292 Proceedings of the Ohio State Academy of Science. 



4. Equisetum fiuvidtile L. Swamp Horsetail. 



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

 hollow and slender. Rhizome hollow. In swamps and wet 

 places. Not common but to be found in most parts of the state 

 in suitable habitats. 



5. Equisetum laevigdtum A. Br. Smooth Scouring- rush. 



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

 branched, 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. Equisetum variegdtum Schleich. Variegated 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., Moseley 

 herbarium. ) 



7. Equisetum hyemale 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 with two indistinct lines of tubercles, ridges of the sheath 

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

 banks, especially along streams. General in Ohio. 



8. Equisetum robu'stum 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 banks. Apparently general in Ohio. 



Class III. Lycopodieae. Lycopods. 155 species. 



Sporophyte perennial, herbaceous, with or without rhi- 

 zome, the aerial stems upright or trailing; branching monopodial 



