63 



rounder, Avith u fino but nbuiidiiut puboscciKC, proiuinont dorsal ribs, and 

 the numerous oil-tubes superficially distinct. In P. toinenioHuin not only 

 the oil-tubes but the dorsal ribs are completely hidden by the tomentum. 



i^ 3- Low and rather sl«nder, from elongated comparatively slender 

 roots: leaves rather small, more or less pinnately compound (the first 

 division sometimes ternate), with short segments: fruit-wings narrow 

 (never broader than body): oil-tubes :> to (i in the intervals (mostly solitary 

 in P. nndicaule). 



* Flowers white: fniit-zcinos more thai/ half as zvide as . 

 body. 



](). P. Nevadense WatsDU, Proc. Am. Acad. xi. 148. 

 Glaucous, puberulent, shortly caulescent, peduncles 8 to 15 inches 

 high: leaves pinnately decompound, with small segments: umbel 

 unequally 5 to 10-rayed, with involucels of scarious-margined 

 linear-lanceolate bractlets; rays often 1 to 2 inches long ; pedicels 

 -J to 5 lines long: fruit rounded to ovate, somewhat pubescent 

 (rarely glabrous), 8 to 5 lines long, 'i to 4 lines broad, with wings 

 almost as broad as body, and evident dorsal and intermediate ribs: 

 oil-tubes 8 or 4 in the intervals, 4 to I) on the commissural side. — 

 P. irudicaitle of Watson, King's Rep. v. 180, and others, not Nutt. 

 ERst of the Sierra Nevada, from N. California and S. E. Oregon 

 (HoweU) to Nevada and Utah. Fl. >.pril to June. 



17. P, nudicaule Nutl.Torr. iK: (ira\, Fl. i. ()27. Acaules- 

 cent or shortly caulescent, with peduncles 8 to <S inches high, pubes- 

 cent, from a thick elongated root (often swollen in places): leaves 

 bipinnate, the small oblong segments entire or toothed: umbel un- 

 equally T) to 8-rayed, with involucels of scarious-margined (often 

 purplish) lanceolate bractlets; rays ^ to li/< inches long; pedicels 

 2]4 to 8^2 l»'it-'s long; Hovvers white or pinkish: fruit almost round, 

 emarginate at base, glabrous, 2]4 lines long, 2 lines broad, with 

 v/ings not as broad as body, and indistinct or obsolete dorsal and 

 intermediate ribs: oil-tubes solitar\- in t!ie intervals (rarely 2 in 

 the lateral intervals), 4 on the commisMnal side: seed-face plane. 



(Fig. rri.) 



Arizona {I'dhner l,").s of l,s7<i, l.sl of Is77) and New MlxIlm) uurlhward Lo 

 the boundary, and extending eastward to Minnesota, Iowa and Kansas, 

 Fl. March to May. 



This is one of our earliest bloomers and in this regard, in its own range, 

 it represents the more eastern Erigeniu. This is the ('i/moitlcrun moitlnnus 

 Porter A- Coulter's Flora Colorado, Irom iilnins near Denver. 



