Linear-leaf Bursage / Center For Plant Conservation
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Plant Profile

Linear-leaf Bursage (Ambrosia linearis)

A closeup of this rare member of the ragweed family with yellow flowers. Photo Credit: J. Locklear
  • Global Rank: G3 - Vulnerable
  • Legal Status: N/A
  • Family: Asteraceae
  • State: CO
  • Nature Serve ID: 143842
  • Lifeform: Subshrub
  • Date Inducted in National Collection: 02/10/1987

It may be surprising to find a rare plant in a genus known for its weeds, but such is the case of the Colorado bursage. Known only from the high plains of eastern Colorado, this ragweed relative is associated with unique, temporary rainwater basins known as playa lakes, as well as other seasonally-moist habitats. The cycle of filling and drying in such places creates a natural disturbance of the shortgrass prairie vegetation, and provides a specialized niche for the Colorado bursage. Elevation 4300-6700 ft.

Where is Linear-leaf Bursage (Ambrosia linearis) located in the wild?


Seasonally moist habitats including playa lakes, intermittent streams, small prairie depressions, and county road edges and ditches within shortgrass prairie. Occurs at the upper margins of playa basins and on terraces just above stream beds. Plants growing in these natural settings tend to be scattered, while those growing at roadsides often occur in very dense stands.


Limited to the plains of eastern Colorado in El Paso, Kiowa and Lincoln counties.

States & Provinces:

Linear-leaf Bursage can be found in Colorado

Which CPC Partners conserve Linear-leaf Bursage (Ambrosia linearis)?

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

  • 08/26/2020
  • Propagation Research

Seed germination studies.

Nature Serve Biotics
  • 05/02/2017

This species is a restricted endemic of Colorado with significant threats to its distribution and abundance. It is likely that populations of this species are to be found on most of the playas within its range. The G rank is based on occurrences in natural ecological settings for this species, which are usually playas and dry creek banks, and occasionally shortgrass prairie uplands. Because this species is so common on the roadsides within its range, there is a great deal of connectivity between many of the known populations. Using the 2 mile separation distance, most of the eastern half of El Paso County is one vast roadside occurrence of this species, and this is likely to be true in other parts of its range as well. To facilitate data management, it was decided to break this occurrence up and manage the data by quad. Thus, when the roadsides are considered, the number of occurrences is artificially inflated. Most factors (range, abundance, and number of occurrences) suggest that a rank of G3 is warranted for this species. However, the threats to the natural habitat for this species are great, due to the rapid ongoing transformation of the landscape in the area indicating a rank of G2G3 may be warranted. There are less than five A-ranked occurrences of this species known at present, and only one natural protected occurrence of this species (Bohart Ranch). If long term protection is not established and assured for several high quality natural occurrences, and more high quality natural occurrences are not found, a G2 rank may be warranted.

Jim Locklear
  • 01/01/2010

Activities that cause alteration/degradation of playa lakes. Plowing and planting habitat to crops. Excessive livestock concentration leading to trampling.

Jim Locklear
  • 01/01/2010

Probably 50-75 ""populations,"" but many of these are roadside occurrences that occupy ditches. Actual number of populations in high quality natural habitat such as playas and stream terraces is much less, perhaps less than 10 (Locklear 1989).

Jim Locklear
  • 01/01/2010

None known.

Jim Locklear
  • 01/01/2010

Not Available

Jim Locklear
  • 01/01/2010

Population montoring. Location and protection of high quality natural occurrences.

Jim Locklear
  • 01/01/2010

Seed germination studies.


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Taxon Ambrosia linearis
Authority (Rydb.) Payne
Family Asteraceae
CPC Number 102
ITIS 36513
Duration Annual
Common Names Colorado bursage | linear-leaf bursage | plains ragweed | ragweed | streaked ragweed
Associated Scientific Names Ambrosia linearis | Franseria linearis
Distribution Limited to the plains of eastern Colorado in El Paso, Kiowa and Lincoln counties.
State Rank
State State Rank
Colorado S3
Ecological Relationships


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