CYPERACEAE (SEDGE FAMILY) 



181 



18. E. acicularU. 



14. E. r/olfii. 



E. tortiliH. 



E. taherculoaa. 



17. E. Torreyana. 



18. 



E. melanocarpa. 



ft. Aclienes triangular or tnrgid ; style 3-cleft g. 

 g. Achenes regularly reticulate or cross-lined. 



Spikelets flattened, 3-y-flo%vered ; tlie thin scales 2-3-ranked 

 Spikelets terete ; the scales many-ranked. 



Upper sheaths loos«, with white scarious tips; achenes 

 finely cross-lined between the strong ribs .... 

 Upper sheaths close and firm, not scarious ; achenes* distinctly 

 reticulate. 

 Tubercle conic-subulate, much smaller than the achene 

 Tubercle cap-shajjcd, as large as the achene 

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

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



t. Achenes white 



4. _Achenes yellow, brown, or black j. 

 J. Achenes smooth. 



Tubercle flattened and closely covering the top of the 



black achene 



Tubercle short-conic, constricted below, narrower than 



the olive-brown achene 19. ^. albida 



J. Achenes papulose-roughened. 



Achene with prominent keel-like angles .... 



Achene with the angles not keeled. 



Tips of the upper sheaths dark -girdled ; achenes 



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 ; achenes whitish- 

 yellow, minutely roughened, with distinct angles 

 h. Tubercle long-conic, higher than broad. 



Tubercle clearly distinct from the achene. 

 Tubercle conic-subulate, much narrower than the plump 

 achene. 



Bristles exceeding the achene 



Bristles wanting (24) E.' intermedia 



Tubercle conic-deltoid, nearly as broad as the compressed 



achene . • • ^ 25. E. Macounii 



Tubercle seemingly confluent with the achene . . .26. E. roateUaia. 



20. E. tricostata. 



21. E. tenuis. 



22. E. acuminata. 



23. E. mtida. 



24. E. intermedia. 



Ilabereri, 



238. E. interstincta. 



1. E. interstincta (Vahl.) K. & S. Culms large and stout 

 (0.5-1 m. hi^lOi knotted as if j(Anted by many cross-partitions ; 

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

 in several ranks, pale, with scarious mar- 

 gins ; achene with transversely linear-rec- 

 ta7ignlar reticulation cind a conical-beaked 

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

 equisetoidas 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 

 ^-angled; spikelet 2-6 cm. long ; achene 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. Floirer-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, fe^v-ranked, convolute-clasping the long 

 flattened joints of the axis, lanceolate, with thin 

 scarious margins; achene oblong-obovate, tri- 

 angular, minutely reticulated, about half the 

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

 — Sliallow water, N. B. to Fla., w. to Mich, and Ind. Fig. 240. 

 4. E. ochreata (Nees) Steud. Similar in liabit 1o the next; 

 the capillary culms 3-30 cm. high ; spikelets 2-() mm. long ; scales 



239. E. quadrangulata. 



240. E. Kobbinsii. 



'241. E. ochreata 

 Spikelet X 2%. 

 Achene x 10. 



