Trifolium amoenum - Greene
Showy Indian Clover
Taxonomic Status: Accepted
Related ITIS Name(s): Trifolium amoenum Greene (TSN 26213)
Unique Identifier: ELEMENT_GLOBAL.2.135645
Element Code: PDFAB40040
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Trifolium
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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: Trifolium amoenum
Taxonomic Comments: A distinct species in a genus of about 300 species, most abundant in north temperate regions.
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 16Sep2015
Global Status Last Changed: 16Mar1994
Rounded Global Status: G1 - Critically Imperiled
Reasons: Formerly known from about 25 sites in 7 counties along the central California coast, this species was believed extinct until 1993, when a single plant was rediscovered in Sonoma County. That site has now been developed and the species is considered extirpated there. Another population, the only native population currently extant, was discovered in 1996 in Marin County. Seeds from both of these sites were used (separately) to establish experimental populations between 1997 and 2006; the long-term fate of those sowings is uncertain. The Sonoma and Marin plants differ in their morphology, so establishment/conservation of both forms is important. After stability/increase 1997-2005, the native Marin population declined sharply in 2006; it is unclear whether and when it may recover its former numbers. Some experimental sites sown with seed of the Sonoma plant appear to have failed, but others have apparently established and are increasing. Loss of habitat to urbanization and agriculture was likely the primary reason for the extirpation of so many populations, and this habitat loss in continuing within the species' historic range, limiting the number of potential reintroduction sites. The extant native population is on private land, where threats include development, gopher grazing, potential erosion and trampling, and non-native plants.
Nation: United States
National Status: N1

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 California (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (22Oct1997)
U.S. Fish & Wildlife Service Lead Region: R8 - California-Nevada

NatureServe Global Conservation Status Factors

Range Extent Comments: Historically in Alameda, Mendocino, Marin, Santa Clara, Solano, Sonoma, Napa counties, California; currently believed extant only in Marin (native) and Sonoma (reintroduced) counties.

Number of Occurrences: 1 - 5
Number of Occurrences Comments: Had been thought extinct until the early 1990s. A single plant was found in 1993 at a site in Sonoma County, but that site has now been developed and the species is considered extirpated there. However, seeds were collected from the plant prior to its extirpation and were subsequently multiplied. In 2006, some of those seeds were used to establish experimental populations at two sites in Sonoma County and at several sites at Point Reyes National Seashore (Marin County). It is as yet unknown whether any of the experimental sowings will persist (USFWS 2007). Another population, the only native population currently extant, was discovered in 1996 in Marin County. In 1997, seed from those plants was used to establish a small experimental population (approximately 20 seedlings) at Bodega Marine Laboratory (Sonoma County) (USFWS 2007). The Bodega experimental population had persisted as of 2007, but its long term fate is unknown (USFWS 2007).

Population Size Comments: The one native occurrence had about 225 plants when it was discovered in 1996 (California Dept. of Fish and Game 2000).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Threats in the past were obviously very high, with habitat being lost to urbanization, agriculture, and (possibly) cattle grazing and/or competition from weedy non-native plants. Widespread urbanization continues throughout this species' historic range, and its current extreme rarity makes it precarious. Urbanization and agriculture may be preventing re-establishment of the plant from seed banks at historically-occupied sites (USFWS 2007). The single native population is located on private property in a developed area, and a house has recently been constructed within 100 feet of it. Future development plans on this property are not known. Gopher grazing is also a threat at this site and appears to have caused substantial recent mortality (USFWS 2007). This population is somewhat threatened by erosion because of its proximity to a coastal bluff, and could also be impacted by any potential expansion or increase in use of a small trail that runs through it to provide local homeowners with bluff access (USFWS 2007). Several non-native invasive plants, including Carpobrotus edulis, Lolium multiflorum, and Plantago lanceolata, are also present at this site and pose a potential threat (USFWS 2007). The Bodega Marine Laboratory experimental population is still very small and is located near heavily used buildings, although it is signed to prohibit unauthorized entry and reduce unnecessary foot traffic (USFWS 2007). Non-native plants including Medicago polymortha, Plantago coronopus, and Plantago lanceolata also occur in close proximity; laboratory staff currently mitigate this threat by weeding (USFWS 2007).

Short-term Trend: Decline of >10%
Short-term Trend Comments: At the single remaining native population, there is high interannual variability in number of plants and in seed production (USFWS 2007). Population status was rated as stable or increasing through 2005 with high seedling densities in some years (Peter Conners pers. comm. June 2003), but a sharp decline was observed in 2006. Compared to 2005, in 2006 seedling number had declined by 94% and seed productivity had declined by 98%; seed production was the lowest of the entire 10-year monitoring period with low plant numbers as well (Connors 2006 cited in USFWS 2007). It is too soon to know whether this sudden decline will continue, or whether the population will recover. In 2005, a few plants were identified about 500 meters north of the main population, five of which set seed; however, no plants were found at the northern site in 2006 (Connors 2006 cited in USFWS 2007). The Bodega Marine Laboratory experimental population is not routinely monitored, although it appeared to experience a decline similar to that of the native population between 2005 and 2006 (Connors 2006 cited in USFWS 2007). At the other experimental sites, germination has been documented at most (USFWS 2007). Of the sites planted at the Point Reyes National Seashore, some have failed, but others appear to have successfully established and are increasing (J. DiGregoria pers. comm. 2009).

Long-term Trend: Decline of >90%
Long-term Trend Comments: Historically known from 25 sites but probably extirpated at all but 1 of these (although some viable seed may remain in seedbanks and may germinate if conditions are right). Loss of habitat to urbanization and agriculture was probably the primary reason for the extirpation of so many populations. Even since 1997 when this species was listed as Engandered, much habitat potentially suitable for restoration has been altered and is now unsuitable due to urbanization, agricultural operations, and changes in the biological community and hydrological conditions (USFWS 2007).

Other NatureServe Conservation Status Information

Distribution
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Global Range: Historically in Alameda, Mendocino, Marin, Santa Clara, Solano, Sonoma, Napa counties, California; currently believed extant only in Marin (native) and Sonoma (reintroduced) 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 CA

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Marin (06041), Napa (06055)*, San Mateo (06081)*, Solano (06095)*, Sonoma (06097)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
18 Gualala-Salmon (18010109)+, Russian (18010110)+*, Lower Sacramento (18020163)+*, Suisun Bay (18050001)+*, San Pablo Bay (18050002)+*, Coyote (18050003)+*, San Francisco Bay (18050004)+*, Tomales-Drake Bays (18050005)+, San Francisco Coastal South (18050006)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: An annual herb, 1-6 dm tall, hairy and often robust. Leaves are divided into 3 egg-shaped leaflets. Flowers (April-June) are purple with white tips and are borne in dense, round or oval heads, 2-3 cm long.
Reproduction Comments: Mating system appears to include both cross-and self-pollination, as extant plants were found to have a higher level of heterozygosity than would be expected in a predominantly self-pollinating species (Knapp and Connors 1999 cited in USFWS 2007).
Terrestrial Habitat(s): Barrens, Cliff, Grassland/herbaceous, Shrubland/chaparral
Habitat Comments: Typically in low, wet swales in grasslands. Also on grassy hillsides at up to about 400 m elevation. Per the California Dept. of Fish and Game (2000): Open, sunny sites, sometimes on serpentine soil in coastal bluff scrub and valley and foothill grassland; most recently seen on a roadside that had been graded and on an eroding cliff face. Possibly requires disturbance-created openings for germination.
Economic Attributes
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Economically Important Genus: Y
Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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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: 14Aug1989
NatureServe Conservation Status Factors Author: Gardner, P.A., rev. Maybury (1997), rev. Maybury 2003, rev. K. Gravuer (2009)

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
Help
  • California Department of Fish and Game. 2000. Natural Diversity Database (RareFind 2), Version 2.1.2, January 25, 2000. Downloaded in 2003.

  • California Native Plant Society (CNPS). 2001. Inventory of Rare and Endangered Plants of California (sixth edition). Rare Plant Scientific Advisory Committee, David P. Tibor, Convening Editor. California Native Plant Society. Sacramento, CA. x + 388pp.

  • Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 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.

  • U.S. Fish and Wildlife Service (USFWS). 2007. Showy Indian Clover (Trifolium amoenum) 5-Year Review: Summary and Evaluation. Sacramento Fish and Wildlife Office, Sacramento, California. December 2007. Online. Available: http://ecos.fws.gov/docs/five_year_review/doc1876.pdf (Accessed 2009).

  • U.S. Fish and Wildlife Service. 1995. Proposed endangered status for nine plants from the grasslands or mesic areas of the central coast of California. Federal Register 60(148): 39314-39326.

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