CYPERACEAE. l6? 



Spikelets ^-ranked, flat, linear, falling away from the axis at maturity (?) many- 

 flowered. Scales 2-ranked, oarinate, conduplicate, decurrent on the ioint below. 

 Flowers perfect. Perianth of ^-9 retrorsely barbed bristles. Stamens 3. Style 

 2 -cleft at Uie summit, persistent as a beak on the summit of the achene. Achene 

 linear-oblong. [Name said to be from Dulcichimttrn^ a Latin name for some 

 sedge.] A monotypic genus of E. N. Amer. 



I. Dulichium arundinaceum (L.) Britton. DULICHIUM. (I. F. f. 576.) 

 Culm Ftout, 0.3-1 m. tall, erect. Leaves numerous, flat, 2-8 ~m. long, 4-8 mm. 

 wide, spreading or ascending, the lower sheaths bladeless, brown toward their sum- 

 mits; peduncles 4-25 mm. long; spikelets narrowly linear, spreading, 1-2.5 cm - 

 long, about 2 mm. wide, 6-i2-flowered; scales lanceolate, acuminate, strongly 

 several-nerved, appressed, brownish; bristles of the perianth rigid, longer thav ihe 

 achene; style long-exserted, persistent. In wet places, N. S. to Ont., Minn, and 

 Neb., south to Fla. and Tex. Aug.-Oct. [/}. spathaceum Pers.] 



4. ELEOCHARIS R. Br. (See Appendix.) 



Annual or perennial sedges. Culms simple, triangular, quadrangular, terete, 

 flattened or grooved, the leaves reduced to sheaths or the lowest very rarely blade- 

 bearing. Spikelets solitary, terminal, erect, several-many-flowered, not subtended 

 by an involucre. Scales concave, spirally imbricated all around. Perianths of 

 I 12 bristles, usually retrorsely barbed, wanting in some species. Stamens 23. 

 Style 2-cleft and achene lenticular or biconvex, or 3-cleft and achene 3-angled, but 

 sometimes with very obtuse angles and appearing turgid. Base of the style per- 

 sistent on the summit of the achene, forming a terminal tubercle. [Greek, refer- 

 ring to the growth of most of the species in marshy ground.] About 100 species, 

 widely distributed. Besides the following, some 17 others occur in the southern 

 and western parts of N. Am. 



Spikelet scarcely or not at all thicker than the culm. 

 Culm stout; spikelet many-flowered. 



Culm terete, nodose. i. E. interstincta. 



Culm quadrangular, continuous. 2. E. mutata. 



Culm slender, triangular, continuous ; spikelet few-flowered, subulate. 



3. E. Robbinsii. 

 Spikelet manifestly thicker than the culm. 



Style mostly z-cleft; achene lenticular or biconvex. 



Upper sheath scarious, hyaline ; plants perennial by slender rootstocks. 

 Scales pale green or nearly white; achene 0.5 mm. long. 



4. E. ochreata. 

 Scales dark reddish brown ; achene i mm. long. 5. E, olivacea. 



Upper sheath truncate, oblique, or toothed, not scarious. 

 Annual, with fibrous roots. 

 Achene jet black. 



Culms 2-8 cm. tall; achene 0.5 mm. long; bristles 2-4. 



6. E. afropurpurea, 

 Culms 7-25 cm. tall ; achene i mm. long; bristles 5-8. 



7. E. capitata. 

 Achene pale brown. 



Spikelet ovoid or oblong; tubercle deltoid, acute. 



8. E. ovata, 

 Spikelet oblong-cylindric ; tubercle broad, low. 



9. E. Engelmanni. 

 Perennial by horizontal rootstocks. 10. E. palustris. 



Style 3-cleft ; achene 3-angled or turgid. 

 Achene reticulated or cancellate. 



Spikelet compressed ; culm filiform. u. E. acicularis. 



Spikelet terete; culm slender. 



Achene transversely cancellate ; bristles none. 12. E. Wolfii, 

 Achene reticulated ; bristles present, stout. 



Tubercle conic, smaller than the achene. 13. E. tortilis. 



Tubercle cap-like, as large as the achene or larger. 



14. E. tuberculosa. 

 Achene smooth or papillose. 



Achene smooth, white; culms capillary. 15. E. Torreyana. 



Achene papillose or smooth, brown, black or yellow. 

 Tubercle depressed or short-conic. 



