L Y CO PODIA CE^. 1 3 5 



ft Branches few and irregular or wholly wanting. 

 \ Stems rough, tuber culate. 



9. E. robustum A. Br. Stems 3 n high, and some- 

 times nearly i' thick, 20 48 furrowed ; ridges roughened with 

 a single series of transversely-oblong, siliceous tubercles ; sheath 

 short, cylindric, marked with black girdles at the base, and at 

 the base of the caducous teeth ; ridges of the sheaths tricari- 

 nate. Ohio to Louisiana, California and northward. 



10. E. hiemale L. (SCOURING-RUSH.) Jstems i 4 high, 

 rough, 8 34 furrowed ; ridges with two indistinct lines of tu- 

 bercles ; sheaths rather long, cylindric, marked with one or two 

 black girdles ; ridges of the sheath obscurely quadricarinate ; 

 teeth membranous, soon deciduous. North America gener- 

 ally. 



\\ Stems not tuberculate. 



n. E. laevig-atum A. Br. Stems i 5 high, pale-green, 

 14 30 furrowed ; the ridges almost smooth ; sheaths elongate, 

 enlarged upward, marked with a black girdle at the base of the 

 mostly deciduous white margined teeth, and rarely also at the 

 base of the sheath ; ridges of the sheath with a central carina 

 and sometimes with faint, short, lateral ones. North Carolina 

 and Ohio to Louisiana, California and Oregon. 



** Stems slender, tufted, 5 \ogrooved. 



12. E. variegatum Schleich. Stems ascending, 6' 18' 

 long, usually simple from a branched base, 510 furrowed ; 

 sheaths green, variegated with black above, the teeth 5 10, 

 tipped with a deciduous bristle ; central air-cavity small. Bel- 

 lows Falls, New Hampshire (Carey}, Niagara Falls to Illinois 

 and northward to Greenland and Alaska. 



13. E. scirpoides Michx. Stems filiform, very numerous, 

 3 6' high, flexuous and curving, mostly 6-furrowed, with acute 

 ridges ; sheaths 3-toothed, the bristle tips more persistent ; cen- 

 tral air-cavity wanting. New England to Pennsylvania, Illinois 

 and northward. 



ORDER VI. LYCOPODIACE^E Lindl. 



Moss-like, terrestrial plants with small, lanceolate or subu- 

 late, sometimes oblong or roundish, simple leaves, arranged in 



