18 NORTH AMERICAN FLORA [VOLUME 33 
6. Ambrosia glandulosa Scheele, Linnaea 22: 157. 1849. 
Ambrosia coronopifolia var. [gracilis, &c.] A. Gray, Bost. Jour. Nat. Hist. 6: 227. 1850. 
Ambrosia artemisiifolia paniculata Blankinship, Rep. Mo. Bot. Gard. 18: 173, mainly. 1907. 
An annual herb, with branched root; stem 5-10 dm. high, terete with scattered appressed 
hairs: leaves pinnatifid or bipinnatifid, strigulose on both sides; petioles 2-3 cm. long; blades 
ovate in outline, 5-10 cm. long; divisions linear-lanceolate, acute or attenuate; staminate 
heads numerous, in racemes terminating the branches; involucre saucer-shaped or slightly 
broadly obconic, hispidulous, crenate, 3 mm. broad; paleae of the receptacle filiform; corolla 
puberulent; pistillate heads few in small clusters in the upper axils; body of the fruit broadly 
obovoid, scarcely 2 mm. long, glandular-granuliferous when young, in age glabrous and smooth; 
beak less than 0.5 mm. long. 
TYPE LOCALITY: River bottom of the Cibolo, 15 miles west of New Braunsfels, Texas. 
DISTRIBUTION: Western Florida to Texas. 
7. Ambrosia elatior 1. Sp. Pl. 987.” 17532 
Ambrosia elata Salisb. Prodr. 175. 1796. 
Ambrosia artemisiifolia T. & G. Fl. N. Am. 2: 291, mainly. 1842. Not A. artemisiifolia L. 1753. 
Ambrosia artemisiifolia quadricornis Kuntze, Rev. Gen. 305. 1891. 
An annual herb, with branched roots; stem 3-10 dm. high, more or less hirsute or his- 
pidulous, branched: leaves bipinnatifid or the upper less divided, hirsutulous-puberulent 
above, strigose beneath, and often hirsute on the veins; petioles 1-3 cm. long; leaf-blades ovate 
in outline; rachis winged, 1-3 mm. broad; segments lanceolate, acute, directed forward; stam- 
inate heads numerous, or in a predominately pistillate form few or none, in racemes terminat- 
ing the branches; involucre slightly oblique, about 3 mm. wide, crenate, hirsutulous or his- 
pidulous or in the western form long-hirsute, broadly obconic; paleae of the receptacle filiform; 
corolla puberulent; pistillate heads in small clusters in the upper axils; body of the fruit 
obovoid, 3 mm. long, hispidulous-strigose, or in age almost glabrous, angled and somewhat 
reticulate; beak subulate, more than 1 mm. long; spines 5-7, subulate, short. 
TYPE LOCALITY: Virginia. 
DISTRIBUTION: Nova Scotia to North Carolina, Arkansas, New Mexico, northern California, 
and Washington; Bermudas; also naturalized in Europe. 
ILLUSTRATIONS: Britt. & Brown. Ill. Fl. f. 3593 (as A. artemisiaefolia); ed. 2. f. 4127; Clark & 
Fletcher, Farm Weeds Can. pl. 24; pl. 55, f. 58; ed. 2. pl. 57; pl. 75, f. 79; Clark & Fletcher, Mauv. 
Herbes Can. pl. 24; pl. 55, f. 58. 
8. Ambrosia diversifolia (Piper) Rydberg, sp. nov. 
Ambrosia artemisiifolia diversifolia Piper, Contr. U. S. Nat. Herb. 11: 551. 1906. 
An annual herb, with branched roots; stem about 5 dm. high, strigose-hirsute; lower 
leaves pinnately divided into oblong or lanceolate divisions, hirsutulous on both sides, some- 
what paler beneath; petioles 1-2 cm. long; blades ovate in outline; upper leaves lanceolate 
or ovate, entire, subsessile, acute; staminate heads numerous, in racemes terminating the 
branches; involucre 5—6-lobed, 4-5 mm. broad, hispid-strigose; lobes broadly triangular, acute; 
paleae of the receptacle filiform; corolla puberulent; pistillate heads in few small clusters or 
solitary in the upper axils; body of the fruit obovoid, about 2.5 mm. long, hirsute-puberulent; 
beak fully 2 mm. long; spines 4-5, sharp, 0.5—0.8 mm. long. 
Type LocaALity: Gravelly banks of Alamota Creek at Alamota, Washington. 
DISTRIBUTION: Washington to Wyoming. 
9. Ambrosia artemisiifolia L. Sp. Pl. 988. 1753. 
Ambrosia absynthifolia Michx. Fl. Bor. Am. 2: 183. 1803. 
Ambrosia heterophylla Muhl.; Willd. Sp. Pl. 4: 378. 1805. 
An annual herb; with branched roots; stem 5-10 dm. high, strigose or in age glabrate; 
leaves pinnatifid or the upper simple, finely strigose; blades ovate in outline; divisions oblong, 
lobed, crenate, or entire, obtuse; staminate heads numerous in terminal racemes; involucre 
saucer-shaped, not acute at the base, fully 4 mm. wide, hispidulous, crenate on the margins; 
paleae of the involucre filiform, slightly clavate at the tip; corolla puberulent; pistillate flowers 
in small clusters in the upper axils; body of the fruit obovoid, 2.5-3 mm. long, slightly puber- 
