178 EQUISETACE—HORSETAILS 
The catkins are borne at the summit of some of these stems, and are 
small, black, and pointed, sometimes seated on the uppermost sheath, some- 
times elevated on a short footstalk ; they have very few scales. 
One variety of this plant is by some writers considered a distinct species, 
and is called #. arendrium. It is small, slender, and trailing, and the stem 
has about six furrows. The £. wilsini of some writers appears to be but 
another form of EF. variegdtum ; it is much stouter, taller, and more erect in 
habit, being sometimes three feet high. The stems are usually without 
branches, but are sometimes slightly branched. They have about ten ridges, 
but are not very rough. The sheaths, which are scarcely larger than the 
stem, are green, with a black rim at the margin. The teeth are short and 
blunt, black, and edged with white, and the cone is small, black, and pointed. 
The £. variegdtum is abundant on sand hills, on parts of the Cheshire 
coast, at Wardrew in Northumberland, and elsewhere. It is found chiefly 
in the north, and several localities in Scotland, Wales, and Ireland are 
recorded as places of its growth. 
9. Mackay’s Rough Horsetail, or Long-stemmed Horsetail 
(L. mackaii).—Stem simple, or very slightly branched, rough; sheaths 
close ; teeth slender, not falling off. This plant, which occurs in moist woods 
and mountain glens in Scotland, and in the north-east of Ireland, is a slender 
and almost unbranched species, the fertile and barren fronds being alike, save 
that the former bears a cone. The stems of the fronds arise from a branched 
rhizome, and are erect, and from two to four feet high. When they happen 
to be branched the branches are few, and are chiefly on the lower part of one 
or two of the side stems. The stem is deeply furrowed, having a double row 
of raised-points along the edges, and the furrows vary from eight to fourteen 
in number. The sheaths, which clasp the stems very closely, are, like them, 
marked with lines, and terminate with the same number of teeth. These 
are very narrow, awl-shaped, black, with thin white margins, ultimately 
entirely white. The black oblong catkin has a little point at the top, and its 
scales are about thirty in number. 
This plant was first discovered in 1833 by two botanists, Dr. Mackay and 
Mr. Whitla, in Colin Glen, near Belfast. It has since been found in the 
Den of Airly, in Forfarshire ; and on the banks of the Dee, in Aberdeen- 
shire ; as well as at Calton Glen, in Antrim; and Ballyharrigan Glen, 
Londonderry. It is the E. trachyodon of Braun, and is regarded by Sir 
J. D. Hooker as merely a variety of E. variegatum. 
THE END. 
