586 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



1. Plant annual; stem solitary, erect, up to 50 cm. long, often loosely pilose above ; 

 the pubescence in lines; herbage bright green; leaves distinctly petioled, 

 the blades rhombic-lanceolate, up to 20 mm. wide, serrulate, acuminate 

 at apex; flowers solitary or in few-flowered clusters; pedicels usually not 

 decurved; corolla 6 to 9 mm. long, the lower petal at least twice as long as 

 the others, with a flat blade 2. H. attenuatus. 



1. Hybanthus verticillatus (Ortega) A. Nels. in Coult., New MaD. 



Rocky Mount. 323. 1909. 



Viola verticillata Ortega, Hort. Matr. Dec. 50. 1797. 

 Calceolaria verticillata Kuntze, Rev. Gen. PL 1: 41. 1891. 



Gila and Yavapai Counties to Cochise, Santa Cruz, and Pima 

 Counties, 4,000 to 5,500 feet, dry open plains and mesas, May to 

 September. Kansas and Colorado to Arizona and Mexico. 



2. Hybanthus attenuatus (Humb. and Bonpl.) G. K. Schulze, Notizbl. 



Bot. Gart. u. Mus. Berlin 12; 114. 1934. 



Ionidium attenuatum Humb. and Bonpl. in Roem. and Schult., 

 Syst. Veg. 5: 402. 1819. 



Mule Mountains (Cochise County), Santa Rita and Baboquivari 

 Mountains (Pima County), about 4,000 feet, rich soil in canyons, 

 August to September. Southern Arizona to Central America. 



2. VIOLA. Violet 



Plants perennial, with rootstocks, caulescent or acaulescent; leaf 

 blades lanceolate to round-reniform, entire or dentate; flowers on long 

 2-bracted peduncles, all or some of them large and showy, the corolla 

 violet, yellow, or whitish, the lower petal spurred or deeply saccate 

 at base; inconspicuous cleistogamous flowers also often present; sta- 

 mens closely surrounding the ovary. 



Key to the species 



1. Plants strictly acaulescent, the leaves and scapes from rather stout, horizontal 

 to erect rootstocks; herbage glabrous or sparsely pubescent; corolla nor- 

 mally violet, the spur short and stout (2) . 

 2. Leaf blades round-reniform, crenate 1. V. nephrophylla. 



2. Leaf blades pedately parted or divided with narrow divisions. 



2. V. PEDATIFIDA. 



1. Plants caulescent or soon becoming so (3). 



3. Corolla yellow, often tinged with brown or purple; plants subacaulescent 



when young; herbage pubescent or puberulent; blades of the upper 

 leaves lanceolate or rhombic-lanceolate (4) . 

 4. Capsules glabrous or glabrate; leaf blades entire or sparingly denticulate; 

 upper petals usually yellow on the back _ 3. V. nuttallii. 



4. Capsules puberulent; leaf blades, at least the basal ones, conspicuously 



dentate; petals (at least the 2 upper ones) brown on the back. 



4. V. VENOSA. 

 3. Corolla blue or white, sometimes with a yellow eye (5). 



5. Spur cylindric, one-third as long as to nearly equaling the blade of the 



petal; corolla blue; plant subacaulescent at first; flowering stems from 

 creeping rootstocks, numerous, diffuse, commonly not more than 10 

 cm. long; leaf blades ovate to suborbicular, short-cuneate to stibcordate 

 at base, crenulate, puberulent or nearly glabrous..- 5. V. adunca. 

 5. Spur saccate, much less than one-third as long as the blade of the petal; 

 petals white, purple veined, and usually tinged with purple on the 

 back; plant strongly caulescent; flowering stems from short thick 

 rootstocks, few, erect or ascending, commonly 20 to 30 cm. long; 

 leaf blades triangular-ovate to suborbicular, deeply cordate at base, 

 crenate, puberulent on both faces or glabrous beneath. 



6. V. CANADENSIS. 



