GREAT EQUrSETUM. 
73 
When the stem bears both fructification and branches, it is 
seldom in perfection until the month of August : such stems are 
far less numerous than in either of the preceding species, and 
bear but a small proportion to those which are exclusively fer- 
tile or exclusively barren : the catkin is much smaller than under 
ordinary circumstances : the stem also is smaller, although 
having longer joints ; the sheaths are shorter, less spreading, and 
of a pale green colour; the branches are placed on the second 
to the ninth or tenth joint, counting from the catkin ; in all the 
specimens I have seen they are ascending. Several botanists 
attribute this state of the plant to drought, and Mr. Francis 
observes that it may be produced at any time with such culti- 
vated plants as grow in pots, merely by removing the pots from 
the watery situations in which they are usually placed into a 
drier spot of ground. Mr. W. Wilson ” he continues, “ attri- 
butes this state of the plant to drought, as here stated, and adds 
that he has seen a specimen, gathered near Bangor, where this 
catkin was topped by a prolongation of the branched frond.”* 
The barren stem is much larger than in any other species of 
Equisetum with which I am acquainted : it occasionally attains 
a height of seven feet, and a circumference of more than two 
inches ; its outline and proportions are shown, on a very reduced 
scale, at page 76, fig. a, and one of the internodes, with its ac- 
companying sheaths, is represented of the natural size at fig. h. 
The following is the description of a living stem now before 
me, and of the average size. The entire length above ground, 
and including the ascending branches, is fifty-four inches ; the 
circumference, at twelve inches from the ground, is an inch and 
a half, but decreases upwards until it becomes extremely slen- 
der, terminating almost in a point. The surface of the stem is 
perfectly without ridges or furrows : the number of joints is 
forty : the colour of the internodes is white, with the slightest 
tinge of green, but those on the lower part of the stem often 
change to intense black : the black makes its first appearance in 
spots or blotches, giving the stem a singularly variegated ap- 
pearance ; but it rapidly spreads, and finally entirely occupies all 
* Analysis, p. 7(3. 
