Nelson : New Plants from Wyoming 123 



-crusted with other salts, principally sodium sulphate. On these 

 white stretches this is often the only plant and as it reddens under 

 ' the September sun these patclies present a singularly beautiful ap- 

 pearance. 



Type specimen in Herb. University of Wyoming, no. 5284, 

 Laramie, September 6, 1898. 



Arabis exilis 



Biennial, possibly more enduring, 3-5 dm. hig\\ (including the 

 raceme) : taproot vertical or rarely curved at the summit ; stems 

 single, rarely 2 or more, mostly strict but occasionally branched 

 above, minutely stellate-pubescent, glabrate upward ; radjcal leaves 

 small, crowded on the crown, oblong, acute at both ends, 8-14 

 mm. long, petioles mostly shorter than the blade ; cauline some- 

 what crowded, the lower petiolcd, the upper sessile but not auricu- 

 late-clasping, minutely and closely stellate-pubescent as are the 

 radical leaves, broadly linear or lanceolate, acute, 1—4 cm. long : 

 raceme naked, glabrate, fully half the length of the plant, erect or 

 the summit slightly nodding : sepals broadly linear, green or 

 slightly tinged with purple, scarious-margincd, 3—4 mm. long, 

 pubescent as are the pedicels : petals white or purplish, linear- 

 spatulate, nearly twice the length of the calyx : pods 4-6 cm. 

 long, about 2 mm. wide, pendant on abruptly deflexed pedicels, 



5—8 mm. long : seeds in two rows, oval, about i mm. long. 



Its nearest ally seems to be A. pulchra Jones. Rather frequent 

 and abundant on sage-brush plains in the southern part of the 

 state. It seeks the rich, loose loam among the brush where it de- 

 velops early. 



Type specimen in Herb. University of Wyoming, no. 4523, 

 Evanston, June 4, 1898. 



Arabis lignifera 



Perennial from a branched, lignesccnt base surmounting a 

 woody taproot, 2—4 dm. high: annual stems usually several, erect 

 or decumbent at base, simple below, somewhat branched above, 

 from minutely stellate-pubescent to glabrous : leaves finely stel- 

 late-pubescent, entire, mostly basal, the conspicuous ones crowded 

 on one or more short barren branches from the lignescent base, 

 oblanceolatc, 3—5 cm. long, tapering into a slender petiole as long 

 or longer ; those on the woody caudex oblong-oblanceolate, i 

 ,20 mm. long, on slender petioles 2-3 times as long as the blade ; 

 cauline leaves, all but the lowest, short-auriculate, acute, narrowly 



