HORSETAILS 177 
the branches shorter. The stems, which are pale green, are at their thickest 
_ part of the size of a stout walking-stick, gradually tapering upwards, and 
becoming very slender at the top. Their smooth surface is delicately marked 
with from twenty to forty lines, which, running on into the sheaths, become 
there more distinct. The sheaths are about half an inch long, the lower part 
green, the upper encircled by a dark brown ring, and they fit the stem closely. 
The teeth are slender, dark brown with white edges, and often growing in 
twos or threes together. The branches have frequently at their second 
joints from two to five secondary branches; and their sheaths terminate in 
four or five teeth, each of which extends into a slender black bristle with 
two toothed ribs, a character which is very useful in determining the species. 
The fertile stems of this species are much shorter than the barren ones, 
rarely exceeding a foot in height. They are succulent, reddish-white, 
smooth, and unbranched, with large, loose, funnel-shaped sheaths, the lower 
ones smaller than the upper. These sheaths, which are pale green at the 
lower, and dark brown at the higher part, are distinctly marked with lines, 
and have from thirty to forty long slender teeth. The catkins are two or 
three inches long, and have an immense number of scales arranged in whorls 
around them, the lower scales forming distinct rings. 
This is not an uncommon though a somewhat local plant; and notwith- 
standing its name of Water Horsetail, it grows quite as often, or more so, on 
sandy or clayey moist soils, as on the borders of rivers or ponds, and in bogs, 
nor is it frequently, if ever, to be seen growing in the water. Its under- 
ground stem creeps far in the moist earth, where its black wiry roots increase 
rapidly, and are very abundant. 
When this Horsetail grows in large masses, as it sometimes does in the 
neighbourhood of London, a third kind of stem is occasionally to be found 
in August, smaller and shorter than the ordinary stem, its sheaths less 
spreading, and its cone smaller. This is a dwarfed form of the plant, owing 
to the spot on which it occurs being not sufficiently moist for its luxuriant 
growth. This is also known as EZ. maximum. 
8. Variegated Rough Horsetail (Z. variegdtum).—Stems trailing or 
erect; sheaths black at the top; teeth few, white, not falling off. This is 
one of the plants of the sea-shore, and one which, if it occurs in any quantity, 
proves valuable in binding down the loose sands. Its underground stem creeps 
for a long way just beneath the surface of the soil, and its root is formed 
of numerous whorls-of fibres. It sometimes grows inland, on the banks of 
lakes, rivers, and in ditches, and under such circumstances becomes more 
luxuriant than on the sea-sands. 
In this species the fertile and barren stems are alike; they are scarcely 
if at all branched, except at the base, but they have numerous branches just 
at the surface of the soil, or on the underground stem just below it. Occa- 
sionally the erect stems have a branch, very similar to the stem itself, arising 
from a joint here and there. The stems, which are about a foot high, are 
grooved, having from four to fourteen strong ridges. The sheaths, which 
are ribbed like the stems, are green below and black above, and their margins 
are fringed with black teeth of the same number as the ridges on the stem. 
These teeth have thin white edges and bristle-points. 
Iv.—23 
