354 GENTIANACEAE 



calyx, the lobes broadly oblong-ovate, 4-6 mm. long, anthers 1.5 mm. long, the cells of even 

 length at base and approximate below the filament attachment; stigmas broadly fan-shaped, 

 widely spreading, style cleft a short distance below the stigma. 



Low ground, mainly Upper Sonoran Zone; California Coast Ranges, from Mendocino County to San Luis 

 Obispo County and on Santa Cruz Island. Type locality: West Berkeley, California. April-July. 



6. Centaurium exaltatum (Griseb.) W. F. Wight. Great Basin Centaury. 



Fig. 3793. 



Cicendia exaltata Griseb. in Hook. Fl. Bor. Amer. 2: 69. pi. 157. 1838. 

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

 Erythraea exaltata Coville, Contr. U.S. Nat. Herb. 4: 150. 1893. 

 Centaurion exaltatum W. F. Wight, Contr. U.S. Nat. Herb. 11: 449. 1906. 



Stems simple or usually much-branched, 7-35 cm. high. Basal leaves similar to the lower 

 cauline, 2-3 cm. long, oblong-elliptic to oblong-lanceolate, acute, the upper smaller, linear- 

 lanceolate ; flowers on pedicels 1-4 cm. long, terminating the branches and in the forks ; calyx- 

 lobes subulate, 8-10 mm. long, the margins scarious below; corolla pale pink, sometimes white, 

 the tube 8-10 mm. long, contracted above the ovary, the lobes 3-4 mm. long, oblong, obtuse; 

 anthers oblong, slightly over 1 mm. long ; stigma cleft to the base, the lobes fan-shaped, slightly 

 spreading ; capsule fusiform ; cylindric, 7 mm. long. 



Moist places, Upper Sonoran Zone; eastern Washington and eastern Oregon, south, east of the Sierra 

 Nevada, to the deserts of southern California and adjacent Lower California, east to Idaho, Nevada, Utah, and 

 Arizona. Type locality: "Between the Kettle Falls and Narrows of the Columbia River." Collected by 

 Douglas. May-Aug. Desert Centaury. 



7. Centaurium trichanthum (Griseb.) Robinson. Alkali Centaury. Fig. 3794. 



Erythraea trichantha Griseb. Gen. & Sp. Gent. 146. 1839. 

 Centaurodes trichanthum Kuntze, Rev. Gen. PI. 2: 426. 1891. 

 Centaurium trichanthum Robinson, Proc. Amer. Acad. 45: 397. 1910. 



Stems simple below or occasionally branched to the base, corymbosely branched above, 

 8-35 cm. high. Leaves ovate to lanceolate or narrowly oblong, 1-3 cm. long ; flowers commonly 

 numerous in open or sometimes crowded cymes, subsessile or commonly on pedicels, 4-10 mm. 

 long, or in the form with congested inflorescence sessile or subsessile ; calyx-lobes 8-14 mm. long, 

 subulate, neither scarious margined nor keeled; corolla pink with a creamy white throat, the 

 tube slender, well exceeding the calyx-lobes and constricted above the ovary, the lobes 8-10 mm. 

 long, 2.5-4 mm. broad; anthers linear, 3.5 mm. long; stigma-lobes closely appressed, 0.5 mm. 

 high, narrowly cuneate, and not as broad as long ; style not cleft below the stigma-lobes. 



Moist places usually along streams. Upper Sonoran and Transition Zones; California Coast Ranges from 

 Siskiyou County to San Mateo County. Type locality: California. Collected by Douglas. May-Aug. 



8. Centaurium venustum (A. Gray) Robinson. Canchalagua or Beautiful 



Centaury. Fig. 3795. 



Erythraea venusta A. Gray, Bot. Calif. 1: 479. 1876. 

 Centaurodes venustum Kuntze, Rev. Gen. PI. 2: 426. 1891. 

 Centaurium venustum Robinson, Proc. Amer. Acad. 45: 397. 1910. 



Stems usually simple below, corymbosely branched above, 8-50 cm. high. Leaves ovate to 

 narrowly oblong, 1-2 cm. long ; flowers numerous except in dwarf plants, those in the principal 

 forks on pedicels 15-25 mm. long, the others on shorter ones; calyx-lobes 8-9 mm. long, 

 subulate; corolla pink, and usually with red spots on the white throat, the lobes lanceolate to 

 oblong-ovate, 5-12 mm. long and up to 6 mm. broad, the tube about as long as the lobes ; anthers 

 4-6 mm. long; stigma-lobes broadly fan-shaped, broader than long, diverging; style cleft for a short 

 distance below the stigma ; seeds globular. 



Dry slopes and mesas, often among shrubs, Sonoran Zones; Sierra Nevada foothills from Butte County 

 southward to cismontane southern California and the western rim of the deserts, and adjacent Lower California. 

 Type locality: southern California, but no definite station cited. May-Aug. The plants north of Kern County 

 have smaller flowers and smaller stigmas. Perhaps they should be considered a geographical subspecies. 



3. EUSTOMA Salisb. Parad. Lond. 1 : pi. 34. 1806. 



Annual herbs with erect usually branched glaucous stems and opposite sessile or 

 clasping leaves. Flowers solitary or paniculate, axillary or terminal, blue, purple or 

 white. Calyx deeply cleft into 5-6 lanceolate, acuminate and keeled lobes. Corolla 

 broadly campanulate, divided into 5-6 oblong or obovate lobes, convolute in the bud and 

 usually erose-denticulate. Stamens 5-6, inserted on the corolla throat, the filaments fili- 

 form; anthers oblong, versatile, becoming slightly recurved or remaining straight after 

 anthesis. Ovary 1-celled; style filiform; stigma 2-lobed, the lobes lamellate. Fruit a 

 2-valved, oblong or ovoid capsule. Seeds numerous, small, faveolate. [Name Greek, 

 meaning open-mouth, in reference to the corolla.] 



A genus of 4 species, native of the southern United States, Mexico, West Indies, and northern South Amer- 

 ica. Type species, Eustoma silenifolium Salisb. 



