130 Flora of the Palouse Region 



0. divaricata Piper, n. comb. (Washingtonia divaricata Britton.) 

 Glabrous or nearly so, 30-60 cm. tall: leaves biternate; leaflets ovate or lan- 

 ceolate, acute or acuminate, thin, coarsely serrate and more or less incised: 

 umbels 2-9-rayed; pedicels mostly 1-2 cm. long: involucels none, fruit 16-20 

 mm. long, bristly-hairy on the ribs, the carpels distinctly beaked, much 

 narrowed at the base. Rich woods, Thatuna Hills. 



0. OCCidentalis Torr. .Stout, more or less puberulent, 40-80 cm. tall: 

 leaves 2-3-ternate; leaflets ovate-oblong, acute, serrate, 4-10 cm. long: umbel 

 5-12-rayed: involucels few or none: fruit 12-16 mm. long, obtuse at base, 

 glabrous, shining, beaked, the ribs prominent and sharp. Cedar Mountain, 

 on moist slopes. 



312. 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 inter- 

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

 side: seed subangular, with plane face. 



S. cicutaefolium Gmel. 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. 



214. ZIZIA. 



Smooth perennials, 30-90 cm. high: leaves simple to ternately 

 compound: involucre none; involucels of small bractlets: flowers 

 yellow, calyx-teeth prominent: stylopodium wanting: styles long: 

 fruit flattened laterally, ovate to oblong, glabrous: central fruit 

 of each umbellet sessile: carpel with filiform ribs: oil-tubes large 

 and solitary in the broad intervals, 2 on the commissural side and 

 a small one in each rib: seed terete, longitudinally grooved beneath 

 the oil tubes. 



Z. COrdata Koch. Glabrous, 30-80 cm. tall: lower leaves simple, cordate, 

 crenately toothed, 2-8 cm. long, sometimes lobed or even teruate, mostly 

 long-petioled; upper leaves short- petioled, palmately compound, of 3-5 

 leaflets, ovate or lanceolate, incised and serrate: fruit ovate, 3 mm. long. 

 Common in copses. 



215. CARUM. 



Smooth erect slender herbs: roots fascicled, tuberous or fusiform: 

 leaves pinnate, with few linear leaflets: involucels of few to many 

 bracts: flowers white: calyx-teeth prominent for the size of the 

 fruit: stylopodium conical: fruit flattened laterally, orbicular to 

 oblong, glabrous: carpels with filiform or inconspicuous ribs: oil- 



