Ambrosia linearis - (Rydb.) Payne
Linear-leaf Bursage
Other English Common Names: Streaked Bur-ragweed
Other Common Names: streaked bur ragweed
Taxonomic Status: Accepted
Related ITIS Name(s): Ambrosia linearis (Rydb.) Payne (TSN 36513)
Unique Identifier: ELEMENT_GLOBAL.2.143842
Element Code: PDAST0C0J0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Aster Family
Image 12083

Public Domain

 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Asterales Asteraceae Ambrosia
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Ambrosia linearis
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 29Jun2001
Global Status Last Changed: 25Jan2002
Rounded Global Status: G3 - Vulnerable
Reasons: 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.
Nation: United States
National Status: N3

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Colorado (S3)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Occurs in the shortgrass prairie region of east-central Colorado. It is found primarily in playas, but also on dry creek banks, particularly in the northern part of its range. It is also a common roadside plant within its range. Further inventory work is needed to establish the true extent of this species. Its approximate known distribution extends from Black Squirrel Creek to the west, the Arkansas/South Platte river divide to the northwest, Rush Creek to the north, northeast, and east, and the Arkansas River Valley to the south (Locklear 1989).

Endemic to Colorado (Elbert, Lincoln, Kiowa, El Paso and Pueblo counties)

Number of Occurrences: 21 - 80
Number of Occurrences Comments: 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. Similarly, it is likely that most or many of the playas within the range of this species are occupied by it, and in many areas there are from one to eight playas per square mile. It is likely that further research, while finding more occupied habitat, will cause the amalgamation of many currently known occurrences. There are hundreds, perhaps thousands, of playas that are almost certainly occupied by A. linearis.

There are 60 principal occurrences documented in the Colorado Natural Heritage Program data system. 3 of the 60 have not been observed in over twenty years.

Population Size Comments: Hundreds of thousands of individuals; often occurs in large, vigorous stands on roadsides. This species also has the ability to reproduce vegetatively (Locklear 1989) which may make population estimates difficult.

Overall Threat Impact Comments: Development of land for housing and agriculture pose the greatest threats to this species. The ephemeral creek bank and playa habitat of this species has been subject to significant disturbance and alteration throughout the range of this species, and further reduction of these habitats is ongoing. Many occurrences are eminently threatened by the rapid subdivision of southeastern El Paso County for residential development. Increased human and livestock densities and the presence of human infrastructure in this area will degrade the habitat quality, although the species does not appear to be grazed by livestock or wildlife (Locklear 1989). Historically many playas were excavated to create standing water for cattle but this seems to be an uncommon practice today. Roadside occurrences seem to be extirpated or mostly extirpated when roads are paved and the shoulder is planted with smooth brome (Bromus inermis). The species seems to tolerate disturbances such as road grading and mowing, but is a poor competitor. The species was reportedly common on the Ellicot Highway in El Paso County in 1993 but this occurrence was not found in 2000 following paving and smooth brome planting. Thus, as the human population increases and more roads are widened and paved within the range of Ambrosia linearis, it is expected that the roadside occurrences that are presently common will decline.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Unknown. Historically, this species was probably more abundant than it is today in the shortgrass prairie region of Colorado. It has recently moved into modified habitats (e.g. roadside ditches) and may actually be increasing again. This possible trend has not been quantitatively documented. Also, land-clearing for agriculture and roads have increased water runoff thus promoting the formation of additional potential habitat for this species (e.g. alluvial soils) (Locklear 1989). This possibility has not been explored.

Intrinsic Vulnerability Comments: This species occurs on disturbed sites, e.g. roadsides and ditches.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Occurs in the shortgrass prairie region of east-central Colorado. It is found primarily in playas, but also on dry creek banks, particularly in the northern part of its range. It is also a common roadside plant within its range. Further inventory work is needed to establish the true extent of this species. Its approximate known distribution extends from Black Squirrel Creek to the west, the Arkansas/South Platte river divide to the northwest, Rush Creek to the north, northeast, and east, and the Arkansas River Valley to the south (Locklear 1989).

Endemic to Colorado (Elbert, Lincoln, Kiowa, El Paso and Pueblo counties)

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States CO

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CO Denver (08031), El Paso (08041), Elbert (08039)*, Kiowa (08061), Lincoln (08073), Pueblo (08101)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
10 Middle South Platte-Cherry Creek (10190003)+, Kiowa (10190010)+*
11 Chico (11020004)+, Upper Arkansas-Lake Meredith (11020005)+, Horse (11020008)+, Upper Arkansas-John Martin (11020009)+, Big Sandy (11020011)+, Rush (11020012)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A perennial herb, 1-4 dm in height. Produces separate male and female flower heads (flowers June-August). Mature fruits are burr-like, with long, sharp spines.
General Description: Erect, shrubby perennial herb arising from a somewhat woody base. Growing from 6-12 inches in height. Leaves about one inch long and deeply divided into lobes. Upper surface of leaves dark green and lower surface white due to presence of numerous white hairs. Separate male and female flowers occur on each plane. Male flowers are creamy-yellow colored and occur in elongate clusters at tips of stems. Female flowers are small, occurring in the axils of the leaves. Fruit is a small "bur" with 4-9 spines.
Technical Description: From CNHP Wetland Guide 2012: Growth Habit: annual, herb, 2-4 dm tall, prominent taproot
Stems:
Leaves: once to twice pinnatifid, sessile, 1.5-2.5 cm long, with few narrow divisions, green above, densely tomentose on undersides, narrowly revolute, upper leaf surface green and lower surface white-wooly pubescent
Flowers: pistillate heads normally 1-flowered, 2-5 mm long, involucres bur-like, with long, sharp spines,
Fruit: mature achenes bur-like with long, sharp spines

Diagnostic Characteristics: From CNHP Wetland Guide 2012: Main Characteristics:
·Leaf margins and midrib contrast with white tomentose on underside of leaf
·1-flowered carpellate head

Reproduction Comments: Flowers appear in June and continue through early August; fruting continues through September (Spackman et al.).
Habitat Comments: Sandy or sandy clay soils in roadside ditches and in seasonally moist habitats in prairies. Frequently encountered in association with intermittent streams, ponds, or playas. 4,300 to 6,700 feet (Locklear 1990, 1989).
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Minimum Criteria for an Occurrence: Any naturally occurring population that is separated by a sufficient distance or barrier from a neighboring population. As a guideline, EOs are separated by either: 1 mile or more across unsuitable habitat or altered and unsuitable areas; or 2 miles or more across apparently suitable habitat not known to be occupied. Justification: The rationale for this large a separation distance across suitable but apparently unoccupied habitat is that it is likely additional inventory will find this habitat to be occupied. It can often be assumed that apparently unconnected populations will eventually be found to be more closely connected; these are best regarded as suboccurrences. No information on mobility of pollen and propagules is available on which to base the separation distance for this species.
Date: 30Sep2000
Author: Spackman, S., and D. Anderson.
Population/Occurrence Viability
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Excellent Viability: Size: 2000 or more individuals in a natural habitat (based on available EOR data). Condition: The occurrence has an excellent likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. This occurrence should be in a high-quality site with less than 1% cover of exotic plant species and/or no significant anthropogenic disturbance. An 'A' ranked occurrence may be one large playa or several smaller playas that have had little or no excavation or tilling in the past. In the northern part of the range of this species, a dry creek bank may also provide appropriate habitat. Grazing of the occurrence by cattle or prairie dogs is moderate. Landscape Context: The occurrence is surrounded by an area that is unfragmented and includes the ecological processes needed to sustain this species. The hydrologic regime should be unaltered by roads, irrigation, or other alterations. The occurrence should be surrounded by a primarily untilled landscape, though relictual small areas that were tilled by homesteaders may be present in the area. Justification: On road shoulders, viable populations of hundreds of thousands that extend for many miles are possible, but due to their unnatural ecological context these occurrences are considered "D" ranked occurrences. Large populations in high quality sites are presumed to contain a high degree of genetic variability, to have a low susceptibility to the effects of inbreeding depression, and to be relatively resilient.
Good Viability: Size: 1000 or more individuals in a natural habitat (based on available EOR data). Condition: The occurrence should have a good likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. Anthropogenic disturbance within the occurrence is minimal. However, the playa in which an occurrence is located may have been excavated in the past. Occurrences on dry creeks may be disturbed by heavy grazing or human impacts such as vehicle traffic. Grazing is moderate. If exotic species are present, they comprise less than 10% of the total ground cover. Landscape Context: The surrounding landscape should contain the ecological processes needed to sustain the occurrence but may be fragmented and/or impacted by humans. Limited fragmentation due to mobile home development or agriculture may be present in the area but the landscape is predominantly undeveloped rangeland.
Fair Viability: Size: 10 to 1000 individuals in a natural habitat (based on available EOR data). Condition: The occurrence may be less productive than the above situations, but is still viable, with multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. The occupied habitat is somewhat degraded. "C" ranked occurrences are often in playas that have been excavated, may have one or more roads passing through them, may contain cattle watering tanks or other equipment, and may be otherwise anthropogenically altered. Grazing may be moderate to heavy, with significant areas of bare ground due to trampling. In such situations, the population of Ambrosia linearis may be higher than in "A" and "B" ranked occurrences, but the rank is reduced due to the unnatural ecology of the occurrence. Exotic plant species make up between 10-50% of the total ground cover. Exotic species that are likely to be observed in Ambrosia linearis occurrences are Glandularia bipinnatifida, Medicagosativa, Melilotus spp., Bassia sieversiana, Carduus nutans, and Salsola australis. Landscape Context: There may be significant human disturbance, but the ecological processes needed to sustain the species are still intact.
Poor Viability: Size: Less than 10 individuals in a natural habitat, or any number of individuals in an unnatural habitat, such as a road shoulder (based on available EOR data). Condition: In natural occurrences, little or no evidence of successful reproduction is observed (poor seedling recruitment, no flowering or fruiting observed, or poor age class distribution). Exotic plant species make up greater than 50% of the total ground cover, and/or there is a significant level of human disturbance. Landscape context: The surrounding area is fragmented with many ecological processes no longer intact. A severely altered hydrologic regime that precludes the persistence of Ambrosia linearis is one such scenario. The occurrence may be surrounded by significant development, or may be so poorly mismanaged that the occurrence is nearly extirpated. In roadside occurrences, the population may be in the tens to hundreds of thousands and appear healthy and vigorous. Plants are even observed growing through cracks in pavement in such occurrences. However, such occurrences are not natural, and their persistence in solely dependent on the way the road is managed. Some such occurrences have been observed to be wholly or mostly extirpated when the road is paved and planted with smooth brome. The occurrence has a low probability of long-term persistence due to inbreeding depression, natural stochastic events, and its intrinsic vulnerability to human impacts.
Justification: Justification: On road shoulders, populations of hundreds of thousands that extend for many miles are possible, and although these occurrences are viable they are considered "D" ranked occurrences due to their unnatural ecological context. EOs not meeting "C"-rank criteria are likely to have a very high probability of inbreeding depression and extirpation due to natural stochastic processes and/or occur in degraded habitat with low long-term potential for survival. Although 50 individuals is the commonly recognized threshold for the short-term viability of a population, a C-rank cutoff of 10 individuals is recommended here to allow for observer error (failure to see all of the individuals) and year to year variation in the population size.
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 30Oct2000
NatureServe Conservation Status Factors Author: KETTLER, S.M., rev. DT Wasinger, Spackman/Maybury (1996), rev. Anderson, D. (2000)

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.


  • Flora of North America Editorial Committee. 2006c. Flora of North America North of Mexico. Vol. 21. Magnoliophyta: Asteridae, part 8: Asteraceae, part 3. Oxford Univ. Press, New York. xxii + 616 pp.

  • Great Plains Flora Association. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, KS. 1402 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Locklear, J. 1990. A Colorado speciality: Ambrosia linearis. Colorado Native Plant Society. Aquilegia 14(5):10.

  • Locklear, James H. 1989. Status of Ambrosia linearis in Colorado. Unpublished report prepared for the U.S. Fish and Wildlife Service, Denver, CO.

  • Locklear, James H. 1989. Status of Ambrosia linearis in Colorado. Unpublished report prepared for the US Fish and Wildlife Service, Denver, CO.

  • Rydberg, P. A. 1905. Studies on the Rocky Mountain Flora XIV. Bullentin of the Torrey Botanical Club 32(3): 123-138.

  • Ryke, N., D. Winters, L. McMartin and S. Vest. 1994. Threatened, Endangered and Sensitive Species of the Pike and San Isabel National Forests and Comanche and Cimarron National Grasslands. May 25, 1994.

  • Spackman, S., B. Jennings, J. Coles, C. Dawson, M. Minton, A. Kratz, and C. Spurrier. 1997. Colorado rare plant field guide. Prepared for Bureau of Land Management, U.S. Forest Service and U.S. Fish and Wildlife Service by Colorado Natural Heritage Program.

  • USDA, NRCS. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

  • Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Eastern Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 555 pp.

  • Weber, W.A., and R.C. Wittmann. 1996a. Colorado flora: Eastern slope. Revised edition. Univ. Press of Colorado, Niwot, Colorado. 524 pp.

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