ORDER LXVIH. COMPOSITE. 385 



Genus XLL— MELAX'THERA. Rohr. 

 (From melas, black, and anthera, the anther.) 



Involcure many-leaved. Leaves in a double series, equal, 

 oblong-lanceolate. Florets all perfect. Seeds quadrangular, 

 compressed. Pappus consisting of a few bristles. Receptacle 

 chaffy, convex. 



1. 11 hasta'ta, (Mich.) Stein erect, quadrangular, furrowed, sca- 

 brous, branching. Leaves hastate, 3-lobed, decussate, lanceolate, den- 

 tate, scabrous, and somewhat hispid, petiolate. Flowers solitary, on 

 peduncles, usually in pairs ; involucre hispid. Corolla tubular, 5-cleft. 

 Seed slightly winged at the angles ; chaff leaf-like. — "White. If . Aug. 

 — Sept. Rich soils. 4 — 6 feet. 



2. M. deltoid'ea, (Mich.) Stem quadrangular. Leaves opposite, ovate- 

 deltoid, evanescent. Scales of the involucre ovate. — Elorida. 



Gexus XLIL— ZIX'XIA. L. 



(In honor of Godfrey Zinn, a German.) 



Heads many-flowered ; ray florets pistillate, those of the disk 

 perfect. Receptacle conical, chaffy. Rays obovate, coriaceous, 

 lobes of the disk villous. Ackenia of the ray 3-sided, mostly 

 destitute of pappus. Herbaceous plants, with opposite, entire, 

 and sessile leaves. Heads solitary. 



1. Z. multiflo'ka, (L.) Stem erect, hirsute. Leaves ovate-lanceolate, 

 peduncles larger than the leaves, with the apex hollow and inflated. — 

 Yellow or purple. Car. and Ala. 



Gexus XLIIL— HELIOP'SIS. Pers. 

 (From htlios, the sun, and opsis, appearance ; from its resemblance to the sun-flower.) 



Involucre imbricate, many-leaved ; ray florets pistillate, those 

 of the disk perfect. Receptacle conic. Seed quadrangular 

 Pappus wanting. 



1. H. L-e'vis, (Pers.) Stem erect, glabrous, dichotomously branched. 

 Leaves opposite, ovate-lanceolate, serrate, 3-nerved, glabrous. Flowers 

 terminal, and in the angles of the stem, on long peduncles. Leaves of 

 the involucre oblong. Seed naked ; receptacle convex. — Yellow. 2T. 

 May — June. Sandy soils. 2 — 4 feet. 



Gexus XLIV.— TETRAGOXOTHE'CA. Dill. 

 (From tetra, four, gonia, angle, and ihtka, a capsule.) 



Involucre gamosepalous, deeply 4-parted, 4-angled, with 

 broad hairy segments. Receptacle chaffy. Seed obovate, pu- 

 bescent at the summit. Pappus wanting. 



1. T. heliaxthoi'des, (L.) Stem erect, branching, scabrous, somewhat 

 hispid. Leaves opposite, sessile, spatulate, lanceolate, dentate, hairy. 

 Flowers axillary and terminal; segments of the involucre ovate-lanceo- 



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