Data provided by the participants of the Consortium of California Herbaria

View additional distribution information on the Jepson eflora

Ambrosia acanthicarpa is a species of ragweed known by the common names flatspine burr ragweed, annual burrweed, and annual bur-sage. This spiny, weedy plant grows in clumps of many erect stems which may reach over a meter in height. Its gray-green stems are covered in a coat of stiff, bristly hairs. The few rough leaves are several centimeters long. The racemes of flowers are more plentiful, with each hairy flower head a few millimeters wide. The spiny, burr-like pistillate heads have pointed, twisting leafs and the staminate heads are rounded. This ragweed is native to western North America. It is adaptable and grows well in disturbed areas, easily becoming weedy.

Plant type

Annual herb

Size

3 - 5 ft Tall

Calscape icon
Color

Cream

Flowering season

Summer, Fall

Sun

Full Sun, Partial Shade

Water

Very Low

Ease of care

Moderate

Soil drainage

Fast

Site type

Sandy plains

Plant communities

Coastal Sage Scrub, Foothill Woodland, Valley Grassland

Caterpillars
Butterflies

Butterflies and moths supported

1 confirmed and 21 likely

Confirmed Likely

Ambrosia Plume Moth

Adaina ambrosiae

Garden Webworm Moth

Achyra rantalis

Ancylosis morrisonella

Animomyia smithii