- Horsetail
LAWRENCE JENKINS
E. R. JACKMAN
HORSETAIL RUSHEqui,Mtum arvense Showing section of rootstock with tuberous
growths: roots, A; male part of plant, B;- and spore-producing part of plant, C. .
-
Oregon State System of Higher Education
Federal Cooperative Extension Service
Oregon State College
Corvallis
Extension Bulletin 554
July 1941
Horsetail
(Equisetum arvense)
By LAWRENCE JENKINS and E. R. JACKMAN*
Illustrations by Cathrine Davis Young
Other names: Scouring-rush, Foxtail-rush, Bottle-brush, Pinegrass,
Horsetail fern, Jointed-rush.
Horsetail is similar to fern in that it produces spores instead of seeds
and also spreads by underground rootstocks. The plant is common in moist
fertile fields and occurs in both eastern and western Oregon. In the early spring
it sends up numerous cylindrical, leafless, light-brown stalks that usually grow
8 or more inches high and have several joints along their hollow stems. Each
Joint is covered with a brown sheath that is notched along the top rim. At the
tip of each stem is a yellowish, honeycomb-appearing, club-shaped head. These
shoots are the fertile parts of the plant that mature and produce spores, then
wither and die in a few weeks. Later the same creeping root sends up papery,
hollow, sterile, jointed stems with numerous branches in whorls at regular
intervals along them. This part of the plant grows until frost ;; it is the part
most usually seen, and is commonly called "horsetail." The stems readily pull
apart at the joints. This second shoot manufactures plant food and stores it
in the roots for the next year's fruiting or spore-bearing stem and for use in
further root growth.
Peculiar fleshy tuberous growths are found at numerous points along the
rootstocks. These growths vary in size from to inch in diameter and are
arranged singly or in pairs on the roots. They serve as a storehouse for
reserve plant food in the form of available carbohydrates. Their location on the
roots varies from a few inches underground to a depth of 6 feet or more.
Livestock poisoning. This weed is poisonous to animals when fed in
large quantities. It is eaten very little when green and is reported to be relatively nonpoisonous then. The poisoning generally results from feeding it with
hay, and usually the symptoms do not occur in mature animals for some weeks.
Affected animals are reported to develop a craving for the weed, leaving good
hay for it.t Animals are affected in much the same way as when poisoned
by bracken fern. They lack muscular control and show weakness. Horses, and
particularly colts, are most susceptible, but there are reports of poisoning of
sheep and cattle. Often animals will not show any symptoms other than becoming out of condition ; and if they are given plenty of clean good-quality
hay and a dose of physic, they will recover.
Control. The rootstocks of horsetail are often very deep, making this
weed a difficult one to control. Two years of cultivation have failed to
eradicate this plant on the Experiment Station. It prefers wet conditions.
Drainage, followed by heavy applications of barnyard manure to stimulate
desirable vegetation, will often do much to eliminate it. The planting of a row
crop that is well cultivated, and unsparing use of the hoe will help suppress
it. A good stand of alfalfa will compete satisfactorily. Horsetail does not do
well in a heavy grass sod. Sodium chlorate applied at the rate of 4 pounds
to the square rod has given good control on the Experiment Station.
Extension Bulletin 510 explains other methods of control.
ACKNOWLEDGMENTS: The authors thank Dr. Helen M. Gilkey, Curator of the Herbarium, for reading the manuscript and checking the description of the plant. Professor
G. R. Hyslop, In Charge, Division of Plant Industries, made many helpful suggestions.
* E. R. Jackman is Extension Specialist in Farm Crops and Lawrence Jenkins is
Assistant Extension Specialist in Farm Crops at Oregon State College.
f Some Poisonous Plants of Idaho. Idaho Experiment 'Station Bulletin No. 86.
Cooperative Extension Work in Agriculture and Home Economics
Wm. A. Schoenfeld, Director
Oregon State College and United States Department of Agriculture Cooperating
Printed and distributed in furtherance of the Acts of Congress of May 5 and June 30, 1914