729 



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 Lon- 

 dinensis ' * may perhaps be cited as the best. 



The corn-field Equisetum is supposed to be very injurious to cat- 

 tle ; 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 vanished long be- 

 fore the latter have acquired their full development. In those species 

 which are constantly simple, i. e., without whorls of branches, it ap- 

 pears the character of each stem to produce a terminal catkin, conse- 

 quently, there is no observable difference in the structure of the fertile 

 and barren stems : in the following species, E. palustre and E. fluvi- 

 atile, the same general character obtains, the grand distinction being 

 in the almost constant presence of whorls of branches: in E. sylvati- 

 cum a marked difference is observable, for not only are a portion of 

 the stems exclusively fertile and rapidly evanescent, 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 au- 

 thors : in E. Telmateia these mixed stems are comparatively rare ex- 

 ceptions, and have almost been regarded as unnatural or monstrous, 

 so that we arrive, by a nearly imperceptible transition, at E. arvense, 

 in which the two kinds of stem are perfectly and constantly distinct. 



The figure at p. 727 represents two stems of the corn-field Equise- 

 tum, of the natural size, a a being the fertile, h h the barren stem : 

 they are drawn from living specimens, and show the immature barren 

 stem synchronous with the perfectly ripe fertile one, both stems as- 

 cending from the same rhizoma; and I may here remark that the ap- 

 pearance of the barren stem at this early period, is very similar in E. 

 sylvaticum, umbrosum, Telmateia and arvense, so that the figure re- 

 ferred to gives a good idea of them all. The fertile stem selected for 

 the figure, as one of average size and proportions, may be thus de- 

 scribed : it is about nine inches in length, and is divided into eight 

 joints, which decrease in length from the catkin downwards: the stem 



* Curtis, Flor. Lond. fasc. 4, t. 64. 



