RAGWEED FAMILY 829 



obconic. Filaments monadelphous. Corolla of the pistillate flowers wanting. 

 Achenes oblong, flat on the inside, convex or angled on the outside, with thin- 

 scarious, pectinately dentate wings. Pappus rudimentary, of a few small bristle- 

 like scales. 



Upper leaf-blades broadly spatulate, ovate, or roundish. 



Inner bracts 10-15 mm. long; achenes with pectinate margins. 1. D. Wetherillii. 



Inner bracts 6-8 mm. long; achenes with continuous erose margins. 2. D. canescens. 

 Leaves all oblong-lanceolate to linear. 



Fertile flowers solitary in the heads; teeth of the achenes connected by a scarious 

 margin. 3. D. Brandegei. 



Fertile flowers 2 in each head; achenes without scarious margins. 4. D. paniculata. 



1. D. Wetherillii Eastw. Stems strigose; leaves spatulate, hirsute- 

 canescent with appressed hairs; staminate flowers several, longer than the outer 

 bracts; pistillate flowers usually 2; inner bracts hood-shaped, enclosing the 

 achenes, 10-15 mm. long, 10 mm. broad, intricately veined, pitted, glandular- 

 hairy; achenes oblong, mottled with brown, sparingly glandular. Sandy places: 

 s Utah. L. Son. 



2. D. canescens T. & G. Stem intricately branched, 3-10 dm. high, his- 

 pidulous; lower leaves opposite, lanceolate or oblong, coarsely toothed, the upper 

 alternate, round-ovate or orbicular, white with appressed pubescence, 1-3 cm. 

 long, crenate; fertile flowers 2; inner bracts petaloid, orbicular, concave; stam- 

 inate flowers many. Desert washes: se Calif. Ariz. s Utah. L. Son. 



3. D. Brandegei A. Gray. Stem diffusely branched, 3-10 dm. high, canes- 

 cent-hispid; leaves petioled; blades 1-5 cm. long, strigose-canescent, sinuate- 

 denticulate; heads few, some wholly staminate; fertile flowers solitary; inner 

 bracts dilated-cuneate, rather small. Sandy bottoms: s Colo. s Utah Ariz. 

 Son. AM. 



4. D. paniculata Eastw. Stem 3-5 dm. high, branched from the base, his- 

 pid-canescent; leaf -blades sparingly dentate or entire, 1-2 cm. long; heads numer- 

 ous, paniculate; inner bracts large, truncate or obcordate, suborbicular, glandu- 

 lar-ciliate; fertile flowers 2; achenes obovate, 6 mm. long, dark brown, dentate 

 with horny teeth; staminate flowers 9-10. Sandy flats: sw Colo. se Utah. Son. 



5. HYMENOCLEA T. & G. 



Low shrubs. Heads unisexual, monoecious. Involucres of the staminate 

 heads saucer-shaped, of 4-6 more or less united bracts; paleae of the receptacle 

 subtending the outer flowers obovate or spatulate, those of the inner flowers fili- 

 form or none. Filaments distinct; anther-tips blunt; the abortive styles with 

 dilated fimbriate or penicillate tips. Involucres of the 1 -flowered pistillate heads 

 ovoid or fusiform, beaked, with 9-12 dilated and silvery-scarious persistent 

 transverse wings on the lower portion. 



1. H. Salsola T. & G. Low shrubs, much branched, puberulent; leaves 

 alternate, linear-filiform, 1-5 cm. long; heads numerous, paniculate; staminate 

 heads hemispheric, 5 mm. broad, many-flowered; bracts of the pistillate invo- 

 lucre spirally arranged, imbricate, when dry spreading, suborbicular, 6-8 mm. 

 broad, silvery-scarious. Saline soil: s Calif. Xev. s Utah Ariz. L. Son. 



6. AMBROSIA (Tourn.) L. RAGWEED, ROMAN WORMWOOD, 



BITTER-WEED. 



Annual or perennial, often more or less woody, caulescent herbs, mostly 

 monoecious, rarely dioecious. Leaves opposite or alternate, usually much 

 divided, or rarely merely toothed. Staminate heads in terminal spikes or 

 racemes. Involucres saucer-shaped or hemispheric, with 5-12 partly united 

 bracts; receptacle naked or with filiform paleae. Corollas funnelform, 5-lobed. 

 Anthers mucronate at the apex; style rudimentary, brush-like at the apex. Pis- 

 tillate involucres enclosing the single flower, turbinate or subglobose, with several 

 tubercles or spines in a single series. Corolla wanting. Stigmas filiform. Achenes 

 ovoid or obovoid; pappus wanting. 



