142 PROCEEDINGS OF THE AMERICAN ACADEMY 



peduncles six to fifteen inches high : leaves pinnate, oblong in outline, 

 the ovate segments half an inch long, deeply toothed or pinnatifid or 

 pinnate with narrow divisions : involucels small : flowers yellow : calyx- 

 long, narrowly winged : vittae distinct, solitary, 4 on the commissure. — Wash- 

 ington Territory and Idaho to the Sacramento. 



2. P. NcTTALLii, Watson. Very similar: leaflets orbicular or ovate, ob- 

 tuse : fruit sliorter and more ovate, very narrowly winged ; vittaj obscure, 3 or 4 

 in the intervals and 4 to 6 on the commissure. — Bot. Iving's Kep. 128. P. lati- 

 folium, Nutt. Oregon and N. Nevada. 



-*- t- Leaves pinnate or bipinnate; leaflets narrowly linear : involucels present. 



3. P. GRAVEOLENS, Watsou, 1. c. Scapc 6 to 18 inches high, a little exceed- 

 ing the leaves : fruit oblong, 4 or 5 lines long, narrowly margined ; calyx-teeth 

 evident; vittae about 2 in tlie intervals, 4 on the commissure. — Musetunm teitui- 

 foliiun. Hook, in Lond. Jour. Bot. 6. 237, not Nutt. Mountains of Utah and 

 Colorado ; subalpine. 



* * Caulescent (often acaulescent in n. 4) : involucels mostly present : vittae 

 solitary, except in n. 8. 



•*- Leaflets linear, entire. 



4. P. TRITEKXAT0M, Nutt. Finely puberulent, often tall : leaves blternate 

 or ternate quinate ; segments acute : fruit oblong, narrower below, 3 or 4 lines 

 long, very narrowly winged, distinctly ribbed, rarely pubescent ; vittie distinct, 



2 on the commissure. — P. leptocarpiun, Nutt., the acaulescent form. Washing- 

 ton Territory and Idaho to Northern California. 



5. P. SIMPLEX, Nutt. Similar : leaves ternate or biternate : fruit orbicular, 



3 to 6 lines long, emarginate at each end ; wings broader than the body ; ribs 

 prominent. — Watson, 1. c. 129. P. tn'lernatam, var. plati/carpum, Torr. in 

 Stansb. Rep. 389. Montana to N. Arizona. 



6. P. AMBiGUUM, Nutt. Glabrous, often low: petioles much dilated at base; 

 leaves 1-2-pinnate with long linear leaflets, the upper often more dissected : 

 involucels very small or none : fruit narrowly oblong, 4 lines long, narrowly 

 winged; 2 vittae on the commissure, broad and thin. — P. Utviijcilitin and P. 

 abrotaiii/oUum of Nutt. ; P.farinomin and P. tenuissimum of Geyer. Washington 

 Territory and Oregon to W. Montana; the root much used by the Indians. 

 There is one other imperfectly known allied acaulescent species in the same 

 region, and probably more. 



•*- +- Leaflets ovate, toothed or sometimes pinnatifid : fruit orbicular or ellipti- 

 cal : glabrous. 



7. P. EuRYPTERA, Gray. Low : leaves ternate ; leaflets broadly cordate, 

 coarsely toothed, an inch long or less: fruit 5 lines in diameter, emarginate at 

 each end, broadly winged ; 2 vittje on the commissure. — Proc. Am. Acad. 

 7. 848. Euri/plcra htcida, Nutt. ; Torrey, Bot. Mex. Bound, t. 27. 



8. P. PARViKOLiUM, Torr. & Gray. Low, slender: leaves deltoid in outline, 

 biternate, 2 inches long ; leaflets ovate, laciniatcly lobeil and toothed or i)innati- 



