Equation.} EQUISETACEjE. 3 ^9 



peltate, polygonous scales, on the under side of which are from 

 4 — 7 involucres, which open longitudinally, and contain nu- 

 merous globose bodies, (capsule?) enfolded by four elastic 

 filaments, clavate at their extremities, (which some take for 

 stamens.) — Widely dispersed plants, growing in dry or in wet 

 places, sometimes aquatic. Stems rigid, leafless, jointed, striated, 

 the artictdations sheathed at the base ; the cuticle abounding in 

 silex ; branches, if any, mostly whorled, and as many will be 

 found as there are striae upon the stem and teeth to tlie sheath, if 

 the teeth do not continue more or less combined. 



1. Equisetum. Linn. Horse-tail. 



Character of the Genus the same as that of the Order.— Named 

 from Equus, a horse, and seta, a hair, or bristle ; meaning 

 horse-taU. 



* Fertile stems simple, succident, brownish, appearing before 

 the sterile ones and soon dying away, when the latter alone re- 

 mains through the summer, with whorled branches. 



1. E.fluviatile, Linn. Great Water Horse-tail. Sterile 

 steins with very numerous (about thirty) striae, and nearly erect 

 simple branches; stem cylindrical, smoothish ; sheaths with 

 close small subulate teeth ; fertile stems (short) without 

 branches, clothed with ample loose sheaths, having many sub- 

 ulate teeth. Br. Fl. ed. 3. p. 458. E. Bot. t. 2022. E. FL 

 v. iv. p. 337. 



Muddy lakes, sides of rivers and pools, frequent. Fl. April. — The 

 largest of all our species, its sterile stems or fronds being three to four 

 feet high. 



2. E. Drummondii, Hook. Blunt topped Horse-tail. Frond 

 very obtuse at the extremity ; sterile stem, especially upwards, 

 scabrous, with prominent points and about twenty striae ; teeth 

 of the sheath appressed ; branches simple, patent ; fertile stem 

 without branches, its sheaths approximate, appressed, with sub- 

 ulate teeth. Br. Fl. ed. 3. p. 459. Hooh. in E. Bot. Suppl. 

 t. 2777. 



First found by Mr. T. Drummond at Wolf-hill, the seat of William 

 Thompson, Esq. near Belfast, where I have collected specimens. Fl. 

 April.—" Allied to the following, but its colour is greener and less 

 glaucous, its stems rougher, with closely set, raised points, its angles 

 and branches much more numerous, and the whole barren-frond is 

 singularly blunt (in its outline) at the extremity, by which it may be 

 at once distinguished from E. arvense. The sheaths, though paler at 

 the base, have blacker and more prominent ribs upwards, and they are 

 so close as to imbricate each other ; their teeth also are more numerous 

 when they separate into the proper number." ( Hook. J 



3. E. arve?ise, Linn. Com Horse-tail. Frond attenuated 



