236 MAcKENZIE: NOTES ON CAREX 
Briefly stated, the European Carex riparia is a plant with closely 
bunched and very thick staminate spikes, the pistillate scales are 
large and very conspicuously purplish-margined, the fertile culms 
are phyllopodic, and the lower sheaths are neither fibrillose nor 
strongly purplish-tinged. On the other hand, the American Carex 
lacustris has scattered slender staminate spikes, the pistillate scales 
are smaller and the purplish margins generally noticeably less con- 
spicuous, the fertile culms are aphyllopodic, and the lower sheaths 
are strongly fibrillose and strongly purplish-tinged. 
Carex lacustris, as above defined, has a range from Maine and 
Vermont to Delaware, Minnesota, and Iowa. In the South and 
West, however, its place is taken by an allied but distinct plant of 
wide distribution. Although this last-mentioned plant has not in 
general been differentiated from Carex lacustris, yet many years 
ago it was published by S. Hart Wright as a variety of Carer 
riparia under the name Carex riparia var. impressa (Bull. Torrey 
Club g: 151. 1882). It has the scattered slender staminate 
spikes of Carex lacustris and its pistillate scales are even lighter- 
colored and with less of a purplish tinge. On the other hand it 
has the phyllopodic fertile culms not tinged with purplish or but 
little so and not fibrillose at the base, which are characters of the 
European Carex riparia. From both these species it differs also 
in the perigynia, which are impressed-nerved when young, but at 
maturity appear nerveless at a distance or on close inspection very 
finely impressed-nerved, in contradistinction to the strongly nerved 
perigynia of the other species above discussed. This plant doubt- 
less deserves specific rank, as the following detailed description 
will show: 
* Carex impressa (S. H. Wright) Mackenzie, comb. nov. 
Carex riparia impressa S, H. Wright, Bull. Torrey Club g: 151- 
1882. 
Culms stout, in dense clumps, 5-8 dm. high, phyllopodic, 
neither fibrillose nor purplish-tinged at base, stoloniferous, ex- 
ceeded by the leaves, smooth or more or less roughened on the 
angles above. Leaves with well-developed blades usually six to 
twelve to a fertile culm, mostly bunched towards the base, the 
blades 4—7 mm. wide, sometimes as much as 4 dm. long, flattened 
or folded at base, nodulose, stiff, varying from smooth on both 
