Part 1, 1922] AMBROSIACEAE 11 
paler beneath, 1-2 dm. long, interruptedly bipinnate with small ovate toothed divisions; in- 
volucre 4 mm. broad; bracts 5-7, somewhat pilose on the back, and ciliate on the scarious 
margins; achenes about 1.5 mm. long, 1 mm. broad, obovate, retuse at the apex. 
TYPE LOCALITY: Near City of Mexico. 
DISTRIBUTION: Federal District and state of Mexico. 
ILLUSTRATION: Deless. Ic. 4: pl. 28. 
7. DICORIA T. & G.; Torr. Bot. Mex. Bound. Surv. 86. 1859. 
Dicoris T. & G.; Torr. in Emory, Notes Mil, Rec. 143, hyponym. 1848. 
Annual or biennial herbs, sometimes somewhat woody at the base. Leaves opposite or 
alternate, petioled, dentate or entire. Heads in leafy panicles, androgynous or some of them 
sometimes wholly staminate. Involucres of 5, mostly distinct, bracts; paleae subtending the 
pistillate flowers more or less accrescent, thin, larger than the bracts; those subtending the 
staminate flowers narrow, filiform with clavate tips. Staminate flowers 5—20; corolla funnel- 
form, sparingly pilose or glandular; stamens monadelphous; anthers oblong, distinct or 
slightly adnate, with acutish tips; pistil rudimentary; style shorter than the filament-tube; 
stigma minute, apparently naked. Pistillate flowers 1-5, marginal; corolla none. Achenes 
flattened dorsiventraily, with a thin pectinate or toothed wing or margin, and somewhat 
keeled on the faces, the outer face convex, the inner flat or concave. 
Type species, Dicoria canescens T. & G. 
Paleae subtending the pistillate flowers very large, in fruit 6-15 mm. long, 
orbicular, strongly concave or hooded, hyaline, reticulate, glandular- 
puberulent. 
Paleae subtending the pistillate flowers strongly hooded, in fruit more than 
lcm. long; achenes with a dentate margin; upper leaf-b!ades obovate 
or spatulate. 
Pistillate flowers usually solitary; body of the achene oblong, 7-9 mm. 
long, nearly 4 mm. wide. 1. D. Wetherillii. 
Pistillate flowers 2-5, usually 3; body of the achene oblanceolate, 6 mm. 
long, 2-3 mm. wide. 2. D. Clarkae. 
Paleae subtending the pistillate flowers not strongly hooded, 6-8 mm. 
long. : 
Achenes margined by pectinate wings fully half as broad as the body; 
upper leaf-blades orbicular. 3. D. canescens. 
Achenes bordered by a toothed margin about one fourth as broad as 
the body; upper leaf-blades oblong. 4. D. oblongifolia. 
Paleae subtending the pistillate flowers not much unlike the involucral bracts 
but thinner and larger, 4 mm. long, elliptic, not reticulate, strigose or 
hispidulous. 
Leaf-blades suborbicular; stem hispidulous; hairs with pustulate bases. 5. D. hispidula. 
Leaf-blades lanceolate; stem strigose. 
Pistillate flowers usually 2; margins of the achene irregularly dentate, 
with teeth horny at the base. 6. D. paniculata. 
Pistillate flowers usually solitary; margins of the achene with pectin- 
ate wings. 7. D. Brandegei. 
1. Dicoria Wetherillii Eastw. Proc. Calif. Acad. II. 6: 299. 1896. 
An annual, resembling D. canescens; stem canescent; upper leaves spatulate, hirsute- 
canescent; heads numerous in leafy panicles; involucre hemispheric, 3-4 mm. broad; bracts 5, 
elliptic, white-hispid; paleae subtending the pistillate flowers membranous, intricately veined, 
glandular-pubescent, orbicular, hooded, 10-15 mm. long, 10 mm. broad, enclosing the achenes; 
staminate flowers several; corollas funnelform, pubescent, longer than the bracts; pistillate 
flowers usually solitary; achenes oblong, 8-9 mm. long, 4 mm. wide, motiled with brown, with 
scattered hairs and yellow glands; margin pectinate, somewhat scarious, about 0.5 mm. wide. 
TYPE LOCALITY: Along San Juan River [Colorado or Utah]. 
DISTRIBUTION: Known only from the type locality. 
2. Dicoria Clarkae P. Kennedy, Muhlenbergia 4: 2. 1908. 
A stout herbaceous annual or biennial; stem 5-8 dm. high, with spreading branches, 
grayish, hispidulous; leaves alternate, petioled, 3-5 cm. long, 2—4 cm. wide, the blades 
ovate, strongly hispid, entire or sinuate-dentate; heads in leafy panicles; involucre 5-6 mm. 
broad; bracts 5, oblong or ovate-lanceolate, grayish-pubescent; paleae subtending the pistil- 
