FLOWERING PLANTS AND FERNS OF ARIZONA 885 



October. Western Texas to southern Arizona, southward into 

 Mexico. 



The typical form has oblanceolate to spatulate leaves. The less 

 common var. ivae folia (Willd.) Kobinson has broader, lanceolate to 

 oblong-oblanceolate or oval leaves. 



2. HOFMEISTERIA. Arrowleaf 



Much-branched low shrub, glandular-puberulous; leaves opposite or 

 alternate, the blades lanceolate or lance-ovate, 2 to 10 mm. long, very 

 much shorter than the petioles; heads loosely panicled, white, discoid; 

 involucre strongly graduate, of dry few-ribbed phyllaries, the outer 

 ones with acuminate subherbaceous tips; pappus of about 12 bristles, 

 alternating irregularly with much shorter narrow squamellae or 

 bristles. 



1. Hofmeisteria pluriseta A. Gray in Torr., U. S. Kpt. Expl. Miss. 

 Pacif. 4: 96. 1857. 

 Mountains of Yuma (and probably of Mohave) County, 2,500 feet 

 or lower, dry granitic slopes, January to March (sometimes autumn), 

 type from Williams River. Southern Utah and Nevada, western 

 Arizona, southeastern California, and northern Baja California. 



3. CARMINATIA 



Low annual herb; leaves mostly opposite, deltoid-ovate, toothed, 

 thin, slender-petioled; heads discoid, whitish, cylindric, in a terminal 

 leafless virgate panicle; involucre graduated, of thin few-striate phyl- 

 laries; achenes slender; pappus of long-plumose bristles. 



1. Carminatia tenuiflora DC, Prodr. 7: 267. 1838. 



Mountains of Cochise, Santa Cruz, and Pima Counties, 4,000 to 

 5,500 feet, rich soil in canyons, August and September. Western 

 Texas to southern Arizona, south to Central America. 



4. EUPATORIUM. Thoroughwort 



Herbs or low shrubs ; leaves usually opposite ; heads small or medium- 

 sized, usually panicled, discoid, white to lavender, violet, or purple; 

 involucre scarcely to strongly graduated ; achenes 5-ribbed ; pappus of 

 numerous capillary bristles. 



Key to the species 



1. Leaves palmately 3- to 5-cleft, with toothed to pinnatifid divisions; receptacle 



convex; flowers violet 1. E. greggii. 



1. Leaves entire to sharply serrate, not palmately cleft; receptacle flat or essen- 

 tially so; flowers white to purple (2). 

 2. Heads 3- to 6-flowered, sessile or subsessile in small clusters at the tips of 

 usually short branches, forming a thyrsoid panicle; leaves narrowly 

 lanceolate or lance-ovate, not more than 18 mm. wide, very short- 



petioled, acuminate 2. E. solidaginifolium. 



2. Heads 10- to 30-flowered, distinctly pedicellate, not thyrsoid-panicled; 



leaves usually broader (3) . 



3. Leaf blades obtuse, broadly ovate, usually not more than 15 mm. long and 



wide, entire or crenate-serrate, thickish, on petioles 5 mm. long or less; 



plant shrubby, low, puberulous; involucre 3 to 5 mm. high, scarcely 



half as long as the flowers 3. E. wrightii. 



