CXIII. EQUISETACEvE. 
599 
EquisetumJ] 
involucres, which open longitudinally and contain numerous 
globose bodies enfolded by 4 filaments clavate at their extre- 
mities. 
1. Equisetum Linn. Horse-tail. (Tab. XII. f. 4.) 
Character of the Genus the same as that of the Order. — 
Named from equus, a horse, and seta, a hair, or bristle ; whence 
the English name horse-tail. 
* Fertile stems unbranched *, succulent, appearing before the barren ones, 
which have whorled branches. 
1. E. Telmateia Ehrh. ( great-water II.) ; barren stems nearly 
smooth with very numerous (about 30) striae and nearly erect 
simple branches, sheaths of the branches with 4 close small subu- 
late 2-ribbed teeth, fertile stems (short) clothed with ample 
loose sheaths. Newm. p. 67, 76. E. fluviatile Sm. : E. B. 
t. 2022. 
Wet damp ground, sides of ditches, clay banks, and swampy bogs, 
frequent. y. 4. — The largest of all our species, its barren stems 
or fronds being 3 — 4 feet high. 
2. E. umbrosum Willd. ( blunt-topped H.) ; sterile frond very 
obtuse at the extremity its stem especially upwards scabrous 
with prominent points and about 20 strias, branches simple 
slender patent, the teeth of the sheaths 3 — 4 short acute with 
one rib disappearing before the apex, fertile stem with approxi- 
mate sheaths. Newm. p. 63. E. Drummondii Hoolt. : E. B. S. 
t. 2777. 
Wet places, rare. Mere Clough, near Manchester ; Yorkshire ; 
Northumberland ; Westmoreland. Aberdeenshire; near Forfar, and 
banks of the Isla and Esk, in Forfarshire, extending up the val- 
leys to their sources; by the Caledonian Canal; Falls of Moness; 
Ochills; Campsie Glen; Bonnington woods, Lanarkshire; Wood- 
cock Dale, Linlithgowshire. Near Belfast. y. 4. — Allied 
to the following species. 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 sin- 
gularly blunt (in its outline) at the extremity. In general ap- 
pearance the barren plant resembles E. sylvaticum, from which it is 
at once distinguished by the simple, not compound branches. Mr. 
Bentham considers this to be E. pratense Ehrh., but that species is 
said by Ehrhart to differ from E. arvense by the fertile stem being 
branched ; and if the same as E. umbrosum it must be in an abnormal 
condition, but most probably it belongs to a species of the next sec- 
tion; it was quite unknown to Willdenow except by description. 
1 In most of the species of this section the fertile stems occasionally produce 
whorled branches, the catkins and branches appearing at the same time : so that 
l this sectional character must not be taken in an absolute sense, but will indicate 
ihe usual or normal condition of the fronds. 
