2e Ee arvense Le Common Field Horsetail. Coarse pale-green plants, the 
q stems commonly several from slender rhizomes, 30-60 cm, tall, 6-19 furrowed, 
the grooves open, prominent; sheaths loose, the lowermost spreading upwards, 
9-11 mm, long, dark or brown-black, with slender acuminate teeth, those of 
midstem subappressed, of the slender branches inconspicuous, ovate, with 
abruptly acuminate bristle-tipped teeth, these closely appressed; strobilus 
borne on short unbranched spring shoot, followed by the several sterile 
summer herbaceous shootse 
Common in springy places, moist roadsides and damp woods, forming 
often dense colonies of ay hundred plants. Forma proliferum (Luerrs,) 
Breun, with cones borne onltivs of sterile leafy summer shoots, agFish (from) 
Lake, Epling & Houck 9727, is occasional over the whole cosmopolitan range 
of the species. - 
Se E. palustre var. americanum Victorin. Marsh Horsetail, Slender plants, their 
i (SGersycommonly arising singly from a slender rootstock, +setems lax or even 
decumbent upon herbage, 4C-60 cm, tall, of 1 kind, prominently deeply 5-9 
grooved, the furrows separated by thin wing-like ribs not harsh toftouch; Che) 
sheaths loose, all spreading upwerds and thus basket-like, the lowermost 
and those of{midstem 11-13 mm, long, with pale, brown-margined lance-acuminate 
RRR 
teeth, those of|divaricate branches 2-3 mm, long, the teeth erect or 
spreading; strobilus crowning the ordinary herbaceous shoots in summer, 
bluntish or barely acute, commonly borne well above the remote whorls of 
subtending branches of shoot. 
Known in our region only from Priest R, drainage, in wet meadows at 
elevations of about 3000 feet, as at Hughes Mdw., Epling 7362, 
