COMPOSITAB 139 



in commemoration of some obscure Botanist, named Ambrose; but 

 the authorities are otherwise. 



2. A. artemiiae folia, L. Stem rather slender and diffusely 



branched, villous and roughish ; leaves bipinnatifid, the upper ones 



simply pinnatifid. 



A. elatior. L. $ Fl. Cestr. ed. 2. p. 479. 



ARTEMISIA-LEAVED AMBROSIA. Bitter-weed. Rag-weed. 



Stem 1 to 3 or 4 feet high, usually bushy. Leaves 2 to 4 inches long; petioles % 

 of an inch tt> an inch in length, mostly ciliate with long white hairs. Staminate 

 Jieads small, in terminal slender spicate racemes. Pistillate florets in axillary 

 bracteate clusters, below the staminate racemes : sometimes the heads are dimcous, 

 i. e. the terminal racemes (or rather interrupted spikes, in that case,) as well as 

 the clusters beneath, are all pistillate! and the flowers in small sessile bracteate 

 clusters. Involucre of the pistillate florets scarcely ribbed. Akene mucronate, dark 

 brown. 

 2 lab. Cultivated fields, and pastures : common. Fl. Aug. Fr. Octo. 



Obs. This worthless weeH is apt to spring up wherever the ground 

 is broken with the plough, and to be particularly abundant among 

 the stubble, after a crop of wheat: but, if the land be good, the 

 plant seems to be smothered- or choked out, the next season, by the 

 clover and grasses. 



2OO. XA&'THIUM, Tournef. 

 [Qr. JTanthos, yellow ; a color said to be afforded by the plant.] 

 Heads monoicous, in spicate clusters, the staminate above, many- 

 flowered. Involucre of the staminate heads subglobose ; scales dis- 

 tinct; florets clavate. Pistillate heads 2-flowered, the involucre 

 oblong, closed, coriaceous, armed with hooked prickles, and 1 or 2 

 strong beaks at apex ; corolla filiform. Akenes oblong, compressed. 

 Annuals : leaves alternate, petiolate, lobed, or dentate. 



1. X. strumarium, L. Leaves broad-ovate, somewhat 3-lobed; peti- 

 oles not spinose at base ; pistillate involucre with 2 strong straight 

 beaks at apex. 



SCROFULOUS XASTTHIUM. Clot-weed. Cockle-bur. 



Stem 1 to 3 feet high, angular, branching, scabrous-pubescent. Leaves 3 to 6 

 inches in length, and nearly as wide as long, subcordate at base, but cuneately 

 produced in the centre, at the junction of the 3 principal nerves ; petioles 2 to 4 

 i aches long. Heads of flowers in axillary racemose clusters, the pistillate ones at 

 the base of the racemes. 

 Sab. Farm-yards; roadsides, Ac. Nat of Europe. Fl. Aug. JFV. Octo. 



Obs. This is evidently, I think, a stranger, here, and is an ob- 

 noxious weed, though not disposed to spread rapidly. The burs 

 are a great annoyance, in the fleeces of sheep. 



2. X. spindsum, L. Leaves ovate-lanceolate, hoary-tomentose be- 

 neath; petioles triply spinose at base; pistillate involucre with 

 a single inconspicuous beak at apex. 



SPINOSE XANTHIUM. Thorny Clot-weed. 



Stem 2 or 3 feet high, terete, striate, pubescent, branched. Leaves 1 to 3 inches 

 long, sometimes 3-lobed, or with a lobe-like tooth on each side, narrowed at base to 

 a short pubescent petiole, on each side of which is a triple or 3-forked yellowish 



