1 84 CORNACEAE. 



Ligusticum leibergi Coult. & Rose. Glabrous; stem stout, branched 

 above, 60-90 cm. tall; leaves large, twice ternate, then pinnate; leaflets ovate 

 or oblong, deeply cleft into narrow sharp-pointed and sometimes serrate 

 lobes; umbel many-rayed; rays 2,5-5 cm. long; involucels wanting; fruit 

 oblong, 4-5 mm. long, the ribs winged. In wet ground especially in the 

 mountains. 



267. PTERYXIA. 



Acaulescent or nearly so, clothed at the base by the persistent 

 leaf -sheaths ; leaves bright green or somewhat pale, clustered at 

 the base, with main divisions ternate, then pinnately finely- 

 dissected into short linear segments; involucre mostly none; 

 involucels of narrow bractlets; flowers yellow or white; calya- 

 teeth evident ; fruit oblong to orbicular, glabrous ; carpel usually 

 strongly flattened dorsally, with wings; stylopodium wanting; 

 oil-tubes several in the intervals; seed-face plane or with a 

 shallow and broad cavity. 



Leaves with pale rigid segments. P. lerebinihina. 



Leaves greener with segments not rigid. P. foeniculacea. 



Pteryxia terebinthina (Hook.) Coult. & Rose. Rootstock simple or but 

 little branched; stems 20-40 cm. high; leaves tripinnate, pale, the ultimate 

 segments rigid, entire or toothed, mucronate, 1-2 mm. long; fruit oval or 

 suborbicular, 7-8 mm. long, the thin wings 2 mm. broad, wavy. Rock Creek, 

 Cotton. A common species in the sagebrush region. 



Pteryxia foeniculacea Nutt. Rootstock much branched, bearing nu- 

 merous stems 30-50 cm. tall; leaves pinnately decompound, very finely dis- 

 sected, green and glabrous, the ultimate segments linear, 2-4 mm. long; fruit 

 oblong, 6-8 mm. long, the wings not as broad as the body, not wavy. In 

 rock crevices on the banks of Snake River and in the Blue Mountains. 



268. SIUM. 



Perennial, growing in water or in wet places; leaflets serrate 

 or pinnatifid; involucres and involucels of numerous narrow 

 bracts; flowers white ; calyx-teeth minute; stylopodium depressed; 

 styles short; fruit flattened laterally, ovate to oblong, glabrous; 

 carpel with prominent corky nearly equal ribs; oil-tubes 1-3, 

 in the intervals, never solitary in all the intervals, 2-7 on the 

 commissural side; seed subangular, with plane face. 



Slum cicutaefoliimi Schrank. Stout, 60-80 cm. tall; leaves pinnate, with 

 7-17 linear or lanceolate serrate acuminate leaflets, these 5-12 cm. long; 

 umbel many-rayed, the rays 2.5-4 cm. long; fruit 3 mm. long, with prominent 

 ribs. Margins of ponds, infrequent. 



Family 66. CORNACEAE. Dogwood Family. 



Trees or shrubs, rarely herbs; leaves simple, alternate or op- 

 posite; flowers regular, perfect, polygamous or dioecious, in 

 cymes or heads; calyx-tube adherent to the ovary; petals and 

 stamens 4, on the margin of an epigynous disk in the perfect 



