Scientific Family
Asteraceae
Synonyms
Acanthoxanthium spinosum, Xanthium spinosum var. inerme
Other common names
Bathurst burr
cocklebur
Plant type
Forbs and Subshrubs
Origin
Introduced
Lifecycle
Annual
Height
4 to 24 inches tall
Riparian
Yes
Annual herbs, stems erect, branched, with 1 or 2 gold-colored spines at each node; spines unbranced or 3-branched, 1/2 to 1-1/4 inches long or longer; flowers unisexual.
Stems erect, branched, with paired, gold, unbranched or 3-branched spines; leaf blades lance-like to oval to narrow, often shallowly lobed, upper surface shiny dark green, lower densely white or gray hairy; tiny, unisexual flower clusters, female above.
Habitat
Found mostly near Prescott and the Verde Valley in Arizona, disturbed, seasonally wet, often alkaline (pH greater than 7.0) sites; especially grasslands, marshes and watercourses, margins of agriculture.
Plant Community
Riparian
Grasslands
Disturbed Areas
Low elevation
3000
High elevation
7000
Flower Characteristics
Rounded clusters of male flowering heads, with 1 or 2 female heads near the tip; clusters terminal or in leaf axils. Male flowers have translucent petals, female flowers lack petals.
Flower color
Greenish
Flower shape
Regular
Tubular
No
First bloom month
July
Last bloom month
October
Flower clusters
Rounded
Leaf and Stem Characteristics
Herbage mostly hairy; blades oval to lance-like or narrow, to 5 inches long, often 3 to 7 or more lobes, lower surfaces grayish-white, densely hairy, upper dark shiny green, short stalked, 1-1/2 to 3 inches long.
Leaf type
Simple
Leaf color
Dark green, grayish-white
Leaf shape
Narrow
Leaf margin
Lobed
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
Yes
Fruit and Seed Characteristics
Fruit is a broadly cylindric burr, about 1/16 inch long, yellow to brown, with slender spines.
Fruit type
Other
Fruit color
Yellow to brown