Subgenus Vignea (Lestib.) Kukenthal

 In Arkansas, seven sections represent the subgenus Vignea.  Section Divisae (represented by C. douglasii) and the possible addition Section Intermediae (C. sartwellii) are excluded from the Arkansas flora.  "Lenticular achenes, dorsiventrally flattened perigynia, two stigmas, and both carpellate and staminate flowers in each spike of the inflorescence" (Tucker 1987) characterize the subgenus.  In simpler terms, plants in this section have two sided fruits, usually flattened in most species, with two styles and stigmas.  Each spike has both male and female flowers.

Section Divisae (excluded from the Arkansas flora)

(revised June 18, 1999) 

Carex douglasii Boott 

Excluded from the flora of Arkansas (Smith 1988, Hyatt 1998).  Smith (1988) notes: "Reported for Newton County by Thompson (1977); it seems very unlikely for Arkansas, based on its distribution in Steyermark (1963)."  Smith's keys (Smith 1994) do not treat this taxon. It differs from all other known Arkansas carices by having this combination of characters: achenes two-sided, lenticular; styles and stigmas two; culms from long creeping rootstocks, mostly arising singly or a few together (modified from Steyermark).  [I need to find Thompson’s specimen to more formally exclude this taxon.] 

In Missouri, the plant occurs only along railroad track in St. Louis according to Steyermark (ibid) who says it "ranges from [St. Louis County] Missouri, Iowa, and Manitoba, west to British Columbia and south to Colorado and California" and "flowers early May to late June" in Missouri.