CYPERACEAE (SEDGE FAMILY) 



181 



K Aehenes triangular or turgid ; style 3-cleft g. 

 g. Aehenes regularly reticulate or cross-lined. 



Spikelets flattened, 8-9-fl(i\vered ; the thin scales 2-8-ranked . 18. E. acicalaria. 

 Spikelets terete ; the scales many-ranked. 



Upper sheaths loose, with white scnrious tips ; aehenes 



finely cross-lined between the strong ribs . . . . lA. E. WolJU. 

 Upper Bheaths close and firm, not scarious ; aehenes distinctly 

 reticulate. 

 Tubercle conic- subulate, much smaller than the aehene 15. E. ioriiUa, 



Tubercle cap-shaped, as large as the aehene . . .16. E. iuberculoaa. 



g. Aehenes smooth or papillose, not regularly reticulate h, 

 h. Tubercle depressed, as broad as high or broader. 



i. Aehenes white VI. E. Torreyana. 



i. Aehenes yellow, brown, or black j. 

 j, Aehenes smooth. 



Tubercle flattened and clofiely covering the top of the 



black aehene 



Tubercle short-conic, constricted below, narrower than 



the olive-brown aehene 



^. Aehenes papillose-roughened. 



Aehene with prominent keel-like angles . 

 Aehene with the angles not keeled. 

 Tips of the upper sheaths dark -girdled ; aehenes 

 golden-yellow or orange-brown (in age drab), 

 conspicuously papillose-roughened, plump, with 

 rounded angles. 



Culms filiform, 4-angled 



Culms flattened 



Tips of the upper sheaths whitish ; aehenes whitish- 

 yellow, minutely roughened, with distinct angles 28. E. TdUda. 

 A. Tubercle long-conic, higher than broad. 



Tubercle clearly distinct from the aehene. 

 Tubercle conic- subulate, much narrower than the plump 

 aehene. 



BHstles exceeding the aehene 



Bristles wanting (24) E. 



Tubercle conic-deltoid, nearly as broad as the compressed 



aehene 25. X Macounii. 



Tubercle seemingly confluent with the aehene . . .26. E. rostellata. 



18. E. melmiocarpa, 



19. E. alhida. 



20. E, tricostata. 



21. E. 



22. E, acuminata. 



24. E. intermedia, 

 intermedia, v. Habereri, 



288. E. interstineta. 



1. E. interstineta (Vahl.) R. & S. Culms large and stout 

 (0.5-1 m. high), knotted as if jointed by many cross-partitions ; 

 basal sheaths often leaf-bearing ; spikelets 2-4 cm. long ; scales 

 in several ranks, pale, with scarious mar- 

 gins ; aehene with transversely linear-rec- 

 tangular reticulation and a conical-beaked 

 tubercle ; bristles 6, rigid, or wanting. {E. 

 equisetoides Torr.) — Shallow water, Mass. 

 to Fla., w. to Mich, and Tex. (W. I., 

 S. A.) Fig. 238. 



2. E. quadrangulata (Michx.) R. & S. 

 Similar ; culm continuous and sharply 

 4-angled; spikelet 2-6 cm. long ; aehene finely reticulated, 

 with a conical flattened distinct tubercle. {E. mutata 

 Britton, not R. & S.) — Shallow water, Ct. to Mich., and 

 south w., rare. Fig. 239. 



3. E. Robbinsii Oakes. Flower-bearing 

 culms exactly triangular, rather slender, 



erect (2-7 dm. high), also producing tufts of capillary abortive 

 stems or fine leaves, which float in the water ; sheath obliquely 

 truncate ; spikelet 1-2.5 mm. long ; scales only 

 3-9, few-ranked, convolute-clasping the long 

 flattened joints of the axis, lanceolate, loith thin 

 scarious margins; aehene oblong-obovate, tri- 

 angular, minutely reticulated, about half the 

 length of the bristles, tipped with a flattened awl-shaped tubercle. 

 — Shallow water, N. B. to Fla., V7. to Mich, and Ind. Fig. 240. 

 4. E. ochreslta (Nees) Steud. Similar in habit to the next; 

 the capillary culms 3-30 cm. high j spikelets 2-6 mm. long ; scales 



19. E. quadrangulata. 



240. E. Robbinsii. 



241. E. ochreata. 

 Spikelet X 22/3- 

 Aehene x 10. 



