Equisetum . ] 
FERNS. 
77 
This plant differs from Equisetum arvense in its more glaucous green color 
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. 
II ab — F irst found by Mr. T. Drummond at Wolf Hill, the seat of W. 
Thompson, Esq., near Belfast. 
3.— EQUISETUM ARVENSE. 
CORN HORSE-TAIL. 
(Plate .9, 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., Huds., 
Light/., With., Pursh., Mack., Gray. — Equisetum segetale, Ger. 
Fig.— E. B. 2020 .—Bolt. 34 .—Flo. Lon.U.—Ger. Her. 1114.— Park. 1202. 
Des. — Root branched, creeping. Main stem of the barren frond 
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 fronds 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 channelled, 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 co- 
lored, 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 dia- 
phanous 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 com, 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 Hah. — 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. 
