620 EQUISETACEJE. (HORSETAIL FAMILY.) 
* * Stems evergreen, all alike, mostly branchless. (Stomata 1 -rowed.) 
5. E. liyentitle, L. (Scouring Rush. Shave-Grass.) Stems 
stout and upright (2P-3 0 high), 14-2 6-furrowed, the ridges rough with 
2 rows of minute tubercles; sheaths close, whitish, with the top and 
bottom black, with awl-shaped black teeth which are early decidu¬ 
ous, leaving a bluntly crenate margin. — Wet banks, common: well 
known for its use in scouring. June. — E. l^vigAtum and E. ro- 
BtisTUM, of Braun, allied to this, are to be sought along our southern 
and western borders. 
6. E. variegatum, Schleicher. Stems ascending (6 , -12 / 
long), simple, from a branched and tufted base, 5-9 -furrowed, the 
ridges rough with 2 rows of tubercles which are separated by a sec¬ 
ondary furrow; sheaths enlarged upwards , green variegated with black 
above; the teeth persistent, obtuse, tipped with a deciduous bristle. 
— Shores or river-banks, from Bellows Falls, Vermont {Carey), and 
Buffalo, to Michigan ; rare. 
7. E. scfrpoides, Michx. Stems thread-like, in dense little 
tufts (4' - 8' high), somewhat bent or curved, rough, % - A-grooved al¬ 
ternately with as many ovate bristle-pointed teeth, and with the same 
number of intermediate furrows of equal width; sheaths variegated 
with black; central air-cavity wanting. — Moist wooded hill-sides, 
common northward. 
Order 131. FLLICES. (Ferns.) 
Leafy plants , with the leaves (fronds) usually rising 
from prostrate or subterranean rootstocks , separately rolled 
up (circinate) in the hud (except in suborder 3), and bear - 
ing, on the veins of their lower surface or along the mar - 
gins, the simple fructification , which consists of \-celled 
spore-cases (sporangia), opening in various ways, and dis¬ 
charging the numerous minute spores. (The principal 
stalk, or petiole, of the frond is termed a stipe .) 
Synopsis, 
Suborder I. POLYPODlNEiE. (True Ferns.) 
Sporangia collected in dots, lines, or variously shaped clusters {sori 
or fruit-dots) on the back or margins of the frond or its divisions, 
stalked, cellular-reticulated, the stalk running into a vertical incom¬ 
plete ring, which by straightening at maturity ruptures the sporangi¬ 
um transversely on the inner side, discharging the spores. Fruit-dots 
often covered, at least when young, by a membrane called the involu¬ 
cre, or more properly the indusium. 
