N. ORD.--EOUISETACE as. 179 
GENUS.—E QUISETUM,* LINN. 3 
SEX, SYST.—CRYPTOGAMIA FILICES. 
HQUISETUM. 
GREAT SCOURING RUSH. 
SYN.—EQUISETUM HYEMALE, LINN. 
COM. NAMES.— SCOURING RUSH, DUTCH RUSH, SCRUBBING RUSH, 
A 
SHAVE-GRASS, WINTER HORSETAIL; (FR.) PRELE; (GER.) SCHACH- 
TELHALM. 
A TINCTURE OF THE WHOLE FRESH PLANT EQUISETUM HYEMALE, LINN. 
Description.—This erect, arrow-like plant grows to a height of from 1 to 3 or 
4 feet. Root perennial, horizontal, jointed like the stem, putting off from the sec- 
tions, at their middle, numerous moss-like rootlets. Svem simple, rarely incon- 
spicuously branched, sub-cylindrical from root to spike, hollow, evergreen, sur- 
viving the winter; 7zdges 17 to 27, very rough; ¢sdbercles in two more or less 
distinct lines on the ridges, constituting the roughness of the stem. Sheaths 
elongated, closely appressed to the stem at each joint, and furnished with a black 
zone at their bases; /’wé black, composed of as many teeth as there are ridges 
upon the stems; /ee¢h linnear, narrow, each with a keel at its base, appearing as 
a prolongation of the ridge below; the awned points deciduous. Epzdermis abound- 
ing in silex; s/omata disposed in two lines, one on each side of the groove. Spzke 
apical, ovate, armed with a sharp, rigid, black tip; sca/es with a dark, brownish- 
black face. 
Equisetacez and Equisetum.—This family of flowerless plants is very charac- 
teristically distinct, consisting of one genus only, the Lguzse/a, immediately recog- 
nized after once examined. They consist of fertile and sterile stems, often branched, 
and always jointed, hollow, and rough. The root, in its solid portion, is composed 
from centre to circumference of the following layers: strong cellular tissue; a 
circle of air-canals, each surrounded by a zone of vascular bundles; a circle of 
vascular bundles composed of annular ducts; a parenchyma traversed by air- 
canals; a circlet of parenchymatous cells; and the cuticle. As the rhizome 
approaches the stems it becomes hollow through the loss of the central cellular 
tissue and the modification of the other layers. The jointed stems and dranches — 
are hollow and bridged by a thin membranous diaphragm at each joint. The 
* Eguus, a horse; seta, a hair or bristle. 
