscid-pubescent ; Ivs. cordate-acuminate, 

 v/pper sessile, lower long-petioled ; fls. sessile, clustered at apex ; invol. lobes 

 Ihiear; tube of t!te pe/rianth very long, piibescent. — Gardens. Pis. white, f Mexica 



3. OXYB'APHUS, Vahl. (Gr. 6^jid^ov, a shallow cup or saucer ; 

 alluding to the form of the involucre.) Involucre 5-cleft, containing 3 

 to 5 flowers (in one species), persistent and spreading in fruit ; perianth 

 with a very short tube, and a plicate, bell-shaped, deciduous limb ; 

 stamens S ; style simple, stigma capitate ; fruit ovoid, ribbed, 1-seeded. 

 — % Herbs with tuberous roots, opposite Ivs. and small fls. (Caly- 

 menia, AUioni.) 



1 O. nyotagineus Sweet. Nearly smootli, erect, with alternate or forked 

 branches ; Ivs. broadly ovate or oblong, svbcordate, acute ; peduncles solitary, 

 axillary and terminal ; invol. pubescent, 3 to 5-flowered. — 2f Alluvial soils, Wis. 

 to Tenn., rare ; common in Nebraska. (Nuttall.) 



2 O. angustifdlius Sweet. St. terete, puberulent above, with alternate branches ; 

 Ivs. narrowly lanceolate, thick but veiny, entire or serrulate, acute, narrowed to 

 the subsessile base ; ped. several times shorter than the leaves, axiUary and termi- 

 nal ; invoL 3-flowered, half-5-clefl, lobes broad, obtuse ; ovary hispid. — Dry soils 

 S. Car., Ga. to La. St. 2 to 3f high. Lvs. 2 to 3' by 5 to 9", or in some speci- 

 mens (A. linearis Ph.) much narrower. Ped. 2 to 5" long. Cal. purplish. Jn. 



3 O. dlbidiis Sweet. St. angular, and pubescent in lines, simple; lvs. narrow, 

 lance-oblong, acute at each end, petiolale ; ped. solitary, axillary, half as long as the 

 hs. ; invol. 2 to 3-flowered, deeply 5-oleft, segm. ovate, acute, ribs of fruit hispid. 

 — (D Dry soils, S. Car., Ga. (^ettauer.) Sts. 12 to 18' high. Lvs. 2' to 30" long, 

 4 to 6" wide. Ped. 1' long, alternate, each with a whitish involucre 10" broad 

 and 2 to 3 small fls. May. (A. alb. Ph.) 



3. BOERHAA'VIA, L. (Dedicated to Bxrhaave, of Holland, a friend 

 and patron of Linnseus.) Involucre ; bractlets deciduous ; perianth fun- 

 tael or bell-form, colored, 5-lobed, upper half deciduous, lower persist- 

 ent ; stamens 1 to 4 ; fruit 5-ribbed, truncate at apex, 1-seeded. — Lvs. 

 opposite, mostly petioled. 



B. ereota L. Glabrous ; lvs. ovate, wavy, palo beneath ; fls. in a strict, much 

 branched panicle. — -1) Sandy soils, S. Car. to Fla. and La. St. 3 to 4f high, nu- 

 merously dividing above into fililbrm, erect branchlets. Lvs. all below, 2' long, 

 roundish at base, on petioles nearly as long. Fig. minute. Jn. — Sept. 



Order CII. POLYGONACE^. Soerelworts. 



Herbs, rarely shrubs, with alternate leaves and mostly sheathing stipules (ocArecB) 

 surrounding the stem above each tumid joint. Flowers mostly perfect. Perianth 

 or calyx 3 to 6-cleft, mostly colored, imbricated in bud and persistent. Stamens 4 

 to 15, perigynous or free. Ovary 1-celled, free, with a single, erect ovule. Styhs 

 or stigmas 2 »r 3. Fruit a 3-angled acheaium enclosed in the calyx. Seed erect, 



