Nores on HiIppocHakEtTE 75 
sidered, and it has not been until very recently that it 
has been proved that there were annual-stemmed 
species amongst the scouring rushes of America. Braun’s 
description calls for a species with a smooth stem, having 
the leaves of the green sheath with one central ridge on 
the lower half and two lateral ridges on the upper half, 
the central one being depressed and flattened out in 
that section, the teeth being caducous and leaving a 
truncate-dentate margin to the sheath; and with obtuse 
spikes. The contrasting characters of Eaton’s var. 
intermedium are a smooth or more generally rough stem, 
ash-grey sheaths with a black band above and below, 
caducous teeth leaving a crenulate margin and apiculate 
spikes. In Braun’s explanatory remarks, ‘‘The sheaths, 
as has been stated, have generally only a narrow black 
limb, but some specimens have also, especially on the 
lower sheaths, a black girdle at base; in one specimen I 
have seen the whole sheath black,” there is a hint that 
the intermediate plant was included in the species but 
no part of the description was drawn from it and it 
certainly was not considered as the type. The trans- 
ference, therefore, of the name laevigatum from the 
Smooth, annual stemmed species, for which it has so 
long and appropriately stood, to a rough perennial- 
stemmed species has been made without solid founda- 
tion of fact and should not be generally accepted. 
Equisetum Kansanum Schafiner = E. laevigatum A. Br. 
= Hippochaete laevigata (A. Br.) Farwell. 
Hrprocuarrp PREALTA. 
Both Rafinesque’s and Braun’s descriptions of their 
respective species (Equisetum prealtum and E. robustum) 
Were of the largest (40 or more ridges and leaves to the 
stem), and oldest forms (sheaths with deciduous teeth 
eaving a truncate margin). Engelman’s E. robustum 
var. minus was a smaller (28-31 ridges and leaves) 
