New Plants from Wyoming, XIII. 



By Aven Nelson 



J\ 



Potentilla Plattensis pedicellata 



Erect, slender, several-stemmed from the crown of a semi- 

 fleshy root, bright green but under a lens silky-strigose, taller 

 than the species (often 3 dm. high) : stipules entire or cleft- 

 toothed, ovate-lanceolate, acute : leaflets divided nearly to the 

 midrib, the segments linear-oblong, acute or subacute : inflores- 

 cence open, many-flowered, the long slender pedicels widely 

 divaricate : bractlets and sepals subequal : petals scarcely exceed- 

 ing the sepals. 



The aspect of the plants now proposed as a variety of P. " 

 Plattensis is so different from that of the species that I did not at 

 first associate them with it. Closer examination shows, however, 

 that they must be thus allied and probably best as a variety only. 



Collected on the grassy banks of a mountain stream, Cen- 

 tennial, Albany Co., July 27, 1900, no. 7730. 



y 



Ligusticum affine 



Moderately stout, .5—1 m. high, glabrous: root leaves large, 

 including the petiole from one third to one half the length of the 

 stems ; petiole from nearly as long to much exceeding the blade ; 

 blade usually biternate, then once or twice pinnate; segments 

 mostly ovate-oblong, deeply cleft into linear-oblong or linear- 

 lanceolate lobes, these sometimes few-toothed : stem leaves few 

 -3), much reduced, usually ternate, then pinnate, the segments 

 more deeply cleft or even divided and with narrower lobes : umbel 

 long-peduncled, sometimes 1-3 long-peduncled accessory umbels 

 (inflorescence subcorymbose), many-rayed, crowded (*. e. y the rays 

 suberect), with involucels of few linear-subulate bractlets which 

 are usually early deciduous : rays (fruiting) 3-6 cm. long : pedi- 

 cels 5-10 mm. long: flowers white : fruit elliptic, 5 mm. long, the 

 ribs distinctly winged : oil tubes usually 5 in the intervals and 10 

 on the commissural side : stylopodium flattened-hemispherical. 



This species now proposed was included in L. simulans C. & R. f 

 Monog. N. A. Umbel. 135, but it is no part of the type numbers 

 there cited. The species are distinct not only by good field char- 



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