676 MISC. PUBLICATION 4 2 3, U. SL DEPT. OF AGRICULTURE 



*2. Centaurium exaltatum (Griseb.) W. F. Wight, Contrib. U. S 

 Natl. Herbarium 11: 449. 1906. 



Erythraea dougJasii A. Gray, Bot. Calif. 1: 480. 1876. 



The only specimen seen by the writers that is surely of this species 

 and that may have come from Arizona is one labeled "Southern 

 Utah, northern Arizona, etc." (Palmer in 1877). Nebraska to 

 Washington, Utah, and California. 



3. Centaurium nudicaule (Engelm.) Kobinson, Amer. Acad. Arts and 

 Sci. Proc. 45: 397. 1910. 



Erythraea nudicaulis Engelm., Amer. Acad. Arts and Sci. 



Proc. 17: 222. 1882. 



Santa Catalina and Baboquivari Mountains (Pima County), 3,000 

 to 4,000 feet, along streams, April and May, type from the Santa 

 Catalina Mountains (Pringle in 1881). Southern Arizona and 

 Baja California. 



Specimens collected at Willow Spring, southern Apache County 

 (Palmer in 1890), and in northeastern Pinal County (Smith 12994), 

 seem to be intermediate between this species and C. exaltatum. 



2. GENTIANA. Gentian 



Plants annual or perennial ; stems mostly erect, simple or sparingly 

 branched; flowers terminal or axillary, solitary or in cymose clusters, 

 these often forming narrow leafy panicles; coroUa cylindric, funnel- 

 form, or salverform, usually with folds, these often extended into 

 teeth or fringed appendages between the lobes; stamens attached to 

 the tube of the corolla; stigmas 2, or the stigma 2-lobed. 



The medicinal use of gentian root is of great antiquity, but the 

 drug is very mild and probably only a stimulant of gastric secretions. 

 Many of the species are very beautiful in flower. 



Key to the species 



1. Flowers terminal and solitary; plant annual; stems not more than 12 cm. 

 long; corolla 9 to 15 mm. long, the lobes entire or nearly so; alpine 

 plants (2). 

 2. Leaves appressed to the stem, these and the calyx lobes with conspicuous 

 white scarious margins; flower nearly sessile, or the peduncle not more 

 than 1 cm. long; corolla salverform with a long, slender tube and spread- 

 ing lobes, whitish or greenish purple, with broad, emarginate folds in 

 the sinuses 1. G. fremontii. 



2. Leaves not appressed or scarious-margined; flower borne on a peduncle 2 to 



8 cm. long; corolla nearly cylindric, the tube about as wide as the throat, 

 the lobes erect, pale blue (sometimes ochroleucous?) without folds in 



the sinuses, fringed in the throat 2. G. monantha. 



1. Flowers clustered or, if terminal and solitary, then the corolla more than 20 

 mm. long (3). 



3. Corolla folded in the sinuses, the terminal portion of the folds free and bifid 



or irregularly dentate or laciniate; plant perennial; leaves thickish; 



corolla usually violet (4). 

 4. Flowers solitary or few (not more than 5), terminal and subterminal; 

 corolla campanulate-funnelform, 30 to 40 mm. long, rich violet with 

 a green band externally between each pair of folds extending nearly 

 to the apex, the folds 2-cleft at apex and nearly equaling the lobes. 



3. G. PARRYI. 



