4. 
Hox. 
Tubercle only slightly constricted from the 
achene; plants densely tufted annuals 
without long, firm rhizomes or stolons. 
5. Perianth bristles wanting or rarely as 
long as the achene; tubercle less than 
1/4 as high as achene. Expected 
(E. engelmanni). 
5. Perianth bristles longer than the achene 
and tubercle; tubercle 1/3 to 1/2 as 
Nachiras! aCheneres. cic cpeveve wisicloalelelle/ohorclelensiereheresrey Lie OD EUS al 
Tubercle deeply constricted from the achene; 
plants not densely tufted, with long, firm 
rhizomes or stolons. 
6. Basal scales of spikelet 2 or 3, the 
lowest not encircling the culm. Expected 
(E. palustris). 
6. Basal scale 1, encircling the culm. 
7. Spikelet closely many-flowered; scales 
broadly obtuse or rounded, opaque, 
appressed. Expected (E. calva). 
7. Spikelet loosely 5- to 30-flowered; 
scales acute or subobtuse, lustrous, 
loosely ascending... i...0<.6.sceee esses Be Halophila 
2. Achenes trigonous, styles 3-cleft. 
8. Achenes with shallow to deep honeycomb reticula- 
tion, or with prominent longitudinal ridges. 
Expected (E. acicularis, E. tortilis). 
8. Achenes smooth or minutely roughened. 
Qe 
Perianth bristles longer than the achene 
and tubercle; plant a tufted annual. (Also, 
mouth of sheath oblique; spikelets lanceolate; 
ACHEMS ESMOOIEN) "ajar ate ateriere atevereteietaile, etelle evetelel elevates eter autiis 
Perianth bristles shorter than the achene; 
plant perennial with long, slender rhizomes. 
(Also, culms flat, scales acuminate or 
attenuate). Expected (E. compressa). 
intermedia 
