EQUISETUM. 
257 
initiated an inch or two above the upper sheath, by cone¬ 
like heads, rather more than an inch long, tapering some¬ 
what above and below, and terminating in a blunt point. 
The peltate thecse-bearing scales, which are very nume¬ 
rous, often exceeding a couple of hundred, are arranged in 
whorls around the axis of the cone, as is the case generally 
in this family. At a right angle with their margin are 
ranged the spore-cases, four to seven in number ; they are 
oblong, membranous, parallel, white cells, bursting finally 
into two longitudinal valves, and discharging an abund¬ 
ance of very minute globular spores, of a beautiful blue- 
green colour. 
The barren stems are either erect or decumbent, and 
from one to two feet or more in height; they are often 
branched from the bottom to the top, but sometimes only 
the central and upper parts are branched. They spring 
up after the fertile stems have withered, and are of a 
pale-green colour; at first crowded with short appressed 
branches, which, by degrees, become elongated, and assume 
a spreading or somewhat drooping position, sometimes 
becoming again branched. The main stem has from ten 
to sixteen distinct shallow furrows, with corresponding 
ridges, and is, as well as the branches, studded over with 
s 
