Plains Phlox - Phlox andicola
State Rank Reason (see State Rank above)
Plains phlox reaches the western margin of its range in Montana's eastern counties. It has been documented from relatively few locations, but surveys during its early blooming season have been few, and additional spring inventory work may locate more populations. It likely tolerates grazing and may benefit from some level of disturbance.
- Details on Status Ranking and Review
Score1 - Moderate: Generally 10,000-100,000 individuals.
Score0-1 - Widespread to Sporadically Distributed: Species has a distribution in the state such that it is borderline in its classification or its distribution is too imprecisely documented to place it in one class.
Area of Occupancy
Score1-2 - Low to Moderate. Occurs in 4-25 Subwatersheds (6th Code HUC’s), though the species' distribution is not sufficiently documented to place it within one class.
Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).
CommentGenerally limited to sandy soils.
ScoreNA - Rank factor not assessed.
Score0-1 - Low to Medium.
CommentNo specific threats have been identified.
Score0 - Low Vulnerability: Species does not have any unusual or specific life history or biological attributes or limted reproductive potential which makes it susceptible to extirpation from stochastic events or other adverse impacts to its habitat and thus slow to recover.
Raw Conservation Status Score
3 to 6 total points scored out of a possible 16 (Rarity factors and threats only).
Plains Phlox is a perennial herb with loosely tufted stems that are 4-10 cm high arising from creeping rhizomes. The 5-8 pairs of opposite, linear leaves have prominent midveins and whitish bases and are 10-25 mm long, ca. 1 mm wide and come to a sharp point. Foliage is glabrous to sparsely hairy. Stems are white. 1-5 white flowers are borne at the stem tips. Each flower has 5 petals and a tubular corolla. The calyx is also tubular, with 5 lobes, tangled long hairs, and 6-11 mm length.
Flowering occurs in May and early June.
Phlox hoodii and P. bryoides have shorter leaves, only 1 flower per stem, and shorter corolla lobes (3-5 mm). Leaves of P. alyssifolia are 2-5 mm wide, and the calyx tube is equal to the lobes. Dimensions of the largest P. hoodii plants may overlap with those of the smallest P. andicola. Flowers are needed for positive identification, and hybridization has been reported among these species (Great Plains Flora Association 1986).
Great Plains, from ND to MT, south from KS to CO. Peripheral.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Plains phlox occupies a wide range of habitats in the center of its range, including sparsely vegetated outcrops, sandplains, and heavy alkaline clays (Barr 1983). In Montana, it is known mainly from sandy soils in grasslands and ponderosa pine woodland, often associated with sparsely vegetated erosional blowouts and loose sand below sandstone outcrops. Dominants in this habitat include Stipa comata, Bouteloua gracilis, Agropyron smithii, Carex heliophila, and C. filifolia. Associated species in Sheridan and Carter counties include Psoralea argophylla, P. lanceolata, Calamovilfa longifolia, Andropogon scoparius, Artemisia ludoviciana, A. frigida, Rhus trilobata, Poa sandbergii and Opuntia polyacantha.
Given the large size of some Montana populations of plains phlox, its distribution across at least four counties, and its close resemblance to Phlox hoodii, it seems likely that Phlox andicola is more widespread than current records suggest. It is characterized as "frequent on dry prairies and plains in western South Dakota" (Van Bruggen 1985), and early-season surveys will likely provide additional Montana records for this species.
Ecological Systems Associated with this Species
Plains phlox is long-lived, with very deep, woody roots (Barr 1983). Prairie phlox species can reproduce by rhizomes as well as by seeds, and are generally adapted to insect-pollination. This species occupies sparsely vegetated, mid-successional habitats, and is one of several sand-loving Species of Concern often found where the habitat is extensive and/or in good condition.
Montana populations are in sparsely vegetated habitats that receive little use by livestock, and the low growing form of Phlox andicola makes it resistant to browsing. The species appears to be adapted to small-scale disturbance, and its habitat may be fostered by management that involves some disturbance. One of the larger populations documented was in a calving pasture. Another survey reported it to be particularly vigorous in burned areas.
- Additional ReferencesLegend: View Online Publication
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- Barr, C.A. 1983. Jewels of the Plains. University of Minnesota Press, Minneapolis, Minnesota. 236 pp.
- Great Plains Flora Association (McGregor, R.L., coordinator, and T.M. Barkley, R.E. Brooks, and E.K. Schofield - eds.). 1986. Flora of the Great Plains. Lawrence, KS: Univ. Press Kansas. 1392 pp.
- Heidel, B.L. 1994. Sensitive plant species survey in Garfield and McCone Counties, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, Montana. 58 pp. plus appendices.
- Heidel, B.L. and K.H. Dueholm. 1995. Sensitive plant survey in the Sioux District, Custer National Forest, 1994, Carter County, Montana and Harding County, South Dakota. Unpublished report to the Custer National Forest. Montana Natural Heritage Program, Helena, Montana. 95 pp. plus appendices.
- Heidel, B.L., S.V. Cooper and C. Jean. 2000. Plant species of special concern and plant associations of Sheridan County, Montana. Report to U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, Montana. 96 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Van Bruggen, T. 1985. The vascular plants of South Dakota, 2nd ed. Iowa State University Press, Ames, Iowa. 476 pp.
- Vanderhorst, J.P., S.V. Cooper, and B.L. Heidel. 1998. Botanical and vegetation survey of Carter County, Montana. Unpublished report prepared for the Bureau of Land Management. Montana Natural Heritage Program, Helena. 116 pp. + app.