﻿204 Nelson : New Plants from Wyoming 



compact, sub-spherical mass from two-thirds to more than a meter 

 in diameter : tap-root single, slender, brittle at maturity when the 

 plant becomes a " tumble-weed : fl leaves comparatively thin, vari- 

 able in shape, from broadly lanceolate to triangular, rarely sub- 

 hastate or broadly cuneate at base, sometimes irregularly dentate, 

 acute, obtuse or even toothed at apex, sessile or subsessile, 2-5 

 cm. long : pistillate flowers in axillary clusters : fruiting bracts 

 pedicelled, indurated, united only to the foliaceous margin, irreg- 

 ularly sub-orbicular, 7-14 mm. wide, free margins variously 

 toothed or lobed, the lobes of the opposing bracts not coinciding, 

 the upper lateral usually larger ; sides usually appendaged or 

 often only one side giving a triangular appearance to the fruit, ap- 

 pendages frequently somewhat foliaceous and conspicuous ; radicle 

 superior. (PI. 341.) 



The species is more nearly related to A. argentea Nutt. than 

 any other with which I am acquainted, and possibly has been con- 

 fused with it. It may be distinguished from A. argentea by its 

 habit and size and by its branching bracts. To confuse herbarium 

 specimens of the two would not be difficult, but specimens in the 

 field, never. 



So far as my observation goes it is very local. I have observed 

 it for several years past only in a large alkali basin on the Laramie 

 Plains. It is very abundant on the low flats adjacent to some al- 

 kali lakes. It grows rapidly, matures in September, and by Oc- 

 tober most of the plants are free and rolling. I have seen it wind- 

 rowed against the wire fences to more than the height of the fence, 

 so that the later comers tumbled over and passed on to lodge in 

 some ravine or against the next fence on the route. 



The accompanying half-tone plate shows a characteristic 

 specimen with a meter stick lying upon it, and is not unusual as 

 regards size. 



Type specimen in Herb. Univ. of Wyoming, no. 2796. 



LUPINUS HUMICOLA. 



Perrennial ; rootstock branched, the low crowns covered with 

 the scale-like dead petioles : stems several from each crown, sim- 

 ple, erect or ascending, 3-6 dm. high ; finely but not densely ap- 

 pressed-pubescent throughout: leaflets 7-12, usually 10 or II f 

 oblong-oblanceolate, cuspidate-acute, 4-7 cm. long : petioles slen- 

 der, elongated, radical 1.5-3 dm., cauline gradually shortened 

 upward : stipules linear-lanceolate, villous : racemes terminal, 



