Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

White Milkwort - Polygala alba

Native Species

Global Rank: G5
State Rank: S4
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
Polygala alba is common throughout eastern Montana. Plants grow in habitats that are widespread and relatively secure. Plant populations can vary from occasional to abundant; yet, threats or factors that may limit populations or its distribution have not been identified.
  • Details on Status Ranking and Review
    White Milkwort (Polygala alba) Conservation Status Review
    Review Date = 08/24/2020
    View State Conservation Rank Criteria
    Range Extent

    ScoreF - 20,000-200,000 sq km (~8,000-80,000 sq mi)

    Comment114,881 square kilometers.

    Area of Occupancy

    ScoreF - 126-500 4-km2 grid cells

    CommentMontana can be divided into 30,390 4x4 square kilometer cells. For this species 232 plant observations occur in 192 of these 4x4 square kilometer cells.

    Number of Populations

    ScoreD - 81 - 300

    Comment231 observations.

    Number of Occurrences or Percent Area with Good Viability / Ecological Integrity

    ScoreE - Many (41-125) occurrences with excellent or good viability or ecological integrity

    Comment53 observations described as "common", "abundant", "11-101 plants per plot", or "101-500 plants per plot".

    Environmental Specificity

    ScoreC - Moderate. Generalist or community with some key requirements scarce

    CommentPlants grow in grasslands and Ponderosa Pine woodlands.

General Description
PLANTS: Perennial plants that grow from a branched caudex. Stems are erect, singular, without hairs (glabrous), and 10–30 cm tall. Source: Lesica et al. 2012

LEAVES: Arranged in whorls or alternately on the stem. Leaf blades are simple with entire margin, linear to linear-oblanceolate in shape, without stipules, and 5–25 cm long. Source: Lesica et al. 2012

INFLORESCENCE: Spike-like and terminal. Flowers are white with a green center, contain both male and female organs (perfect), are irregular, and hypogynous. Sepals are 5 of which 2 are large and petal like while 3 are small. Petals are 3 and united below. Wing petals are 2-4 mm long. Lower petal is keel-shaped, 2-3 mm long with 4 lobes on each side. Stamens: 8. Ovary with a 2-lobed style. Fruit is a capsule. Source: Lesica et al. 2012

Diagnostic Characteristics
The flowers of Polygala can resemble papilionaceous flowers which are characteristic for members of the Pea (Fabaceae) Family. Montana has 2 Polygala species:

White Milkwort - Polygala alba, native and desirable
*Life Form: Perennial with a branched caudex.
*Leaves: Lower ones are alternate.

Whorled Milkwort - Polygala verticillata, native and desirable
*Life Form: Annual with a taproot.
*Leaves: Lower ones are whorled.

Species Range
Montana Range Range Descriptions


Range Comments
Washington to Minnesota south to Arizona, Texas and Mexico (Lesica et al. 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 336

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

In grasslands and ponderosa pine woodlands in the plains zone of Montana (Lesica et al. 2012).

Reproductive Characteristics
Plants reproduce by seed.

Capsule: ellipsoid, 2-celled (locules), and 2-3 mm long (Lesica et al. 2012). Seeds: 1 per cell and enclosed in an aril.

  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Anderson, N.L. 1951. Field studies on the biology of range grasshoppers of southeastern Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 96 p.
    • DuBois, K.L. 1979. An inventory of the avifauna in the Long Pines of Southeastern Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 113 p.
    • Fritzen, D.E. 1995. Ecology and behavior of Mule Deer on the Rosebud Coal Mine, Montana. Ph.D. Dissertation. Bozeman, MT: Montana State University. 143 p.
    • King, L.A. 1980. Effects of topsoiling and other reclamation practices on nonseeded species establishment on surface mined land at Colstrip, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 129 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
    • Meier, G.A. 1997. The colonization of Montana roadsides by native and exotic plants. M.Sc. Thesis. Bozeman, MT: Montana State University. 45 p.
    • Rennick, R.B. 1981. Effects of prescribed burning on mixed prairie vegetation in southeastern Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 144 p.
    • Seipel, T.F. 2006. Plant species diversity in the sagebrush steppe of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 87 p.
  • Web Search Engines for Articles on "White Milkwort"
Login Logout
Citation for data on this website:
White Milkwort — Polygala alba.  Montana Field Guide.  .  Retrieved on , from