Ambrosia. COMPOSITiE. 291 



ering stems erect or ascending, velvety-hirsute at the summit ; leaves nearly 

 all opposite, petioled, rather thick, bipinnatifid, when young hirsute-tomen- 

 tose on both sides ; spikes few, the terminal one much longest; receptacle of 

 the sterile flowers chatfy; fruit (fertile involucre) obovoid, villous when 

 young, unarmed. — DC! jnodr. 5. p. 525. 



Sea-shore, Key West, Mr. Bennett! Mr. Blodgett ! — Whole plant some- 

 what hirsute-canescent, 12-15 inches high. Lower leaves bipinnatifid ; the 

 ultimate segments short; the uppermost occasionally alternate, often simply 

 pinnatifid ; the segments linear, entire or 1-2-toothed. Fertile involucre 

 with about 4 obscure inflexed teeth near the summit. 



3. A. arleinisi(efolia (Linn.): annual; stem sparsely or rather densely 

 villous, or pubescent, paniculately branched ; leaves bipinnatifid, minutely 

 sirigose-pubescent, almost glabrous above, paler and frequently somewhat 

 canescent beneath ; the uppermost simply pinnatifid ; the lower opposite ; 

 petioles ciliate or hirsute; racemes spicate, paniculate; receptacle of the 

 sterile flowers naked ; fertile heads solitary or glomerate along the lower part 

 of the racemes and bracteate, or in the axils of the upper leaves ; fruit ob- 

 ovoid or subglobose, nearly glabrous, pointed, armed with about 6 short acute 

 spines or teeth. — Linn.! spec. 2. p. 988; Lam. ill. t. 16b, f. 1 ; Willd.! 

 spec. 4. p. 376; Ell. sk. 2. p. 477 ,• DC. ! prodr. 5. p. 526. A. elatior, 

 Linn. ! I. c. ; Willd. ! I. c. ; Pnrsh ! ft. 2. p. 581 ; Ell. I. c. ; Bigel. jl. 

 Bost. ed. 2. p. 343 ; Hooh. ! jl.. Bor.-Am. 1. p. 309 ; Darlingt. fl. Cest. p. 

 479 ; DC. ! I. c. A. absyntiiifolia, Michx. ! fl. 2. p. 183. 



ji. cauline leaves 1-2-pinnatifid ; those of the branches nearly sessile; the 

 uppermost lanceolate, undivided, or somewhat lobed at the base. — A. hetero- 

 phylla, Muhl. in Willd. ! spec. 4. p. 378 ; Pursh, I. c. ; DC. I. c. 



y. fertile heads glomerate in the axils of the leaves and on short axillary 

 branchlets or spikes, and more or less racemose or paniculate ; the sterile 

 racemes very short. 



S. less pubescent ; fruit (usually rather smaller) with the spines or teeth 

 very short or obsolete. — A. ]mmcu]ata, Michx. ! fl. 2. p. 183; Willd.! 

 I. c. ; Ell. I. c. ; DC. ! I. c. ; Hook. I. c. partly ? Iva monophylla, Walt. ! 

 Car. p. 232. 



Dry fields and pastures, roadsides, and waste places, Canada ! to Florida! 

 Louisiana ! and Texas ! often a troublesome weed in cultivated grounds. 

 (California, eyi Hook. S^ Am. hot. Beechey.) July-Sept. — Stem 1-3 or 4 

 feet high, at length much branched ; the plant variable as to pubescence, &c. 

 Fruit a line to a line and a half in length ; the spines or teeth certainly varia- 

 ble, and sometimes inconspicuous or almost none. — Of the two Linntean 

 names, the one we have preferred is the most appropriate. — Bitter-weed. 

 Rag-iveed. Hog-weed. 



4. A. coronopifolia : annual ? canescent-strigose, at length much branched, 

 leaves crowded, rigid ; the upper lanceolate or oblong-lanceolate, sessile ; 

 deeply and somewhat remotely pinnatifid or incised; the lower opposite and 

 somewhat bipinnatifid, on short margined petioles; sterile heads in loose 

 spicate racemes, the receptacle chatiy ; fertile heads solitary or somewhat 

 clustered at the base of the sterile spikes and in the axils of the upper leaves; 

 fruit globose-ovoid, turgid, unarmed, obtusely ])ointed, hairy. — A. hispida, 

 Torr. ! in ann. lye. New York, 2. ;/;. 216, doubtless not of Pursh. 



Prairies of Illinois! Missouri, (north to Devil's Lake, il//-. Nicollet!) 

 Louisiana ! and Texas I Aug.-Sept. — Stem erect, 1-5 feet high, often rough 

 or almost hispid. Leaves very numerous, sometimes nearly all opposite, 

 2-5 inches long, clothed with very closely appressed hairs, both sides more 

 or less canescent when young, sprinkled \vith minute resinous globules; the 

 segments ratlier distant, spreading, oblong or lanceolate. Sterile racemes or 

 spikes proportionally shorter than in the preceding; the heads scarcely 



