﻿North American Polygonaceae. 41 



In dry soil on the Black Hills, South Dakota. Summer. 

 A species with the general habit of Eriogonum pauciflorun 



more delicate in all its parts. The leaves are more numerous than 

 they are in its relative and the blades of a thinner texture, but the 

 chief diagnostic character lies in the involucres ; these organs are 

 tubular or tubular-turbinate and twice as high as broad as com- 

 pared with thecampanulate involucres of E.pauciflorum, which are 



about as broad as high. 



The original specimens were collected by Mr. Rydberg at 

 Hermosa, in the Black Hills, South Dakota, June 23, 1892. Num- 

 ber 970. Altitude about 1,100 meters. 



' Eriogonum tenue. 



Perennial from a shubby base, slender, thinly tomentose to the 

 flowers. Stems loosely branching, 5-IO cm. long : leaves crowded 

 at the ends of the branches, linear or nearly so, 1-2 cm. long, ob- 

 tuse or acutish, revolute, thinly tomentose, but less densely so 

 above than beneath : scapes erect, simple, 5-10 cm. tall, furnished 

 with a whorl of leaf- like bracts above the middle : involucres soli- 

 tary tubes ; turbinate ; segments linear to linear-oblanceolate, 

 obtuse, shorter than the tubes, spreading or reflexed : calices gla- 

 brous, pale yellow, 5-6 mm. long, narrowed into stipe-like bases; 

 segments unequal, the 3 outer oblong-obovate, notched at the 



apex, the 3 inner spatulate, erose at the apex : filaments villous at 

 the base: achenes 3-angIed, villous above the middle. 



In dry sterile rocky situations on the Columbia River, Wash- 

 ington. Spring and summer. 



A species of slender habit, near Eriogonum spliacroceplialum, 

 but distinguishable by the narrow, linear, strongly revolute leaves 

 and the glabrous calices. 



The original specimens were collected by Mr. Suksdort, on 

 the Columbia River, in West Klickitat Cou«ty, Washington, May 

 15,1884. Number 694. 



Ekiogonum Porteri. 



A 



Stems branched below ; branches more or less densely tufted, 

 sometimes gnarled : leaves firm ; blades suborbicular or rhom- 

 boidal, 2-10 mm. long, obtuse or rounded at the apex ; petioles as 

 long as the blades or longer: scapes erect or ascending, 1-10 cm. 

 long, simple: involucres glabrous; tube 2 mm. high, constricted 



