Equisetum .] 
FERNS. 
77 
This plant differs from Equisetum arvense in its more glaucous green colour, 
very much more delicate habit both of stem and branches, and blunter outline. 
The fertile frond is much more rigid in texture, with harder, whiter, and more 
numerously-toothed sheaths, and the points of the teeth are more diaphanous 
than in the next species. 
11a b. — First found by Mr. T. Drummond at Wolf Hill, the seat of W. 
Thompson, Esq., near Belfast. 
3.— EQUISETUM ARVENSE. 
CORN HORSE-TAIL. 
(Plate IX, fig. 3.) 
Cha. — Barren stem taper-pointed, decumbent. Sheaths of the 
fertile stem three or four, distant, loose. 
Syn. — Equisetum arvense, Linn., Willd., Smith, Hook., Bolt., Ehrh., Huchs., 
Lightf., With., Pursh, Mack., Gray. — Equisetum segetale, Ger. 
Fig. — E. B. 2020. — Bolt. 34. — Flo. Lon. 04. — Ger. Her. 1114. — Park. 1202. 
Des. — Root branched, creeping. Main stem of the barren fi-ond 
procumbent, tapering to the end, sometimes very long, pointed, 
rough, with whorls of branches all the way down, and forked at the 
base; that is to say, two or more frouds springing from the same 
part of the root. Branches simple, varying much in number, fourteen 
or sixteen, if all are present, but generally not more than eight or 
ten, or even six, at the upper part of the frond. They are dark green, 
rough, four channeled, with simple angles. Fertile fronds appearing 
before the others, light brown, with four or five distant, deeply- 
toothed sheaths. The teeth are sharp, ribbed, and rather dark 
coloured, particularly round their edges. As the fertile frond comes 
to maturity, the sheaths decay from the point downwards ; thus 
their black tooth is often tipped with white, and surrounded with a 
diaphanous membrane, particularly the upper sheaths, which are 
larger and longer than those below. 
The plant puts on very different characters in different circumstances ; some- 
times it appears as a cylindrical pointed stem, without any branches ; this is its 
early state, for it does not throw out branches immediately, as in Equisetum 
fluviatile, therefore it never appears with a densely leafy, obtuse frond as that does. 
On strong soil, and in shady situations, as when hid among growing corn, the 
branches become exceedingly long, scattered in habit, and often geniculated, in 
which state it is represented by Gerard as Equisetum segetale. The closeness 
and number of the sheaths of the fertile stem are by no means a sure diagnostic 
of any of our species ; the remarks respecting them, therefore, are more general 
than specific information. 
Sit. and Hab. — In corn fields, sandy banks, waste ground, &c. This species 
is so common, and so difficult to eradicate, as to be a very troublesome weed. 
Geo. — Found equally in Europe, Asia, and North America. 
