Plant Image
Flower stalk

Yavapai County Native & Naturalized Plants

Ambrosia confertiflora - weakleaf bur ragweed

Synonyms: Frenseria confertiflora
Other Common Names: slimleaf bursage
Plant Form: Forb or Subshrub

Family: Asteraceae

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Flower stalk
Max Licher @
Max Licher @
Forb Plant Description

Origin: Native   Life Cycle: Perennial
General Desc: An erect, leafy somewhat bushy herb which can form large colonies.
Identification notes: Leaf blades are lanceolate to ovate and irregularly 2 to 4 pinnately lobed. Involucres (whorled bracts) of staminate (stamens without pistels) heads are 1/16 to 1/8 + inches in diameter. Spines of burs are awl shaped with hooked tips.
Height: 1 to 3 feet


Habitat Description: Grows in a variety of moisture and soil conditions. Usually found in open scrub and waste areas.
Plant Communities: Desert Scrub, Interior Chaparral, Semidesert Grasslands, Pinyon Juniper Woodland, Montane Conifer Forest, Riparian, Disturbed Areas
Elevation: 1000 - 7000 feet

Flower Characteristics

Color: Dull yellow to greenish     Shape: Daisy or dandelion-like in round clusters     Tubular: N     Flowering Period: Apr - Nov
Description: Small heads of tiny male flowers, each head enclosed in a drooping green cup. Female heads are clustered in the leaf axil below the male head. Flowers are wind pollinated.

Leaf and Stem Characteristics

Leaf Color: Light green     Leaf Type: Simple     Leaf Shape: Pinnatifid     Leaf Margin: Lobed     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: Leaves and stems     Spines: N
Leaf Description: Leaves can appear gray because of the many hairs and are 2 to 5 inches long. Narrow stems at ends of fuzzy, green and erect branches.

Fruit and Seed Characteristics

Fruit Color: Light brown (tan)   
Fruit Type: Achene
Fruit Notes: Fruits are beak-tipped and armed with 5 to 12 curved spines.
Seed Notes: The plant reproduces from both seeds and rootstock. Each bur contains 1 to 2 seeds.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 8.0  
Last Updated: Nov 21, 2021
Content Questions/Comments: Email Mary Barnes  
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