142 PROCEEDINGS OP 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 : vittas distinct, solitary, 4 on tlie commissure. — Wash- 

 ington Territory and Idaho to the Sacramento. 



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

 tuse : fruit shorter and more ovate, very narrowly winged ; vittse obscure, 3 or 4 

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

 foliiim, Nutt. Oregon and N. Nevada/ 



t- -1- Leaves pinnate or bipinnate ; leaflets narrowly linear : involucels present. 



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

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

 evident; vittse about 2 in the intervals, 4 on the commissure. — Musenium tenui- 

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

 Colorado ; subalpine. 



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

 solitary, except in n. 8. 



•f- Leaflets linear, entire. 



4. P. TRiTERNATUM, Nutt. Finely puberulent, often tall : leaves biternate 

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

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



2 on the commissure. — P. leptocarpum, 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. triternatum, var. platycarpum, Torr. in 

 Stansb. Rep. 380. 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 vittse on the commissure, broad and thin. — P . Icevigatum and P. 

 abrotanifolium of Nutt. ; P.fan'no^um and P. tenuissimum of Geyer. Wasliington 

 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. ' 



•t- -1- Leaflets ovate, toothed or sometimes pinnatifid : fruit orbicular or eUipti- 

 cal : glabrous. 



7. P. EcRYPTERA, 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 vittae on the commissure. — Proc. Am. Acad. 

 7. 348. Earyptera Incida, Nutt. ; Torrey, Bot. Mex. Bound, t. 27. 



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

 biternate, 2 inches long ; leaflets ovate, laciniately lobed and toothed or pinnati- 



