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Allium munzii

(Ownbey & Aase ex Traub) McNeal

Munz's Onion

G1Critically Imperiled Found in 3 roadless areas NatureServe Explorer →
G1Critically ImperiledGlobal Rank
Very high - highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.144778
Element CodePMLIL022Z0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderAsparagales
FamilyAmaryllidaceae
GenusAllium
Synonyms
Allium fimbriatum var. munziiOwnbey & Aase ex Traub
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.
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2016-05-26
Change Date1988-03-08
Edition Date2016-05-26
Edition AuthorsBittman, R.L., rev. Maybury (1997), rev. Gries (1998), rev. L. Oliver (2003), rev. A. Olivero (2003), rev. L. Oliver (2009), rev. Bittman and Treher (2016)
Threat ImpactVery high - high
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences6 - 20
Rank Reasons
Allium munzii is narrowly endemic to western Riverside County in southern California. Munz's onion is known from fifteen extant populations. It is extremely threatened by rapid and extensive urbanization, dry land farming activities, competition from non-native plants throughout its entire range, and off-road vehicle activities throughout a significant portion of its range. Other threats include, clay mining and grazing (CNPS 2001).
Range Extent Comments
Only known from the Gavilan Plateau and Temescal Valley regions in western Riverside County, California on clay soils (U.S. Fish and Wildlife Service 2004).
Occurrences Comments
Known from twenty populations with four being historic and one extirpated.
Threat Impact Comments
The foreseeable threat with the greatest impact is habitat degradation/loss. Allium munzii is extremely threatened by rapid and extensive urbanization in southern California. A housing development impacted a portion of a nearby occurrence, a freeway interchange greatly reduced another occurrence, and roads have bisected or reduced the population numbers of several occurrences (U.S. Fish and Wildlife Service 2004). Further, off-road vehicles and utility work continue to be threats. Clay mining is another great threat that has and continues to threaten populations of A. munzii, including one of the largest occurrences (U.S. Fish and Wildlife Service 2004). Crowding and competition for resources from two non-native grasses, Avena barbata and Bromus madritensis, threaten the majority of the populations (Fish and Wildlife Service 1998). Grazing, repeated cycles of fire and soil nitrification has allowed these non native grasses to invade making it difficult for A. munzii plants to penetrate the dense mats created by the grasses. The native habitats (native grasses, open sage scrub and chaparral) are patchy and easier for the rare species to emerge and penetrate through (U.S. Fish and Wildlife Service 2004).
Ecology & Habitat

Diagnostic Characteristics

Perianth 6-9 mm, white to pink, becoming darker. Infl compact, pedicels straight; perianth parts elliptic to ovate, obtuse to acute. This species can be distinguished from other similar alliums in its range by its single hollow, terete leaf; the shape of the perianth segments, flower color and irregularly dentate crest of the ovary (U.S. Fish and Wildlife Service 2004).

Habitat

Grassy openings in coastal-sage scrub. Soils are moist, heavy clays.

Reproduction

Three to five years are needed after seeds germinate before the plant reaches sexual maturity and produces flowers. The plant is dormant for most of the year except for the spring and early summer. This species flowers from March to May. Finally, this species responds to the varied amounts of rainfall from year to year which affect its emergence. In years with little rainfall few plants flower, and in years with good rainfall most plants bloom (U.S. Fish and Wildlife Service 2004).
Terrestrial Habitats
Shrubland/chaparral
Other Nations (1)
United StatesN1
ProvinceRankNative
CaliforniaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentPervasive (71-100%)Extreme - seriousHigh (continuing)
1.1 - Housing & urban areasPervasive (71-100%)Extreme - seriousHigh (continuing)
2 - Agriculture & aquaculturePervasive (71-100%)Extreme - seriousHigh (continuing)
2.1 - Annual & perennial non-timber cropsPervasive (71-100%)Extreme - seriousHigh (continuing)
2.3 - Livestock farming & ranchingPervasive - largeSerious or 31-70% pop. declineHigh (continuing)
3 - Energy production & miningPervasive (71-100%)Extreme - seriousHigh (continuing)
3.2 - Mining & quarryingPervasive (71-100%)Extreme - seriousHigh (continuing)
4 - Transportation & service corridorsPervasive - largeExtreme - seriousHigh (continuing)
4.1 - Roads & railroadsPervasive - largeExtreme - seriousHigh (continuing)
4.2 - Utility & service linesPervasive - largeExtreme - seriousHigh (continuing)
6 - Human intrusions & disturbancePervasive - largeSerious or 31-70% pop. declineHigh (continuing)
6.1 - Recreational activitiesPervasive - largeSerious or 31-70% pop. declineHigh (continuing)
7 - Natural system modificationsPervasive - largeExtreme - seriousHigh (continuing)
7.1 - Fire & fire suppressionPervasive - largeExtreme - seriousHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesPervasive - largeExtreme - seriousHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesPervasive - largeExtreme - seriousHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (3)
California (3)
AreaForestAcres
ColdwaterCleveland National Forest8,402
TrabucoCleveland National Forest23,341
WildhorseCleveland National Forest1,483
References (10)
  1. 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.
  2. Fiedler, P.L. 1996. Rare Lilies of California. California Native Plant Society Press, Sacramento, California. 154 pp.
  3. Flora of North America Editorial Committee (FNA). 2002a. Flora of North America north of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. Oxford Univ. Press, New York. xxvi + 723 pp.
  4. Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp.
  5. 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.
  6. Smith, J.P., and K. Berg. 1988. California native plant society's inventory of rare and endangered vascular plants of California. 4th edition. California Native Plant Society, Sacramento. 168 pp.
  7. Stephenson, J. R., and G. M. Calcarone. 1999. Southern California mountains and foothills assessment: habitat and species conservation issues. General Technical Report GTR-PSW-175. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. 402 pp.
  8. U.S. Fish and Wildlife Service (USFWS). 1994. Proposed rule to list four southwestern California plants as endangered or threatened. Federal Register 59(240): 64812-64823.
  9. U.S. Fish and Wildlife Service (USFWS). 1998. Endangered and threatened wildlife and plants: determination of endangered or threatened status for four southwestern California plants from vernal wetlands and clay soils. Federal Register 63(197):54975-54994.
  10. U.S. Fish and Wildlife Service (USFWS). 2004. Endangered and threatened wildlife and plants; proposed designation of critical habitat for <i>Allium munzii</i> (Munz's onion). Federal Register 69 (108): 31569-31572.