ORDEii LWJif. — composiim:. ol^ 



3. B. subacau'lis, (Nutt.) Minutely strigose, pubescent at first. 

 Leaves radica], deeply sinuate, bipinnatifid, often l3-rate, somewhat peti- 

 oled ; scapes bearing a single head. Torr. & Gray. 



Genus XXXVII.— PARTHE'XIUM. L. 

 (From parthenoa, a virgin ) 



Involucre 5-leaved, villous. Ray florets ^^miiW^ pistillate, those 

 of the disk staminate. Receptacle 'flat, chaffy. Seed obovate. 

 PapjMS none. 



1. P. iNTEGRiFo'LiTiNr, (L.) Stem ercct, slightly scabrous, striate. 

 Leaves alternate, ovate-lanceolate, unequally toothed, sessile, scabrous, 

 the upper ones amplexicaul. Flowers in terminal corymbs ; ray florets 

 5, small, the exterior chaff, broad. — White or yellowish. If. June — 

 Sept. Upper and middle Car. and Geo. 1 — 2 feet. 



2. P. hysteropho'rus, (L.) Stem hirsute, diffusely branched or de 

 cumbent. Xeave^ bipinnatifid, the uppermost linear, undivided. Heads 

 small, paniculate. — Florida. 



Genus XXXVIII. — I' VA. L. 



(Origin of the name unknown.) 



Involucre 5 — 10-Ieaved. Ray florets pistillate, those of the 

 disk staminate. Anthers not united. Receptacle bristly. Seed 

 obovate. Pappus none. 



1. I, FRUTEs'cENS, (L.) A shrub, with numerous opposite branches, 

 slightly furrowed, somewhat scabrous and pubescent when young. 

 Leaves opposite, lanceolate, attenuate at the base, deeply serrate, sca- 

 brous, of a greenish hue. Flowers axillary, forming terminal panicles ; 

 involucre viscidly pubescent, 6-leaved, leaves nearly round. Jiay fo- 

 rets 5, those of the disk 6 — 7. — Pale purple. ^^ . July — Sept. On the 

 seacoast. 3—8 feet. Marsh Elder. 



2. I. imbrica'ta, (Walt.) Ste)n herbaceous, terete, sliglitly angK^d to- 

 ward the summit, glabrous, becoming purple. Leaves ses^ile, linear- 

 lanceolate, cuneate, succulent, the upper ones usually alternate and 

 entire, the lower frequently opposite and toothed. Flowers axillary, 

 pendulous ; involucre with 6 — 9 fleshy leaves, with the margins lacer- 

 ate. Bay florets 2, those of the disk numerous.- White. U- July — 

 Oct. On the seacoast. 



Genus XXXIX.— AMBRO'SIA. Touin. 

 (From anibrosia, food of the god?.) 



Flowers numerous, staminate florets with the involucre hem 

 ispherical, 1 -leaved, many-flowered. Anthers approximate, but 

 not united. Receptacle naked, pi.stillate florets, with the invo- 

 lucre 1-leaved, entire, or o-toothed, 1-flowered. Corolla none. 

 Styles 2. Fruit a nut formed from the indurated calyx, 1 -seeded. 



1. A. thif'ida, (L.) Sfe)7i erect, rough, hirsute. Leaves usually op- 

 posite, 3-lobed, serrate, the lobes oval-lanceolate, nouminale. hairy, ser- 

 rate. Floioers in small axillary and teiminnl spikes, forming a large 



