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Astragalus bibullatus (Limestone glade milkvetch)
Wallace, George

Astragalus bibullatus

Astragalus bibullatus Barneby & Bridges

Limestone Glade Milkvetch, Pyne's Ground-plum, Guthrie's Ground-plum

Fabaceae (Pea Family)


USDA Symbol: ASBI6

USDA Native Status: L48 (N)

An herbaceous perennial to about 6 inches in height. Roots: tap-rooted. Stems and leaves: essentially glabrous with scattered, fine appressed hairs.. Leaves: 5 to 10, once pinnate, petiole about 3/4 inch in length; often with one or a pair of leaf-like, membranous, sheath-forming stipules subtending. Leaflets: 19 to 27 per leaf, elliptic-obovate. Inflorescence: a raceme bearing 10 to 16 flowers. Flowers: zygomorphic, light pinkish-purple, borne on an upward-arching peduncle during anthesis. Fruit: A fleshy pod; red above and yellow below at maturity; borne on downward-arching peduncles. Flowers: April-May. Fruits: May-June.

Federally-listed endangered species since 1991. State-listed Endangered species in TN. Resembles Astragalus tennesseensis with which its populations sometimes mingle. Once considered a disjunct population of the Midwestern species, Astragalus crassicarpus which it also closely resembles.


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Plant Characteristics

Duration: Perennial
Habit: Herb
Root Type: Tap
Leaf Complexity: Pinnate
Breeding System: Flowers Bisexual
Inflorescence: Raceme
Fruit Type: Legume
Size Notes: To about 6 inches in height.
Leaf: Once-compound.
Flower: Flower color is light, pinkish-purple. Likely pollinated by insects, but pollinators are undetermined.
Fruit: Bladdery and inflated, resembling a plum. Single plants may bear as many as 50 fruits.

Bloom Information

Bloom Color: Pink , Purple
Bloom Time: Apr , May


Native Distribution: Endemic to Rutherford County, Tennessee. Historically, it was known to also occur in adjacent Davidson County in an area now deluged by the J. Percy Priest Reservoir.
Native Habitat: Limestone cedar glades in the Tennessee Central Basin Section of the Interior Low Plateau.

Growing Conditions

Water Use: Medium
Light Requirement: Sun
Soil Moisture: Moist
Soil pH: Alkaline (pH>7.2)
CaCO3 Tolerance: High
Drought Tolerance: Medium
Cold Tolerant: yes
Heat Tolerant: yes
Soil Description: Thin (3 to 12 inches), calcareous soils of Gladeville and Talbott series on karst limestone bedrock supporting little vegetation.
Conditions Comments: Habitat is wet and cold in winter, dry and hot in summer. Terrain is generally flat. Plants grow in crevices in the bedrock between large flagstones.


Conspicuous Flowers: yes

U.S. Fish & Wildlife Service Threatened & Endangered Status

USFWS Species Profile: Q2Z8
Status: Endangered
Historic Range: U.S.A. (TN)
Critical Habitat: N/A
Special Rules: N/A
This information is derived from the U.S. Fish & Wildlife Serrvice Environmental Conservation Online System.

Additional resources

USDA: Find Astragalus bibullatus in USDA Plants
FNA: Find Astragalus bibullatus in the Flora of North America (if available)
Google: Search Google for Astragalus bibullatus


Record Modified: 2019-02-21
Research By: Joseph A. Marcus

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