20 NORTH AMERICAN FLORA [VOLUME 33 
ous, terminating the branches; involucre oblique, broadly obconic, about 2.5 mm. broad, 
crenate on the margins, hispidulous, the hairs short, with conspicuous pustulate bases; pistil- 
late heads solitary or 2 or 3 together in the axils of the upper leaves; body of the fruit 2.5 mm. 
long, obovoid, rugose, hirsutulous; beak nearly 1 mm. long; tubercles 4-6, very short but acute. 
TYPE LOCALITY: Between San Fernando and Matamoros, Tamaulipas. 
DISTRIBUTION: Louisiana to New Mexico and Tamaulipas. 
14. Ambrosia coronopifolia T. & G. Fl. N. Am. 2: 291. 1842. 
Ambrosia hispida Torr. Ann. Lye. N. Y. 2: 216. 1827. Not A. hispida Pursh, 1814. 
Ambrosia psilostachya A. Gray, Syn. F]. N. Am. 12: 250, mainly. 1884. Not A. psilostachya DC. 
1836. 
A perennial herb, with a creeping rootstock; stem 3-10 dm. high, branched above, striate, 
hirsute with appressed or ascending hairs; leaves ovate in outline, pinnatifid, subsessile or the 
lower with short winged petioles, strigose and glandular-granuliferous on both sides, the 
divisions lanceolate or oblong-lanceolate, acute, or those of the lower leaves obtuse, often 
lobed; staminate heads very numerous, in racemes terminating the branches; involucre ob- 
lique, broadly obconic, 3-3.5 mm. broad, slightly shorter than the flowers, hispid-strigose, 
crenate on the margins; paleae of the receptacle filiform; corolla puberulent; pistillate heads 
solitary or 2 or 3 together in the axils of the upper leaves; body of the fruit 3 mm. long, obovoid, 
indistinctly rugose, hirsute; beak conic, scarcely more than 0.5 mm. long; spines wanting or 
1-4, very short and blunt. 
TYPE LOCALITY: Prairies of Illinois. 
DISTRIBUTION: Illinois and Michigan to Saskatchewan, Idaho, and northern Mexico; introduced 
in Connecticut. 
ILLUSTRATIONS: Britt. & Brown. Ill. Fl. f. 3594; ed. 2. f. 4128; Clark & Fletcher, Farm Weeds 
Can. pl. 55. f. 59; Clark & Fletcher, Mauv. Herbes Can. pl. 55. f. 59 (all as A. psilostachya). 
15. Ambrosia californica Rydberg, sp. nov. 
Ambrosia psilostachya A. Gray, Bot. Calif. 1: 344, in part. 1876. 
A perennial herb, with a creeping rootstock; stem 3-10 dm. high, hirsute or pilose, with 
spreading hairs; leaves subsessile, pinnatifid, long-strigose and somewhat glandular-granuli- 
ferous on both sides; leaf-blades ovate in outline; segments linear-lanceolate or lanceolate in 
outline, acute, and entire, toothed, or incised; staminate heads numerous, in racemes at the 
ends of the branches; involucre broadly turbinate, shorter than the flowers, 3-4 mm. broad, 
pilose, usually dark-colored; paleae of the receptacle filiform; corollas puberulent; pistillate 
heads in the upper axils; body of the fruit elongate-obovoid, glandular-puberulent and slightly 
pilose towards the end, somewhat reticulate; beak fully 0.5 mm. long; spines 4-7, short, conic, 
acute. 
Type collected at Santa Barbara, California, 1865, Torrey 226 (herb. N. Y. Bot. Gard. and 
Columbia Univ.). : 
DIsTRIBUTION: California, from Cape Mendocino south, and Humbolt County, Nevada. 
16. Ambrosia pumila (Nutt.) A. Gray, Proc. Am. Acad. 17: 217. 
1882. 
Franseria pumila Nutt. Trans. Am. Phil. Soc. II. 7: 344. 1840. 
Hemiambrosia heterocephala Delpino, Studi Lign. Anem. 61. 1871. 
A perennial herb, with a rootstock; stems 1-2 dm. high, silky-canescent; leaves mostly 
alternate, bipinnatifid or tripinnatifid, grayish silky-canescent; petioles 2-3 em. long; blades 
broadly ovate in outline; divisions linear or linear-oblong; staminate heads rather few in term- 
inal racemes; involucre saucer-shaped, 4 mm. broad, crenately 5—6-toothed on the margin, 
canescent; paleae of the receptacle few, linear, with spatulate pubescent tips; corolla glandular- 
puberulent; pistillate heads in small clusters in the upper axils; fruit pubescent, obovoid, un- 
armed, 2 mm. long. 
TYPE LOCALITY: San Diego, California. 
DISTRIBUTION: Southern California and Tower California. 
