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Western Ragweed
Common
Name(s):
Ragweed
Western Ragweed
Cuman Ragweed
Scientific
Name:
Ambrosia
psilostachya DC.
Scientific
Name Synonyms:
Ambrosia californica
Rydb.
Symbol:
AMPS
Description:
Life
Span: Annual
or Perennial
Origin:
Native
Season: Warm
Growth Characteristics:
Western
ragweed's main stem rises from shallow or deep, branching rhizomes
which extend down 3 to 6 feet. Stems are slender and branched, usually
1 to 2 feet tall.
Flowers/Inflorescence:
Generally
inconspicuous male flowers occur in small heads on the upper part
of the flowering stalks, mostly in August and September. Female
flower heads are few and clustered near the base of the flowering
stalks at the point of attachment of the upper leaves.
Fruits/Seeds:Fruit
is an achene with a short beak and small blunt tubercles on top.
Leaves: Opposite,
becoming alternate above. Most of the leaves are rough-surfaced
and deeply pinnately lobed in irregular patterns.
Ecological
Adaptations:
Western
ragweed grows on dry prairies, blowouts, hills, and in washouts,
sandy woods, and meadows. It is also a widespread weed in waste
places, roadsides, railroads, overgrazed rangeland, and other disturbed
areas. Western ragweed is not drought resistant.
Western ragweed colonizes sites by means of spreading rhizomes,
allowing it to propagate when conditions are unfavorable to seedling
establishment.
Soils: Found
on a variety of soils, but does best on loam soils.
Associated Species:
Russian
thistle, curlycup gumweed.
Uses and
Management:
Because
of their bitter taste, ragweeds are seldom grazed. The bitter taste
is due to the foliage and stems containing cinnamic acid and sesquiterpene
lactones. However, western ragweed is not considered a poisonous
plant. Still, it is moderately important as ungulate forage. Western
ragweed is used for food and nesting material, and as a habitat
component by small mammals and nongame birds.
Western ragweed is a major invader of deteriorating rangeland. It
readily moves into open habitat.
All ragweeds produce abundant pollen, a primary hay fever producing
agent in late summer. Tea made from the leaves was used by American
Indians to relieve swelling and to stop vomiting. Tea was also used
to treat bowel cramps, bloody stools, and colds. It was also made
into a salve to treat skin sores of man and horses.
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