A NORTHERN ARIZONA HOMEOWNER’S GUIDE TO IDENTIFYING AND MANAGING INVASIVE PLANTS
Common name(s): Skeletonleaf bursage, bursage
Scientific name: Ambrosia tomentosa
Family: Sunflower or Aster family (Asteraceae)
Reasons for concern: Aggressively forms large populations by spreading roots and seeds, and can be difficult to control.
Special Note: Native plants have evolved together over centuries with pollinators, birds, wildlife and other native plants. We may not understand the role this native plant plays in our environment, so we may not want to completely eliminate it.
Botanical description: Erect, branching herbaceous plant.
Leaves: Mostly alternate, 2 to 5 inches long. Finely divided and deeply lobed with coarsely toothed margins. Lobes are reduced in size from leaf base to tip. Dark green upper leaf surface. Silvery-green lower leaf surface with fine, short, dense hairs.
Stem(s): Erect, 4” to 18” tall. Branched and spreading. Pale brown.
Flowers: Yellow. Very small and inconspicuous. Blossom June through September. Male flowers at top of stem, inflorescence resembles a spike. Spiny female flowers found below spike in leaf axils. Pollen drops from male flowers onto female flowers below producing seeds.
Seeds: Late June to August. Small, dry, hard.
Roots: Extensive, horizontal, deep, creeping roots.
Native to: Great Plains of U.S.
Where it grows: In disturbed habitats, in cultivated fields and pastures, prairies, streams, roadsides, waste areas, dry or poorly drained sites, at elevations of 4,200 to 7,000 feet.
Life cycle: Long-lived perennial
Reproduction: By seed and creeping roots
Weedy characteristics: Large root systems make this plant difficult to control.
Control strategies: Remove plants manually, making sure to get roots; till or hoe before plants flower. Disturb soil as little as possible. Step down disturbed soil. Plant desirable species to outcompete invasives. Frequently monitor previous infestations for new growth.
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