200 



above, long acuminate, minutely rough above, slightly nodulose, 

 those of the fertile culms shorter that the culm, those of the 

 sterile culms much longer than the fertile culms. Lower sheaths 

 overlapping, loose, reddish below, ventral band white or tawny 

 hyaline, easily ruptured, mouth brown. Terminal 2-4 spikes 

 staminate, slender cylindric, sessile or nearly so, 1-5 cm. long, 

 whitish or brownish, scales acute, hyaline. Pistillate spikes 2-3, 

 cylindric, 1.5-6.5 cm. long, 7-10 mm. wide, the upper sessile or 

 nearly so, the lowest short or long peduncled, the lowest rather 

 loosely flowered, attenuate at base, all separated. Bracts of the 

 staminate spikes inconspicuous and almost scalelike to shorter 

 or (the lowest) longer than the spike. Bracts of the pistillate 

 spikes leaflike, shorter or longer than the inflorescence. Peri- 

 gynia brown, hairy, tough, somewhat inflated, faintly impressed 

 nerved or nerves hidden by the pubescence, sessile, 4.5-5 mm. 

 long, 2 mm. wide, slender ovoid with short bidentate beak, teeth 

 erect or spreading, about 3^2 m^n- long. Achene trigonous, 

 obovoid, 1.75-2 mm. long, 1-1.25 mm. wide, smooth, dull, light 

 brown; style uniform. Scales whitish hyaline or with brown 

 margin and green midrib, cuspidate, usually shorter than the 

 perigynia. Stigmas 3. Though the fertile culms are numerous, 

 few achenes develop so that the plants are almost sterile. 



The above description is based primarily on plants found 

 growing in open damp alluvial soil at one locality in Macon Co., 

 Illinois. My number 2338, preserved in my herbarium, is desig- 

 nated as the type. Duplicate specimens have been deposited in 

 a number of the consulting and private herbaria of the country. 

 At the type locality are found both parents, Carex impressa 

 (Wright) Mackenzie and Carex lanuginosa Michx., Carex 

 stricta Lam. var. angustata (Boott) Bailey, Carex lupuUna 

 Muhl. var. pedunculata Dewey, Carex lupuliformis Sartwell, 

 Carex crus-corvi Shuttlw., Carex stipata Muhl., Carex tribu- 

 loides Wahlenb.,. Carex tribuloides Wahlenb. var. turhata Bailey, 

 Carex granularis Muhl., and Carex muskingumensis Schwein. 



The following key will serve to separate this hybrid from the 

 parent species: 



Perigynia pubescent. 



Plants slender, leaves 2-5 mm. broad, heads less than 7 mm. thick, perigynia 

 abruptly contracted to the short beak. Carex lanuginosa Michx. 



Plants stout, leaves 4-7 mm. wide, heads 7-10 mm. thick, perigynia tapering 

 gradually to the longer beak, faintly impressed nerved, almost sterile. 



Carex impressaX C. lanuginosa. 



