Allium aaseae - Ownbey
Aase Onion
Other English Common Names: South Idaho Onion
Other Common Names: South Idaho onion
Taxonomic Status: Accepted
Related ITIS Name(s): Allium aaseae Ownbey (TSN 42638)
Unique Identifier: ELEMENT_GLOBAL.2.129345
Element Code: PMLIL02010
Informal Taxonomy: Plants, Vascular - Flowering Plants - Lily Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Liliales Liliaceae Allium
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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: Allium aaseae
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 02Apr1990
Global Status Last Changed: 02Apr1990
Rounded Global Status: G3 - Vulnerable
Reasons: Although there are nearly 30 known sites, all but a few face direct threats.
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 Idaho (S2S3)

Other Statuses

Comments on USESA: Until the U.S. Fish and Wildlife Service revised their candidate system, Allium aaseae was a federal category 1 candidate for listing under the Endangered Species Act. Under the revised system, it is no longer a federal candidate species.

NatureServe Global Conservation Status Factors

Range Extent Comments: Aase's onion is endemic to southwestern Idaho, occurring in the foothills around Boise and arcing northwest to near Emmett, an aerial distance of approximately 18 miles. In the Boise Foothills, the easternmost populations are known from the Hulls Gulch and lower Cottonwood Creek areas, while the Freezeout Hill vicinity near Emmett contains the westernmost foothill populations. Disjunct populations have recently been confirmed from near the towns of Payette and Weiser, northwest of the species main range. Populations previously reported from the Danskin Mountains, east of Boise are really Allium simillimum. Populations are located in Ada, Boise, Gem, Payette, and Washington Counties.

Number of Occurrences: 21 - 80
Number of Occurrences Comments: 29 recently seen.

Population Size Comments: Probably between 5000-10,000 individuals. A rangewide population estimate for Allium aaseae is 400,000 plants. This is a conservative number for a number of reasons: 1) the full extent of a number of occurrences is unknown, and it is very likely additional plants occur in unsurveyed suitable habitat; 2) no population estimates are available for five occurrences and their contributions remain uncounted in the above rangewide tally; 3) for populations or subpopulations estimated at 10,000+ plants, only 10,000 were added to the tally; 4) although the majority of areas likely to support plants have been searched, some places, especially on private lands remain unsurveyed; 5) plants that are not flowering are difficult to see and their numbers are likely underestimated during field investigations. This conservative estimate of 400,000 plants reflects increased survey work for this species over the years. For instance, in 1978, Holsinger (1978) estimated less than 15,000 individuals rangewide, while ten years later Moseley and Caicco (1989) estimated 260,000 plants for 57 location sites. For the 68 occurrences of Allium aaseae, 17 (26%) are estimated to contain more than 10,000 individuals, 33 (49%) are estimated between 1000-10,000 plants, 12 (17%) are estimated between 100-1000 plants, and only one (1%) at fewer than 100. Abundance information is unknown in five (8%) instances.

Overall Threat Impact: Unknown
Overall Threat Impact Comments: All but a few known sites directly threatened by dirt bikes, mining, ORVs, grazing, and/or housing developments.

Intrinsic Vulnerability Comments: Adapted to substrate instability, but probably intolerant of extreme disturbances.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Aase's onion is endemic to southwestern Idaho, occurring in the foothills around Boise and arcing northwest to near Emmett, an aerial distance of approximately 18 miles. In the Boise Foothills, the easternmost populations are known from the Hulls Gulch and lower Cottonwood Creek areas, while the Freezeout Hill vicinity near Emmett contains the westernmost foothill populations. Disjunct populations have recently been confirmed from near the towns of Payette and Weiser, northwest of the species main range. Populations previously reported from the Danskin Mountains, east of Boise are really Allium simillimum. Populations are located in Ada, Boise, Gem, Payette, and Washington 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 ID

Range Map
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U.S. Distribution by County Help
State County Name (FIPS Code)
ID Ada (16001), Boise (16015), Gem (16045), Payette (16075), Washington (16087)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
17 Lower Boise (17050114)+, Middle Snake-Payette (17050115)+, Payette (17050122)+, Weiser (17050124)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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General Description: Allium aaseae onion is an early spring-flowering member of the lily family. It is perennial with an underground bulb that is usually buried at least a couple inches below ground level in mature individuals. Bulb coat reticulations may or may not be evident. The scape is round to slightly flattened, not winged. The two linear, channeled leaves are 1-4 mm wide, at least twice as long as the scape and typically lying on the ground when observed in the field early in the season. Its six similar-looking tepals are pink, often richly so, but fading to white, 6-9.5 mm long, and with entire to obscurely or strongly denticulate margins. Stamens are shorter than the tepals, the undehisced anthers and pollen are yellow.
Technical Description: Bulb ovoid, outer coats brownish, usually with obscure reticulations, the cells of which are transversely elongate and intricately contorted, the inner coats white to pink or reddish; scape (3) 5-11 (15) cm long, terete or slightly flattened, not winged; leaves two per scape, linear, channeled, 1-3 (4) mm wide, entire or the margins obscurely denticulate, 2 or more times longer than the scape, green (ie. not withering) at anthesis, tending to be deciduous at maturity; bracts of the inflorescence 2 (3), ovate, obtuse to acuminate; umbel 5-25-flowered, pedicels shorter than or +/- equal the perianth; perianth segments (6) 7-9.5 mm long, lanceolate to elliptic, entire to erose to obscurely or strongly denticulate with minute +/- glandular teeth, erect, flaring at the tips, bright pink, fading with age or pressing, rarely white; stamens 1/2-2/3 as long as the perianth; anthers yellow, pollen yellow; ovary crestless or with three minute 2-lobed central processes, style included, stigma punctate, entire, capsule crestless (McNeal 1993).
Diagnostic Characteristics: There are several onion species occurring within and near the range of Allium aaseae. Allium aaseae is most likely to be confused with A. simillimum, especially at mid-elevations in the Boise Foothills, where their distributions nearly overlap. Populations with purple-mottled anthers may actually be hybrids between the two species. The following key, adopted from McNeal's (1993) key to the onions of southwestern Idaho, can be used to distinguish the two:

Allium simillimum. Perianth segments white with green or reddish midveins, sometimes flushed with pink; anthers purple or mottled purple and white, pollen white or grayish; denticulations, particularly on the inner perianth segments obvious under a hand lens and regularly distributed on the distal 2/3 of the segment; occurring above 4200 feet elevation on various substrates.

Allium aaseae. Perianth segments bright pink with rarely a white individual in an otherwise pink population; anthers yellow, pollen yellow, denticulations +/- irregular in number and distribution on perianth segments, often missing on plants from Rebecca Sand Hills RNA; usually restricted to lacustrine sands of the Glenns Ferry Formation, generally below 3700 ft., except in Cartwright Canyon where occurring up to 5100 ft. elevation.

Duration: PERENNIAL
Reproduction Comments: Allium aaseae reproduces from both seed and bulb division. Seed viability from different sites is variable, as is often the case in wild pant populations. The mean viability from four sites studied by Prentice (1988) was 55%. The number of seeds per pound is estimated to be 622,000 (Prentice 1988). Seed production is also variable from year to year (Prentice 1989). The pollination biology of Allium aaseae is unknown, although it has been reported to have no specific pollinators, and flowers visited by many types of insects (Bolin and Rosentreter 1986). This species flowers early in the season and likely makes use of any insect taxa active at this time of year. Seed dispersal mechanisms are unknown, but probably at least partly relies on the dried, detached umbel being blown around (Packard 1979).
Ecology Comments: There is little quantitative data regarding the effects of herbivores, disease, competition, hybridization or allelopathy on population viability. No native plant species appear to substantially compete with Allium aaseae for moisture, and only red three-awn seems to compete for space (Prentice 1988). Two exotic winter annuals, cheatgrass and storksbill, apparently are important interspecific competitors. Vigor of Allium aaseae populations can be reduced where these weeds are prolific (Prentice 1988). Livestock grazing on Allium aaseae is minimal, although indirect effects, such as habitat degradation and trampling are more serious. Deer have been observed feeding on Allium aaseae in early spring and chukars are known to eat bulbs later in the spring. The most serious insect pest seems to be an unknown seed predator that bores into and devours inner portions of the seed (Prentice 1988). A rust is common on populations in the Woods Gulch area, and maybe other places as well. The deep-seated bulb of Allium aaseae would survive wildfires. Hybridization and introgression are likely occurring between Allium aaseae and the more widespread A. simillimum (Smith 1995).
Terrestrial Habitat(s): Grassland/herbaceous, Shrubland/chaparral
Habitat Comments: Aase's onion is restricted to a narrow range of habitat conditions. It occurs on open, relatively barren, xeric, gentle to very steep, sandy slopes, generally with a southerly aspect, but ranging from east to west. It is usually associated with relatively sparsely vegetated bitterbrush (Purshia tridentata) or bitterbrush/sagebrush (Artemisia tridentata) communities. One or several bunchgrasses such as red threeawn (Aristida longiseta), bluebunch wheatgrass (Agropyron spicatum), squirreltail (Sitanion hystrix), needle-and-thread (Stipa comata), Sandberg's bluegrass (Poa sandbergii), Indian ricegrass (Oryzopsis hymenoides) and sand dropseed (Sporobolus cryptandrus) are often closely associated. Aase's onion sites are often bordered by Artemisia tridentata ssp. wyomingensis or ssp. tridentata/bunchgrass- dominated communities. Commonly associated species Eriophyllum lanatum, Balsamorhiza sagittata, Achillea millefolium, Phacelia heterophylla, and Eriogonum ovalifolium. A number of exotic species may be abundant, especially Bromus tectorum, Erodium cicutarium and Taeniatherum caput-medusae. Allium aaseae populations in the Boise Foothills often occur in close proximity to Astragalus mulfordiae, and/or Lepidium papilliferum, two other rare, regional endemic plants. These three rare species largely share the same conservation concerns and problems. On a local scale, Allium aaseae can be very common. At some sites it is one of the dominant forbs in early spring. When considering its sagebrush-bitterbrush/steppe and foothill grassland habitats rangewide, however, it is a minor constituent. Most populations are restricted to the alluvial soils of the Glenns Ferry Formation. This sandy substrate is of granitic origin and typically coarse textured, well-drained and relatively deep (Packard 1979; Prentice 1988). In the Boise Foothills, all populations occur on one of three sand-dominated geologic units - Pierce Gulch Formation Sand, Terteling Springs Formation Sand and Sandstone, and Terteling Springs Formation Sandy Sediments (Beck 1988). A large majority of Boise Foothill populations occur on three soil mapping units of Beck (1988): Quincy-Lankbush complex, Payette-Quincy complex, and Haw-Lankbush complex. Rarely, populations or portions of populations occur on other soil types, namely, Lankbush-Brent sand loam, Ada gravelly sand, and Searless-Rock outcrop complex. All known populations except for the two in Cartwright Canyon occur between 2700-4300 feet elevation, with the great majority below 3700 feet. Cartwright Canyon populations occur at 4950 and 5100 feet, and possibly indicate that soil characteristics such as texture are more important than elevation in determining the distribution of Allium aaseae (McNeal 1993).
Economic Attributes
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Economically Important Genus: Y
Economic Comments: Allium aaseae presently has no economic uses.
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 Author: Caicco, S.L., and E. Joyal
Element Ecology & Life History Edition Date: 29Feb1996
Element Ecology & Life History Author(s): M. Mancuso

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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  • Bolin, R., and R. Rosentreter. 1986. The autecology of Allium aaseae. Unpublished report. 12 pp.

  • Flora of North America Editorial Committee. 2002a. Flora of North America North of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. Oxford Univ. Press, New York. xxvi + 723 pp.

  • Hitchcock, C.L., A. Cronquist, M. Ownbey, and J.W. Thompson. 1969. Vascular plants of the Pacific Northwest. Part 1: Vascular cryptogams, gymnosperms, and monocotyledons. Univ. Washington Press, Seattle. 914 pp.

  • Holsinger, K. E. 1978. The role of selenium in the evolution of Allium aaseae Ownbey. Unpublished paper. 21 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.

  • Mancuso, M. 1995a. Draft conservation strategy for Allium aaseae Ownbey (Aase's onion). Conservation Data Center, Idaho Department of Fish and Game, Boise. 8 pp. plus appendices.

  • Mancuso, M. 1995b. Draft habitat conservation assessment for Allium aaseae Ownbey (Aase's onion). Conservation Data Center, Idaho Department of Fish and Game, Boise. 19 pp. plus appendices.

  • Mancuso, M., and R. K. Moseley. 1991. Field investigation of Allium aaseae (Aase's onion), on the Boise National Forest. Conservation Data Center, Idaho Department of Fish and Game, Boise. 14 pp. plus appendices.

  • McNeal, D. W. 1993. Taxonomy of Allium aaseae-Allium simillimum in Idaho. Unpublished report. 10 pp.

  • Moseley, R. K., and S. L. Caicco. 1989. Status and distribution of Aase's onion (Allium aaseae), a federal candidate species, on Ada County lands in Seaman Gulch. Unpublished report prepared for Ada County Solid Waste Management. Conservation Data Center, Idaho Department of Fish and Game, Boise. 6 pp. plus appendices.

  • Moseley, R.K., M. Mancuso, and J. Hilty. 1992. Rare plant and riparian inventory of the Boise Foothills, Ada County, Idaho. Unpublished report on file at Idaho Department of Fish and Game, Conservation Data Center, Boise, Idaho.

  • Packard, P. L. 1979. Status report for Allium aaseae. The College of Idaho, Caldwell. 11 pp.

  • Prentice, C. 1988. Progress report: a study of the life cycle of Allium aaseae Ownbey, Aase's onion. Coop agreement between Unimin Corporation and USDI Bureau of Land Management. 34 pp.

  • Prentice, C. 1989. 1989 Progress Report: A study of the life cycle of Allium aaseae Ownbey, Aase's onion. Cooperative Agreement between Unimin Corporation and USDI Bureau of Land Management, Boise, ID. 28 pp.

  • Smith, J. F. 1995. The genetic diversity of the rare Idaho endemic Allium aaseae Ownbey (alliaceae) and potential introgression with A. simillimum Henderson. Cooperative Challenge Cost Share Project, Bureau of Land Management, Boise District Office, and Boise State University, Biology Department. 186 pp.

  • U.S. Forest Service (USFS). No date. Idaho and Wyoming endangered and sensitive plant field guide. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Region. 192 pp.

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