232 CRYPTOGAMIA. 
ORDER X. 
EQUISETACE#.—HORSE-TAILS. 
Included in the Filices of Linnzeus and Jussieu. 
Cuaracters.—Herbaceous perennial plants, with holl 
striated stems lined with silex under the cuticle, and a 
~ lated, each articulation being surrounded by a sheath, too 
or cleft longitudinally into a number of pieces. Often br. 
ed, the branches arising in whorls from the articulation. 
Fructification forming an oblong spike at the extremity 
the stem. Spike covered with peltate scales, from the under 
surface of which 4-7 wedge-shaped, one-valved thee, burst- — 
~ ing longitudinally, project inwards. The thece contain spo- 
rules, surrounded by minute granules, and having at thei 
base four elastic filaments, swelled at the apex or extremity, — 
twisted spirally round the sporule when moist, but unro 
and e: when dry. 
They may easily be distinguished by the tubular toothed 
_ sheath at each articulation of the stem, the terminal spike or 
cone of fructification, the four elastic filaments surrounding 
each sporule, and, if branched, by the branches being in 
__ whorls at the articulations, and sheathed like the stem. 
- Exampres.—This family consists of only one genus, Equi- 
 setum, or Horse-tail. E. arvense (Corn Horse-tail) is very 
common. E. fluviatile (Great Water Horse-tail) is frequent 
in muddy lakes, sides of rivers, and pools, and is the largest 
_ of the British species, being three or four feet high. E. syl- 
- paticum (Branched Wood Horse-tail) is an elegant species- 
r comers he Soe lent rai Sa 
