EQUISETACEAE. 



VOL. I. 



9. Equisetum laevigatum A. Br. Smooth 

 Scouring-rush. Fig. 97. 



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

 Sci. 46 : 87. 1844. 



Stems i-5 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 rariegatum 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. 



