292 Proceedings of the Ohio State Academy of Science. 



4. Eqiiisctiini fliiviatilc L. Swamp Horsetail. 



Stems all alike, annual, 1-4 feet high, branciied, the branches 

 hollow and slender. Rhizome hollow. In swamps and wet 

 places. Xot common but to be founrl in most parts of the state 

 in suitable habitats. 



5. Eqiiiscfiiiii lacrigatiuii A. Br. Smooth Scouring-rush. 



Stems annual or perennial, 1-5 feet high, simple or little 

 l^ranched, pale green ; sheaths funnel shaped. Stomata in regu- 

 lar rows ; ridges with broad transverse or diagonal, wart-like 

 protuberances. Cones pointed or without a point and merely 

 acute. In sandy soil and on clay banks. General but apparently 

 not common in Ohio. 



6. Eqiiisctuni varicgatum Schleich. A'ariegated Scouring-rush. 



Stems evergreen, slender, usually simple, 6-18 inches high. 

 Central cavity small, stems 5-10 furrowed, with stomata in regu- 

 lar rows. In sandy places. Lake county. (Erie Co., IMoseley 

 herbarium. ) 



7. Equisctiun hycnialc L. Common Scouring-rush. 



Stems slender and stiff, evergreen, 1-4 feet high, sometimes 

 branched, often with water or ice in the central cavity in winter; 

 ridges w'ith two indistinct lines of tubercles, ridges of the sheath 

 obscurely 4-carinate. Cones pointed. In wet places and on 

 l)anks, especially along streams. General in Ohio. 



8. Eqiiisetuni rohu'stv.m A. Br. Great Scouring-rush. 



Stems very stout, sometimes branched, evergreen, 2-8 feet 

 high, 20-48-furrowed. the ridges with a single series of siliceous 

 tubercles. Ridges of the sheath 3-carinate. Cones pointed. In 

 wet places and on l)anks. Apparently general in Ohio. 



Class III. LvcoPODiEAE. Lycopods. 155 species. 



Sporophyte perennial, herbaceous, with or without rhi- 

 zome, the aerial stems upright or trailing ; branching monopodia! 



