Part 1, 1922] AMBROSIACEAE 13 
ribbed or the upper l-ribbed, canescent, hispid-strigose; heads in leafy panicles; involucre 
about 4 mm. broad, campanulate; bracts 5, oblong, distinct; paleae subtending the pistillate 
flowers orbicular, truncate or retuse, glandular, membranous at the edge, ciliate and slightly 
strigose; those subtending the staminate flowers filiform-clavate; staminate flowers 9 or 10, the 
corolla slightly hispid; pistillate flowers 2; achenes oblong, hairy, 6 mm. long, 2 mm. wide, 
dark-brown, irregularly dentate on the margin with horny teeth. 
TYPE LOCALITY: Sandy flats along the San Juan River, near the junction of McEImo Creek, 
southwestern Colorado. 
DISTRIBUTION: Southwestern Colorado and northwestern New Mexico. 
ILLUSTRATION: Proc. Calif. Acad. II. 6: pl. 45. 
7. Dicoria Brandegei A. Gray, Proc. Am. Acad. 11: 76. 1876. 
A cinereous herb; stem erect, 3-10 dm. high, with nearly erect branches, strigose-canes- 
cent; leaves mostly alternate, short-petioled, lanceolate, strigose-canescent, entire or slightly 
dentate, 3-4 cm. long, triple-ribbed; heads numerous in leafy panicles; involucre 3-4 mm. wide; 
bracts 5, elliptic, canescent-strigose; paleae subtending the pistillate flower elliptic or oblong, 
thin but not scarious, about half longer than the bracts, hispidulous; those subtending the 
staminate flowers few, filiform with clavate tips; staminate flowers 6-12; corolla funnelform, 
sparingly pilose; style shorter than the filament tube; stigma minute; pistillate flower solitary 
or none; achene flat, oblong, hispidulous; marginal wing cleft into toothed lobes, 6 mm. long. 
TYPE LOCALITY: Montezuma Creek, near the southwestern corner of Colorado. 
DISTRIBUTION: Southwestern Colorado, southern Utah, and Arizona. 
Tribe 2. AMBROSIEAE. Herbs or shrubs with alternate or opposite leaves. 
Heads unisexual. Staminate heads nodding, open; involucre of few, distinct 
or united bracts, in a single series; receptacle with narrow paleae. Pistillate 
heads erect or spreading, of few to many bracts, in one or more series, but 
wholly united and enclosing the flowers, forming a 1-—7-celled nut or bur, 
usually covered with tubercles or spines, and with 1—7 beaks, from which the 
long stigmas protrude; pistillate flowers without corollas. 
Involucral bracts of the staminate heads more or less united; receptacle flat 
or slightly convex; stigmas of the sterile flowers peltate, penicillate 
or fimbriate. 
Involucres of the pistillate heads with 6-12 dilated, scarious, blade- 
like transverse wings. 8. HyMENOCLEA. 
Involucres of the pistillate heads with one or more series of tubercles 
or spines, or rarely unarmed. 
Tubercles or spines in a single series; beak of the fruit truncate or 
equally 3—5-toothed with straight teeth. 
Pistillate head with a single flower; involucre armed with tuber- 
_cles or short spines or rarely unarmed. 9. AMBROSIA. 
Pistillate head 2—5-flowered; involucre armed with long diver- 
gent spines. 10. ACANTHAMBROSIA. 
Tubercles or spines in several series; beak or beaks of the fruit 2- 
toothed; teeth usually more or less incurved, the outer much 
longer. 11. FRANSERIA. 
Involucral bracts of the staminate heads distinct; receptacle elongate; 
stigmas of the sterile flowers small, unappendaged; beaks 2, 2- 
lipped asin Franseria. 12: XANTHIUM. 
8. HYMENOCLEA T. & G.; (Torr. in Emory, Notes Mil. Rec. 143, 
hyponym. 1848) A. Gray, Mem. Am. Acad. II.4: 79. 1849. 
Shrubs, with narrow linear leaves. Staminate heads nodding; involucre saucer-shaped, 
4—6-lobed; outer paleae obovate or spatulate, the inner ones filiform or wanting; corolla hyaline, 
funnelform, pubescent, 5-toothed; filaments distinct above; anthers oblong with incurved tips; 
rudimentary style slender; stigmas peltate, fimbriate or penicillate. Pistillate heads erect; 
involucre wholly enclosing the single flower, fusiform, surrounded at the middle and below by 
5-12 flat membranous blade-like transverse wings, and produced into a truncate beak at the 
apex. 
