CORN-FIELD EQUISETUM. 
79 
plants widely differ from the early disappearing plant described 
by Mr. Robinson in the passage above cited. 
The figures of this very common plant are so different that it 
seems impossible to reconcile the discrepancy otherwise than by 
a reference to the protean character of the original : that in 
Curtis's ‘ Flora Londinensis ’ * may perhaps be cited as the best. 
The corn-field Equisetum is supposed to be very injurious to 
cattle ; it is, however, most probable that they will not touch 
it, unless compelled by extreme hunger. 
This seems to be the only British species in which the fertile 
and barren stems are perfectly and constantly distinct, and of a 
different structure, the former having generally completely va- 
nished long before the latter have acquired their full development. 
In those species which are normally simple, ^. e. without whorls 
of branches, it appears the character of each full-sized and vigo- 
rous stem to produce a terminal cathin, consequently there is 
no observable difference in the structure of the fertile and bar- 
ren stems : in the following species, E. palustre and E. Jliivi- 
atile^ the same general character obtains, the grand distinction 
being in the almost constant presence of whorls of branches : 
in E. sylvaticum a marked difference is observable, for not only 
are a portion of the stems exclusively fertile and rapidly evanes- 
cent, but the mixed stems — those which bear both catkin and 
branches — are decidedly different to the exclusively barren ones, 
being more succulent, and having larger and looser sheaths : in 
E. umbrosum the discrepancy between fertile and barren stems 
is so great that the combination of the two, although common, 
has not been noticed by our British authors : in E. Telmateia 
these mixed stems are comparatively rare exceptions, and have 
almost been regarded as unnatural or monstrous ; so that we ar- 
rive, by an almost imperceptible transition, at E. arvense, in 
which the two kinds of stem are perfectly and constantly 
distinct. 
The figure at page 77 represents two stems of the corn-field 
Equisetum, of the natural size, a a being the fertile, h h the bar- 
ren stem : they are drawn from living specimens, and show the 
^ Curtis, Flov Loncl. pi. 285. 
