180 



CYPERACEAE (SEDGE FAMILY) 



strictly 1 -flowered ; upper scales ovate, pointed, rough on the keel ; stamens and 

 styles 2 ; leaves linear. — Low gi'ounds, Md. to O., 111., and southw. Aug. -Oct. 

 Fig. 236. 



3. DULICHIUM Pers. 



Spikelets linear, flattened, sessile in 2 ranks on peduncles 

 emerging from the sheaths of the leaves ; scales lanceolate, 

 decurrent, forming flat wing-like margins on the joint below. 

 Perianth of 6-9 downwardly barbed bristles. Stamens 3. 

 Style 2-cleft above. Achene flattened, linear-oblong, beaked 

 with the long persistent style. — A perennial herb, with a 

 terete simple hollow culm (2-10 dm. high), jointed and 

 leafy to the summit ; leaves short and flat, linear, 3-ranked. 

 (Name of uncertain origin.) 



1. D. arundinaceum (L.) Britton. (Z>. spathaceum 

 Pers.) — Wet swamps and borders of ponds, Nfd. to Wash., 



237. D. arundiDaceum. and SOUthw. July-Oct. FiG. 237. 



4. ELEOCHARIS R. Br. Spike Rush 



Spikelet few-many-flowered. Scales imbricated in many (rarely in 2 or 

 3) ranks. Perianth of 3-12 (commonly 6) bristles, usually rough or barbed 

 downward, rarely obsolete. Style 2-3-cleft, its bulbous base persistent as a 

 tubercle jointed u)3on the apex of" the lenticular or triangular achene. — Leafless 

 (rarely with basal capillary leaves), chiefly perennial, with tufted culms sheathed 

 at the base, from matted or creeping rootstocks ; flowering in summer. (Name 

 from eXos, a marsh, and x<ip'Ji grace ; being marsh plants. ) 



6. E. atropurpurea. 



a. Spikelet hardly if at all thicker than the spongy-cellular culm ; scales 

 firmly persistent. 

 Spikelet cylindric, many-flowered ; scales coriaceous, faintly nerved 

 or nerveless. 



Culm terete \. E. inter stincta. 



Culm sharply 4-angled 2. E. quadrangulata. 



Spikelet lineal-- or lance-awl-shaped, few-flowered; scales herba- 

 ceous, distincth' nerved 3. JS". Rohhinsii. 



a. Spikelet much thicker than the culm (or, if slender, with deciduous 

 scales) b. 

 h. Achenes lenticular or biconvex ; styles mostly 2-cleft c. 

 c. Upper sheaths loose, with white scarious tips. 



Scales white, with green midribs A. E. ochreata. 



Scales purple-brown, ^^ith green midribs b. E. olitiacea. 



c. Upper sheaths close and firm, green, not scarious, the tips often 



dark-margined d. 



d. Plants tufted, mostly annual, without conspicuous rootstocks e. 



e. Mature achenes black ; tubercle saucer-shaped : upper sheath 



oblique at tip, the elongate tooth narrow-deltoid. 



Spikelet 1.5-2 mm. thick ; achene 0.5 mm. long . 



Spikelet 2.5-3 ram. thick ; achene 1 mm. long. 



Scales whitish-brown, with greenish rib ; achenes jet 



black 1. E. capitata. 



Scales purple-brown ; achenes purple-black . . (7) E. capitata, v. dispar. 

 0. Mature achenes whitish to i)ale brown ; tubercle conic or 

 deltoid ; upper sheath with nearly truncate tip, the 

 short tooth broad-deltoid /. 

 /. Tubercle less than two-thirds as broad as the achene. 



Tubercle depressed turban-shape, broader than high ; 



bristles wanting or rudimentary .... 



Tubercle deltoid-conic, higher than broad ; bristles 

 much exceeding the achene ..... 



/. Tubercle nearly or quite as broad as the achene. 



Tubercle depressed-conic, concaved toward the tip, one- 

 third as high as the acliene ; bristles much exceeding 



the achene 10. E. oltusa. 



Tubercle tiat-deltoid. with straight sides, one-fourth as 

 hiffh as the achene ; bristles scarcely or not at all ex- 

 ceeilinjr the achene. 



Bri>tk-s about e(|iialing the achene . . .11. E. Engelmanni. 



Bristles r-.KliiiuMitarv or wanting . . (\\) E. Eimelmavni.x.detonfta. 

 d. Plants not tufted, perennial from elongate rootstocks . . 12. E. palustyia. 



8. E. diandra. 



9. E. ovata. 



