EQUISETACEAE. 



VOL. I. 



9. Equisetum laevigatum A. Br. Smooth 

 Scouring-rush. Fig. 97. 



Eqnisetum laevigatum A. Br. ; Engelm. Amer. Journ. 

 Sci. 46: 87. 1844. 



Stems l-S high, simple or little branched, pale 

 green, annual or persistent, i4-3O-furrowed, the 

 ridges almost smooth. Sheaths elongated and en- 

 larged upward, marked with a black girdle at the 

 base of the mostly deciduous, white-margined teeth 

 and rarely also at their bases ; ridges of the sheath 

 with a faint central carina and sometimes with faint 

 short lateral ones ; stomata arranged in single series ; 

 central cavity very large, the wall of the stem very 

 thin, spikes pointed. 



Along streams and rivers, especially in clay _soil, 

 Ontario to New Jersey, North Carolina, Louisiana, 

 British Columbia and the Mexican border. May-June. 



10. Equisetum variegatum Schleich. 

 Variegated Equisetum. Fig. 98. 



Equisetum variegatum Schleich. Cat. PI. Helvet. 27. 



1807. 



Stems slender, perennial, evergreen, 6'-i8' long, 

 rough, usually simple from a branched base, com- 

 monly tufted, 5-io-furrowed, the stomata borne in 

 regular rows. Sheaths campanulate, distinctly 4-cari- 

 nate, green, variegated with black above, the median 

 furrow deep and excurrent to the teeth and down- 

 ward to the ridges of the stem, the teeth 5-10, each 

 tipped with a decidugus bristle ; central cavity small, 

 rarely wanting. 



Labrador and Greenland to Alaska, south to Con- 

 neticut, western New York, Nebraska and Nevada. 

 Also in Europe and Asia. Consists of several races. 

 May-June. 



ii. Equisetum scirpoides Michx. Sedge- 

 like Equisetum. Fig. 99. 



Equisetum scirpoides Michx. Fl. Bor. Am. 2: 281. 1803. 



Stems perennial, evergreen, very slender or filiform, 

 3'-6' long, somewhat rough, flexuous and curving, 

 growing in slender tufts, mostly 6-furrowed with acute 

 ridges, simple or branching from near the base. Sheaths 

 3-toothed, distinctly 4-carinate, the central furrow 

 broad, the lateral narrow, the bristly teeth rather per- 

 sistent; central cavity entirely wanting. 



On moist or wet wooded banks, Labrador to Alaska, 

 south to Pennsylvania, Illinois and British Columbia. 

 Also in Europe and Asia. May-June. 



Family 9. LYCOPODIACEAE Michx. Fl. Bor. Am. 2:281. 1803. 



CLUB-MOSS FAMILY. 



Somewhat moss-like, erect or trailing terrestrial herbs with numerous small 

 lanceolate or subulate simple leaves, sometimes oblong or roundish, arranged in 

 2-many ranks, the stems often elongated, usually freely branching. Sporanges 

 i-3-celled, solitary in the axils of the leaves or on their upper surfaces. Spores 

 uniform, minute. Prothallia (as far as known) mostly subterranean, with or 

 without chlorophyll, monoecious. 



