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Montana Field Guide

Montana Field Guides

Large Flowered Beardtongue - Penstemon grandiflorus

Species of Concern
Native Species

Global Rank: G5?
State Rank: S1
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:

External Links

State Rank Reason (see State Rank above)
Rare in Montana, where it is known from only a few sites on the plains of eastern Montana.
General Description
Large Flowered Beardtongue is a stout perennial herb with 1-2 erect stems that are 5-10 dm tall and arising from a taproot surmounted by a woody, usually unbranched crown. The spoon- to egg-shaped basal leaves are 3-16 cm long and have petioles and entire margins. The opposite, clasping stem leaves are shorter and broadly oblong. Foliage is glabrous, thickish, and covered with a thin, bluish wax. The inflorescence consists of 3-7 clusters of 2-4 short-stalked flowers in the axils of the reduced upper leaves. The tubular corolla is flared and 2-lipped at the mouth, 35-48 mm long, and pink to lavender or pale blue. The 5 broadly lance-shaped calyx segments are 7-11 mm long and usually green throughout. The 4 anthers are glabrous.

Flowering and fruiting April-July.

Diagnostic Characteristics
The combination of exceptionally large flowers and glabrous inflorescence and anthers distinguish this species from others in Penstemon. It most closely resembles P. nitidus but the latter has a corolla less than 20 mm long. A hand lens may be required for identification.

Species Range

Range Comments
MT to IN, south to TX. One collection from Custer County; a collection from Phillips County represents a reclamation planting (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 5

(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)

Sandy soil of valleys on the plains.

Ecological Systems Associated with this Species

  • Additional ReferencesLegend:   View Online Publication
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    • Heidel, B. L. 1996. Noteworthy collections - Montana. Madrono 43(3):436-440.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Strickler, D. 1997. Northwest penstemons. Flower Press, Columbia Falls, Montana. 191 pages.
    • USDA, Agricultural Research Service. 1980. [Letter of December 3 to L. Dean Culwell containing the herbarium list for plant specimens on file at the Livestock and Range Research Station]. 13 pp.
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Citation for data on this website:
Large Flowered Beardtongue — Penstemon grandiflorus.  Montana Field Guide.  .  Retrieved on , from