8 NORTH AMERICAN FLORA [VoLUME 33 
2. LEUCIVA Rydberg, gen. nov. 
Tomentose annuals, with alternate pinnately cleft leaves. Heads numerous, nodding, 
in panicles, ebracteolate.. Involucre hemispheric; bracts 5 or 6, distinct. Paleae of the re- 
ceptacle obsolete. Staminate flowers 8-12; corolla funnelform, hyaline, 5-toothed; anthers 
oblong, with acute incurved tips; style as long as the stamens; stigma peltate, fimbriate. 
Pistillate flowers usually 5, marginal, sometimes wanting; corolla a short truncate tube. 
Achenes terete, pear-shaped, neither flattened, margined, nor winged. 
Type species, Iva dealbata A. Gray. 
1. Leuciva dealbata (A. Gray) Rydberg 
Iva dealbata A. Gray, Pl. Wright. 1: 104. 1852. 
A tomentose annual; stem 3-6 dm. high, slightly angled, villous-tomentose; leaves al- 
ternate, subsessile, 5-10 cm. long, oblanceolate or cuneate-obovate in outline, pinnately 3-7- 
cleft, tomentose on both sides; divisions lanceolate or the terminal one ovate; heads short- 
peduncled, in terminal and axillary panicles; involucre hemispheric, about 3 mm. broad, 
villous; bracts 5 or 6, obovate, scarious-margined, somewhat villous without; staminate flow- 
ers 8-12; corolla hyaline, glandular-puberulent; achenes pear-shaped, glandular-muricate, 
about 1 mm. long. 
TYPE LOCALITY: Between Limpia and Rio Grande, New Mexico [now Texas]. 
DISTRIBUTION: Texas, New Mexico, Coahuila, and Chihuahua. 
3. OXYTENIA Nutt. Jour. Acad. Phila. II. 1: 172. 1848. 
Monoecious shrubs, with canescent leaves pinnatifid with linear-filiform divisions. In- 
florescence paniculate. Heads androgynous. Involucre of 5 distinct bracts. Receptacle 
with narrow paleae subtending the staminate flowers or these wanting in thecenter. Staminate 
flowers 10-20; corolla elongate-funnelform, pubescent, 5-toothed; stamens monadelphous; 
anthers distinct or slightly coherent, oblong, with acute incurved tips; pistil rudimentary; 
style filiform; stigma peltate, hispidulous. Pistillate flowers about 5, marginal; corolla repre- 
sented by a fleshy annular ring; ovary villous; style elongate; stimgas oblong, Achenes 
obovate, turgid, villous. 
Type species, Oxytenia acerosa Nutt. 
1. Oxytenia acerosa Nutt. Jour. Acad. Phila. II.1:172. 1848. 
A shrub 1-2 m. high, with erect, striate and grayish-strigose branches; leaves canescent, 
pinnatifid with 3-7 linear-filiform divisions, 5-10 cm. long, 1 mm. wide, or the upper entire, 
filiform; heads very numerous, paniculate; involucre hemispheric, 5 mm. broad; bracts 5, 
canescent, ovate, abruptly short-acuminate; paleae of the receptacle slender with cuneate 
dilated tips, villous; achenes obovate, villous, compressed, 2 mm. long. 
TypE LOCALITY: “Rocky Mountains, near Upper California.” 
DISTRIBUTION: Dry and sandy places, southwestern Colorado, southern Utah, Arizona, and 
southeastern California. 
, 4. CHORISIVA (A. Gray) Rydberg, gen. nov. 
Iva § Chorisiva A. Gray, Syn. Fl. N. Am. 12: 247. 1884. 
Diffusely branched annuals, with alternate, pinnately cleft, canescent leaves. Heads 
solitary, scattered along the leafy branches, but mostly supra-axillary. Involucre hemis- 
pheric; bracts 3, with foliaceous oblong appendages; paleae of the receptacle present; those 
subtending the pistillate flowers broad, orbicular, hyaline, more or less embracing the achenes; 
those of the staminate flowers filiform. Staminate flowers 8-10; corolla funnelform, villous; 
filaments monadelphous; anthers distinct, oblong, with acute incurved tips; style nearly as 
long as the stamens; stigma peltate, penicillate. Pistillate flowers marginal, usually 3, rarely 
4: corolla represented by a truncate tube; style and stigmas elongate. Achenes obovate, 
somewhat compressed, the outer face convex and muriculate, the inner flat or concave and 
tubercled. 
Type species, Iva nevadensis M. E. Jones. 
