Part 1, 1922] AMBROSIACEAE 31 
A perennial, with a rootstock; stems 4-6 dm. high with erect branches, villous-tomentose 
when young, glabrous and chestnut-brown in age; leaves interruptedly pinnatifid or the upper 
ones simple, densely white-tomentose beneath, silky above; petioles and rachis winged and 
with lanceolate lobes; principal divisions lanceolate, 3-10 cm. long, serrate; inflorescence 
paniculate, leafy below; peduncles of the staminate heads short; involucre rotate, tomentose, 
about 5 mm. in diameter, with 12—14 rounded lobes; paleae of the receptacle linear-lanceolate, 
boat-shaped, 3—5-nerved. longer than the flowers; pistillate head subtended by small ovate 
leaves, 2-flowered; fruit 8 mm. long or more; body spindle-shaped, glandular-puberulent; 
beaks 2, conic, nearly straight, 3 mm. long; spines subulate-conic, nearly straight, 3 mm. long, 
12-15, in about 3 series. 
TYPE LOCALITY: Walnut Creek, between Council Grove and Fort Mann, of the Arkansas 
[centraf Kansas]. 
DISTRIBUTION: Nebraska and Colorado to Northern Texas. 
ILLUSTRATIONS: Britt. & Brown, Ill. Fl. f. 3597; ed. 2. f. 4131. 
VI. Discolores. Perennial herbs, with rootstocks; leaves interruptedly pinnatifid, tomen- 
tose beneath; heads in terminal racemes; staminate involucre with 8-12 short lobes; paleae 
clavate or spatulate, l-nerved; anthers with acuminate or cuspidate incurved tips; fruit 
woody, 2--8-celled; beaks 2—8, short, conic; spines conic, straight or nearly so. 
20. Franseria nivea Rob. & Fern. Proc. Am. Acad. 30: 117. 1895. 
Perennial, 3-10 dm. high; branches white-tomentose; leaves alternate, petioled, inter- 
ruptedly pinnate; blades ovate in outline, white-tomentose on both sides, about 5 cm. long; 
upper part of the petioles and the rachis winged; principal divisions pinnately lobed and 
toothed, with small triangular ones interposed; staminate heads in terminal racemes; peduncles 
about 3 mm. long, recurved; involucre saucer-shaped or nearly rotate, white-tomentose, 4 
mm. wide, with 9-10,short ovate lobes; paleae of the receptacle hyaline, clavate, 1-nerved; 
corolla with brownish angles and margins; pistillate heads in the upper axils and at the base 
of the staminate raceme, sessile, subtended by small leaves; fruit ovoid, 6-7 mm. long, cinere- 
ous, woody, 2-celled; beaks 2, stout, conic, 2 mm. long, somewhat curved but not hooked; 
spines 22-30, in 4 or 5 series, conic, scarcely curved, 1.5 mm. long. 
TYPE LOCALITY: Plains near Casas Grandes, Chihuahua. 
DISTRIBUTION: Known only from the type locality. 
21. Franseria discolor Nutt. Trans. Am. Phil. Soc. II. 7: 345. 
1840. 
Ambrosia tomentosa Nutt. Gen. 2: 186. 1818. Not Franseria tomentosa A. Gray, 1849. 
Xanthidium discolor Delpino, Studi Lign. Anem. 63. 1871. 
Gaertneria discclor Kuntze, Rev. Gen. 339. 1891. 
Gaertneria tomentosa A. Nelson, Bot. Gaz. 34: 34. 1902. Not G. tomentosa Kuntze, 1891. 
A perennial herb, with a creeping rootstock; stem 2-4 dm. high, sparingly strigose; 
leaves interruptedly and irregularly bipinnatifid, elliptic in outline, white-tomentose beneath, 
strigose or glabrate above, 6-15 cm. long; petioles short; rachis winged, with small triangular 
segments interposed between the principal ones; ultimate divisions ovate or triangular, 
toothed; staminate heads in terminal racemes, the pistillate ones in the upper axils; involucre 
of the former green with dark veins, about 5 mm. in diameter, rotate, with about 10 short 
lobes; paleae of the receptacle hyaline, with a single purple vein, spatulate, shorter than the 
corolla; corolla with purple margins and angles; pistillate heads sessile, subtended by small 
bract-like elliptic or lanceolate leaves; fruit woody, strigose, about 6 mm. long, 2-celled; beaks 
2, stout, conic, spreading, 2.5 mm. long, 1.5 mm. thick at the base, the upper lobe hooked; 
spines 8-12, in two or three series, subulate or conic, about 1 mm. long, thick and broadened 
at the base, scarcely hooked. 
TYPE Locality: (of F. discolor) Rocky Mountains near the Colorado of the West [Wyoming]; 
(of A. tomentosa) Upper Louisiana, on the banks of Missouri [South Dakota]. 
DIstRIBUTION: Plains from South Dakota and Nebraska to New Mexico, Arizona, and 
Wyoming. 
ILLUSTRATIONS: Britt. & Brown, Ill. Fl. f. 3596; ed 2. f. 4130; Bull. Agr. Coll. Colo. 23: pl. 9, 10; 
Bull. Nev. Exp. Sta. 22: pl. 2; Bull. Wyo. Exp. Sta. 31: pl. 13. 
