80 
EQUISETACEiE. 
immature barren stem synehronous with the perfectly ripe fertile 
stem, both of them ascending from the samerhizoma ; and I may 
here remark that the appearance of the barren stem at this early 
period is very similar in E, sylvaticum, timbrosum, Telmateia 
and arvense, so that the figure referred to gives a good idea of 
them all. The fertile stem, selected for the figure as one of ave- 
rage size and proportions, may be thus described : it is about 
nine inches in length, and is divided into eight joints, which 
decrease in length from the catkin downwards : the stem is ex- 
tremely succulent, of a pale brown colour, smooth and quite 
without furrow^s : the sheaths are loose, somewhat gibbous and 
distinctly ribbed ; they are of a pale yellowish brown colour at 
the base, and have about ten dark brown, long, pointed, teeth : 
these occasionally adhere at the points in twos and threes. 
The catkin is an inch and a quarter in length, rather slender, 
blunt and rounded at the apex, and stands on a distinct foot- 
stalk, usually about equal to half its own length ; it is of a pale 
delicate brown colour, occasionally tinged with rosy red ; the 
scales are very variable in number, being sometimes scarcely a 
hundred, at others reaching two hundred and fifty. The catkin is 
mature in May, and sheds abundance of seed of a beautiful 
green colour. 
The following is a description of a barren stem. Length 
twenty-eight inches ; very slender at the summit, and increasing 
to the size of a goose-quill at the base : the colour is glaucous 
green towards the summit, and pale green towards the base : the 
stem has from ten to sixteen distinct but not very deep furrows, 
and the same number of equally distinct ribs, which are fur- 
nished with very minute siliceous points : the number of joints 
is twenty-one ; the length of the internodes varies from half an 
inch at the summit to two inches at the base : the sheaths, in- 
cluding the teeth, are scarcely more than a quarter of an inch 
in length ; they are but little larger than the stem, not however 
clasping it so tightly as in E.Jluviatile : they are furrowed in the 
same manner as the internodes, but the ribs are double : the 
teeth are ten to sixteen in number, wedge-shaped, acute, and 
dark brown or black ; they are commonly, but not constantly, 
furnished with a narrow^, brown, marginal membrane : 1 have 
