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Nelson : New Plants fro:m Wyoming 351 



which it is clearly separated by i. Habitat: A. Hookcri iorms, 

 broad ccspitosc tufts on open ground, mostly on naked, clay, saline' 

 soils, as I have observed it throughout the breadth of Wyoming ; 

 this forms single, compact clumps in the shaded woods, growing 

 in the pine and spruce needles : 2. Characters : A. piuctonnn is 



F 



larger than the other in every way ; the branches of the caudex 

 longer, the leaves longer and more slenderly pungent, exceeding 

 (even twice as long as) the internodes, while in A, Hookcriih^ leaves 

 are shorter than the internodes. 



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While it resembles A. Hookcri in its inflorescence, yet the cyme 

 is more open, the flowers arc larger and the petals distinctly exceed 

 the sepals. As seen in the field they can never be confused, the 

 bushy clumps of this and the cespitose mats of A. Hookeri being 

 markedly distinct. Type specimen in Herb. University of Wy- 

 oming, no. 1595, Laramie Peak, Aug, 7, 1895. It has been dis- 

 tributed under the above number as A, Hookcri. 



Cheiranthus aridus 



Biennial, possibly more enduring, bushy branched, usually 

 many stemmed from the crown of the vertical taproot, sometimes 

 with an excurrent stem with se\'eral divaricate branches, mostly 

 low, rarely 3 dm. high : leaves oblanceolate, acute, entire or nearly 

 so, 4-8 cm. long, green in appearance but rather closely pubes- 

 cent with small, 2-partcd apprcssed hairs :' sepals narrowly ob- 

 long ; corolla large; the petals 16-20 mm. long, blade narrowly 

 obovate or broadly spatulate, shorter than the slender claw : com- 

 mencing to flower when small and fruiting copiously ; pods long 

 -12 cm.), sub-terete or elliptic in cross-section, not taper-pointed 

 but abruptly contracted into a short style; valves distinctly i- 

 ncrved. 



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Since the publication of Dr. Greene's paper on ChcirantJins 

 (Pittonia, 3 : 128) any one who has tried to arrange a considerable 

 amount of material in this genus according to the specific limits 

 there proposed has not only found it feasible, but has found the 

 disposition of material in this group much simplified. It was to 

 be expected that the breaking up of the aggregate, Erysimum as- 

 pcruui, into its species would disclose forms that now cannot be 

 united with any of those species, though they might have found 

 oblivion among the miscellany of the old E. aspcrian. Such is 



the species now proposed 



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