| Ambrosia acanthicarpa | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Heliantheae |
| Genus: | Ambrosia |
| Species: | A. acanthicarpa |
| Binomial name | |
| Ambrosia acanthicarpa Hook. |
|
| Synonyms | |
|
Franseria acanthicarpa |
|
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 bracts 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.