104 POLYGONACEAE. 



1. ULMTJS [Tourn.] L. Shrubs or trees, with furrowed bark and some- 

 times winged branches. Leaves deciduous: blades toothed. Calyx campanu- 

 late. Ovary sessile or nearly so, smooth, but sometimes pubescent. Samara 

 orbicular to oblong. — Spr. — Elm. 



Samaras notched : buds acute : leaf -blades glabrous and nearly fsmooth above, spar- 

 ingly pubescent beneath : flowering pedicels longer than the calyx. 



1. TJ. americana. 



Samaras rounded : buds rounded : leaf-blades very scabrous- 

 pubescent : flowering pedicels shorter than the calyx. 2. U. ftilra. 



1. U. americana L. Tree becoming 40 m. tall, the twigs typically fine- 

 pubescent: leaf -blades oval to ovate, 5-10 cm. long, sometimes slightly rough 

 above: flower-clusters lax, the pedicels long: calyx shallowly lobed: samara 

 oval or obovate, 10-20 mm. long, the wings long-ciliate, narrowed at the base. 



— Common, on roadsides and along streams.. — White-elm. American-elm. 



2. U. fulva Michx. Tree becoming 25 m. tall, the twigs densely pubescent, 

 the inner bark mucilaginous: leaf -blades ovate, oval, or obovate, 8-19 cm. 

 long, very rough-pubescent on both sides: flower-clusters dense, the pedicels 

 short: samara suborbicular, 14-17 mm. in diameter, finely pubescent, the 

 wings eciliate, broad at the iDase. — Common, in rich woods and along streams. 



— Slippery-elm. Eeb-elm. 



2. CELTIS [Tourn.] L. Unarmed shrubs or trees, the bark often warty. 

 Leaves deciduous: blades entire or toothed, very inequilateral. Calyx rotate, 

 the lobes much longer than the tube. Stigmas 2, entire. Drupe subglobose. — 

 Spr. — Hackberry. Nettle-tree. Sugarberry. 



Twigs glabrous : leaf-blades smooth or nearly so above. 1. C. occidcntalis. 



Twigs pubescent : leaf-blades very rough above. 2. C. crassifolia. 



1. C. occidentalis L. Tree becoming 40 m. tall, the twigs glabrous: leaf- 

 blades ovate or rarely oblong-ovate, 5-15 cm. long, smooth or nearly so above: 

 drupes globose or subglobose, 7-10 mm. in diameter, orange, purple or nearly 

 black. — Eather common, especially on the river hills, and along creeks. 



2, C. crassifolia Lam. Tree similar to C. occidentalis in habit : leaf -blades 

 ovate, firm, 3-12 cm. long, scabrous above: drupes oval to subglobose, 7-10 

 mm. in diameter, red-purple or nearly black. — M. Occasional, in rich soil. — 

 Limestones, quartzite. 



Order POLYGONALES. 



Herbs, shrubs, trees, or vines. Leaves alternate, or sometimes oppo- 

 site or wliorled, mostly entire : stipules present, usually as a sheath. 

 Flowers perfect, monoecious, dioecious, or polygamous, variously disposed. 

 Hypanthium long or short. Calyx of 2-5 sepals, which sometimes develop 

 keels or wings. Corolla wanting. Androecium of 2-9 stamens. Gynoe- 

 cium of 2 or 3 united carpels, the ovary superior. Ovule orthotropous. 

 Fruit an achene. 



Family 1. POLYGONACEAE. Buckwheat Family. 



Plants various in habit. Leaves with manifest, usually sheathing, 

 stipules, and inflorescence not involucrate, or the stipules obsolete and the 

 inflorescence involucrate. 



Stigmas tufted. 1. Rumex. 



Stigmas not tufted. 



