EQUISETUM. 
215 
to the Dutch rush, and Sir W. Hooker ranks it as inter- 
mediate between that species and the Variegated Rough 
Horsetail. The sheaths are 
pale greenish-brown in youth, 
but ultimately become black, 
and the teeth are awl-shaped. 
A seetion of the stem shows 
scarcely perceptible ridges on 
the exterior surface, a circle 
of apertures large, egg-shaped, 
and, as usual, placed beneath 
the furrows, the narrower end 
of the egg turned inwards ; 
and an inner circle of small 
round ones near the inner 
surface of the tube. 
This plant is rare ; the ha- 
bitats ascertained are the glens of North Ireland, and 
the banks of the Dee. 
It is also found in Germany. 
Mr. Newman, Mr. Moore, and others call this species 
E. Mackaii . 
66. Rquisetum variegatum, Schleich. Variegated 
Rough Horsetail. 
Caudex widely creeping. Stems numerous, slender, branched 
at the base. Sheaths with about ten bristle-pointed teeth. Cone 
small, generally sessile, pointed. 
The stems of the Variegated Rough Horsetail are 
branched so freely just beneath the earth that it gives 
them almost a tufted appearance ; the roots grow in 
whorls, and the branches are generally simple, though 
occasionally bearing one or two branchlets. It is a 
