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CLASS XXL— CRYPTOGAMIA. 
(FILICES.) 
385. EQUISETUM. Gen. pi. 1614. 
Floral receptacles peltate, many-angled, col- 
lected into a spike. Indusium corniculate. 
Stamina 4:. Style none. Seedi. — Mutt. 
arvcnse. 1 . E. barren stems simply branched: branches 
somewhat rough, four-angled ; fructification 
simple^ sheaths cylindrical, incised-deutate; 
teeth acute, — Willd. 
Icon. Schk. filic. t. 167. (Pursh.) 
Field Horse-tail. 
In wet fields near water courses; common. Perennial. 
May. 
syivaticum. 2 . E. barren and fruit-bearing stems doubly- 
branched ; branches roiighish, deflexed, four- 
angled ; branchlets sub-triquetrous. — Willd. 
enum- and Willd. 
Icon. Schk. filic. t. 166. FI. Dan. 1182. 
Wood Horse-tail. 
In sandy woods bordering* the Delaware, several miles be- 
low Kaighn’s point ; rare. Perennial. April. 
hyeraaie. 3 , E. stems simple^ erect, very rough, bearing 
spikes at the top; sheaths discoloured, base 
and apex sphacelate ; teeth aristated, entirely 
caducous.— Willd. 
Icon. Schk. filic. t. 172. 
Hough Horse-tail. Scouring Rush. Scour-grass. 
From two to three feet high. The cuticle of this species 
contains silex. Hence it is used in polishing pewter and 
