Common
Name(s):
Gray Horsebrush
Horsebrush
Spineless gray horsebrush
Scientific
Name:
Tetradymia
canescens DC.
Scientific
Name Synonyms:
None known
Symbol:
TECA2
Description:
Life Span: Perennial
Origin:
Native
Season: Warm
Growth Characteristics:
A
highly branched shrub, with spreading or ascending branches, growing
8 to 32 inches tall. It resembles sagebrush in color and growth
form. Flowers May to September and reproduces from seeds and root
sprouting.
Flowers/Inflorescence:
Flowers
are bright yellow to cream, with pale lemon color being the most
common. Long hairs surround the flowers. There are four to six bracts
per head, hence the name Tetradymia. The flowers are similar in
appearance to rabbitbrush flowers, only larger.
Fruits/Seeds:
Fruit is a densely silky achene.
Leaves: Alternate,
blades narrow lance-shaped, being ¾ to 1 inch long. The margins
are entire and the leaf has a prominent midvein. The surface is
wooly, giving the new leaves a silvery appearance.
Stems: Erect,
short, stout, highly branched. New growth is densely silvery hairy.
Older bark is gray, and shreddy. Old leaf bud scars appear swollen,
giving the stem a Knobby appearance.
Ecological
Adaptations:
Gray
horsebrush is common on barren plains and foothills, and in deserts,
at elevations from 4,400 to 10,500 feet. It is drought tolerant
and will thin out and drop its leaves in periods of water stress.
The occurrence of fire greatly enhances the ability of Gray horsebrush
to dominate a site.
Soils: Most
abundant on sandy or rocky soils.
Associated Species:
Douglas
rabbitbrush, big sagebrush, sandberg
bluegrass.
Uses and
Management:
Gray
horsebrush is poor to worthless as forage for cattle, sheep, goats,
and big game. It is consumed only when other forage is unavailable.
Gray horsebrush causes photosensitization in sheep. Symptoms are
called "big head" or "swell head" from swelling
of the head and facial features. Alkaloids may also cause liver
damage followed by death in sheep. Poisoning most often occurs in
the spring where good feed is lacking, and gray horsebrush is actively
growing. Abortion may also result from liver damage caused by the
toxins in gray horsebrush.
Sheep should be managed so as to avoid gray horsebrush. Most losses
occur during stormy periods and when trailing sheep through horsebrush
ranges. Consumption of black sagebrush enhances the toxic action
of horsebrush on sheep.
Hopi Indians made a tonic from the leaves and roots for uterine
disorders.
|
