ORDER 102. POLYGONACE^E. 603 



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

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

 mostly Mexican and Peruvian, everywhere cultivated. 



1 M. Jalapa L. Erect ; Ivs. ovate, acuminate, base obtuse or subcordate, 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'clock, opening its multitudi- 

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

 days. Then* variety in color is infinite, f Peru. 



2 M. dichotoma L. Erect, glabrous ; Ivs. ovate, subaouminate, base obtuse 

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

 perianth strict, with a smaU scarcely dilated limb. Gardens, less frequent. Fls. 

 smaller, yellow, red and white, f Mexico. 



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

 upper sessile, lower long-petioled ; fls. sessile, clustered at apex ; invol. lobes 

 linear; tube of the perianth very long, pubescent Gardens. Fls. white, f Mexico. 



3. OXYB'APHUS, Vahl. (Gr. 6$v[3d<t>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 3 ; style simple, stigma capitate ; fruit ovoid, ribbed, 1-seeded. 

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

 menia, Allioni.) 



1 O. nyctagineus Sweet. Nearly smooth, erect, with alternate or forked 

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

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

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



2 O. angustifolius 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, axillary and termi- 

 nal; invol. 3-flowered, half-5-cleft, 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. albidus Sweet. St. angular, and pubescent in lines, simple; Irs. narrow, 

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

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

 OD Dry soils, S. Car., Ga. (Mettauer.) 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 JScerhaave, of Holland, a friend 

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

 nel 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. erecta L. Glabrous; Ivs. ovate, wavy, pale beneath; fls. in a strict, much 

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

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

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



ORDER CII. POLYGONACE^E. SORRELWORTS. 



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

 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. Styles 

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



