GREAT EQUISETUM. 
75 
perfect development. One character, however, must not be 
passed over in silence, and that is, the liability of the branches 
to emit two, three, four, or even five, secondary branches, from 
the summit of the second joint : these branches are usually 
slender, and when present they give the plant a beautifully com- 
pound and feathery appearance. Sir J. E. Smith describes the 
1 branches of this species as four-angled, each angle having a 
longitudinal furrow, and remarks that this structure was first 
noticed by Mr, J. D. Sowerby ; but the description given by 
Ehrhart and Roth, in the works previously quoted, appear to me 
more precise and accurate, and I think must also be of earlier 
date. Ehrhart describes the branches as suhquadragenis, octo- 
sulcatisj sulcis alternis majorihus^'^ and Roth uses these words— 
“ rami * octo-sulcati, sulcis altemiis profundiorihus^ 
hinc tetragonir Both the descriptions are admirably applicable 
to our British plant, and satisfactorily fix its identity. Although 
there is some trouble in finding out and deciphering every pre- 
vious description of a plant, yet an author should do this as far 
as he can, and the knowledge thus gained will amply repay him. 
It is my own misfortune to be unable to devote the time requi- 
site for such a delightful labour ; and I can seldom give the 
continental authors of the Linnean school the attentive perusal 
they deserve, except when a doubtful species or confused syno- 
nymy actually enforces the task : but the search on these occa- 
sions, limited though it be, never fails to exhibit new causes to 
admire the skill, patience, accuracy, and profound knowledge 
exhibited in their careful writings. 
The stem presents a transverse section very different from that 
of any other species : it is represented on the next page, at 
figure c. At figure d I have attempted to show the structure of 
the sheaths of the branches in this species. These sheaths of 
the branches, secondary sheaths, or vaginulcBj as they are termed 
by Roth and others, are so different in the British Equisetums, 
that the inspection of a single one is quite sufficient to- determine 
the species ; and when specimens have been selected without 
much care for a herbarium, it not unfrequently happens that no 
other diagnostic can be consulted. I iherefore invite attention 
to the descriptions which I have drawn up with considerable 
