of Horsetail, a not inapt comparison M'itli the barren fronds
of some of the species.
E q u ise tum a r y e n s e , Linnaius.— The Corn-field Horsetail.
This is the most common of the species, and in many
places is an injurious weed, very difficult to eradicate. It
occurs, here and there, almost everywhere in fields and
waste places, especially where the soil is inclined to be
sandy, and more abundant in moist than in dry places.
It has long, creeping, underground stems, which are a good
deal branched, and are cylindrical and jointed in the same
way as the stems which rise above ground. At the joints
they throw out whorls of tough, branching, fibrous roots.
The aerial stems are of two kinds, the one simple and
bearing the fructification only, the other branched and perfectly
barren.
The fertile stems are quite without branches, and grow
up early in spring, arriving at maturity and perishing long
before the barren ones have completed their growth. They
reach maturity in April and May. The stems vary, according
to the locality where they grow, from three to eight
or ten inches in height. They are hollow, succulent when
fresh, and of a light brown colour, nearly smooth, and apparently
without the siliceous coating common to the stems
of this race of plants. They are divided at intervals into
joints of variable length, the number of joints being also
variable, from six on stems of about four inches in length,
to eight on those which measure eight inches, though sometimes
specimens of equal length have but five or six joints.
Erom this cause they are much more distant on some stems
than on others; a space measuring three-quarters of an
inch being sometimes interposed betw'een the top of one
sheath and the base of the next above it. On the other
hand, they are sometimes so close as nearly to touch; but
we have seen no instance in which the base of a sheath is
covered by the sheath below it, except at the very lowest
part of the stem, where they become much reduced in size,
and are sometimes crowded. I t is usual for each succeeding
joint upwards to be somewhat more distant than the one
beneath it. The sheaths are large and loose, widening upwards
; they are pale-coloured, somewhat yellowish at the
base, and are divided above into about ten dark brown teeth,
which often adhere together in twos and threes. The teeth
are very narrowly lance-shaped and sharp-pointed, and are
the terminations of the ribs, about ten in number, by w’hich
the sheaths are marked.
These stems are terminated by cone-like heads, bearing