EQUISETACKiE. 163 



sheath, so that by their fall the sheath is left truncate and crenate ; 

 these crenatures correspond with the bases of the teeth. Branches 

 absent or very rarely produced, and then solitary, resembling the 

 stem in miniature, with its first internode much shorter than the stem- 

 sheath, below which it is produced ; sheath enclosing the first inter- 

 node of the branch pitchy-black, shining, oblique ; sheaths at the 

 apex of the first and succeeding internodes of the branch terminated 

 by triangular teeth with deciduous subulate scarious points. Spike 

 oval- or roundish-ovoid, acuminated and mucronate, pitchy-black or 

 pitchy-brown, its base embraced by the persistent teeth of the upper- 

 most stem-sheath. 



In moist woods and on wet banks and bogs, and in wet places 

 amongst sandhills, rare, from Kent, Surrey, Hereford, and Glamorgan 

 to Aberdeen, Banff, Elgin, Ross, Perth, Lanark, and Ayr. Rare, but 

 distributed from north to south of Ireland. 



England, Scotland, Ireland. Perennial. Late Summer, Autumn. 



Rootstock creeping, black, hollow. Stems 1^ to 2| feet high; 

 usually about the thickness of a goose-quill or a swan-quill, so rough 

 on the ridges as to make a distinctly grating sound when the finger- 

 nail is drawn along them ; spaces between the ridges transversely 

 rugose, with a line of stoma ta sunk in depressions at the base of the 

 ridges on each side. Sheaths usually about J inch long, appearing 

 truncate by the scarious part of the teeth separating as the stem 

 developes. The teeth of the uppermost sheath, which is funnel-shaped 

 and embraces the base of the spike, are always persistent, and are 

 slightly rough and crisped or twisted. Very rarely the teeth of the 

 stem-sheaths are persistent, in which case they are at first black, but 

 afterwards become hyaline. Branches rarely produced. I possess 

 but a single specimen which has a branch from near the apex of the 

 stem; it was gathered by Mr. Roy, at Banchory, Kincardineshire. 

 Spike 5 to ^ inch long. 



The stems survive the winter, but are more or less killed at the 

 apices, and in severe winter sometimes down to the ground. 



From the roughness of the stems caused by particles of silica, they 

 are capable of being used " as a file in polishing wood, ivory, or even 

 brass. This purpose it has long served in England, under the name 

 of Dutch Rushes, being usually imported from Holland." (Sm. Eng. 

 Flor. vol. iv. p. 340.) 



Rough Horsetail ; Dutch Rush ; or Shave-grass. 



