26 22. Equisetum, 4. EQUISETACE/E. PI. end. cr. 
3. Equisetum arvense . Cornfield horsetail. 
m Barren stems simply branched, branches ronghish, four- 
sided; fruitful stems simple; sheaths cylindrical, distant, 
inciso-dentate ; teeth acute. 
E. arvense longioribus setis, Raii Syn. 130, 2; Park. 1202. 
E. segetale and E. sylvaticuin, Ger.em. 1114. 
Equisetum arvense, Lin. S. P . 1516. 
In moist cornfields and meadows; perennial; March 
and April. 
Barren stems , high, branched ip all parts; sheaths small; 
branches verticillate, spreading, angular; angles rather 
rough : Fertile stems earlier, 6 inches high ; sheaths very 
long ; spike lanceolate, long, large. 
elongatum. Branches very long. 
E. pratense, longissimis setis, Raii Syn. 131, 8. 
4. Equisetum fluviatile. River horsetail. 
Barren stems simply branched; branches rather rough, 
numerous, eightsided ; fruitful stems simple ; sheaths fun^ 
nelshape, rather close, lacero-dentate; teeth bearded. 
E. inajus, Raii Syn. 130, l ; Ger. em. 1113. 
E. majus palustre, Park. 1200. 
E. eburneum, Roth Germ. 111. 
E. fluviatile, Lin. S. P. 1517. 
Great horsetail. 
Marshes and river banks ; perennial ; April. 
Barren stem 5 or 6 feet high, upright, branched ; branches 
numerous, verticillate, long, usually simple, rough when 
viewed by a lens ; fruitful stems very simple ; sheaths short, 
brown, edge manyeut, bristly ; spike very large. 
5. Equisetum limosum. Mud horsetail . 
Stalk naked, branched ; branches about twelve, fivesided, 
smooth ; spike terminal. 
E. nudum laevius nostras, Raii Syn. 131, 10. 
E. fluviatile, FI. Dan. H84. 
E. limosum, Lin. S. P. 1517. 
Smooth naked horsetail. 
Marshes and watery places ; perennial; June and July. 
Stems two feet high, very smooth ; branches few, erect, 
smooth, very rarely verticillate ; spike large, brown, ovate ; 
barren stems very simple, narrow at top. 
$. ramosum. Stem branched. 
E. foliis nudum ramosum, Raii Syn, 132, 12. 
