180 



CYPERACEAE (SEDGE FAMILY) 



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

 styles 2 ; leaves linear. —-low grounds, Ivld. to ()., 111., and south w. 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. arundinaceum. and SOUthw. July-Uct. FiG. 237. 





4. ELEOCHARIS K. Br. Spike Rush 



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

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

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

 tubercle jointed upon 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 marshy and x^^P'-^') grace; being marsh plants.) 



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

 firmly persistent. 

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

 or nerveless. 



Culm terete . . 



Culm sharply 4-angled . 



Spikeleli linear- or lance-awl-shaped, few-flowered ; scales herba- 

 ceous, distinctly nerved 



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



scales) b. 

 b. Achenes lenticular or biconvex ; styles mostly 2-cleft e. 

 c. Upper sheaths loose, with white scarious tips. 



Scales white, with preen midribs 



Scales purple-brown, with green midribs 



o. Upper sheaths close and Jirm, 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 mm. thick ; achene 1 mm. long. 

 Scales whitish-brown, with greenish rib ; achenes jet 



black 



Scales purple-brown ; achenes purple-black . . (7 

 e. Mature achenes whitish to pale 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 w^anting or rudimentary .... 

 Tubercle deltoid-conic, higher than broad ; bristles 



much exceeding the achene 



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



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

 third as high as the achene ; bristles much exceeding 



the achene 



Tubercle flat-deltoid, ^vith straight sides, one-fourth as 

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

 ceeding the achene. 

 Bristles about equaling the acheno 

 Bristles rudimentary or wanting . . (11) E. 

 dJ. Plants not tufted, perennial from elongate rootstocks . 



1. E. inter siincta. 



2. E. quadrangulata. 



E. EohMnsii. 



4. E. ochreata. 



5. E. olivaeea. 



E. atropurpurea. 



7. E. capitata. 

 ) E. capitata, v. dispa/r. 



B. E. diandra. 

 9. E. ovata. 



10. E. obtusa. 



11. E. Engelmawni. 

 EngelTnanni, v. detonsck 



12. E. palusiris. 



