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Montana Field Guide

Montana Field Guides

Flower-of-an-Hour - Hibiscus trionum
Other Names:  Venice Mallow, Bladder Hibiscus

Non-native Species

Global Rank: GNR
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 1

External Links

General Description
Hirsute annual. Stems erect, branched, 10–60 cm. Leaf blades orbicular, divided nearly to the base; lobes 3 to 7, 1–4 cm long. Flowers axillary, subtened by linear bracts; calyx veiny, inflated, 8–14 mm long, with short, acute lobes; petals whitish with a purple base,15–40 mm long. Schizocarp 1–3 cm high, hirsute with 5 sections (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Montana Range


Range Comments
SK to NS south to OR, UT, TX, FL; introduced from Europe (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 23

(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)


The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus pensylvanicus and Bombus griseocollis (Colla and Dumesh 2010).


  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141: 39-68.
    • 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.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Web Search Engines for Articles on "Flower-of-an-Hour"
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Citation for data on this website:
Flower-of-an-Hour — Hibiscus trionum.  Montana Field Guide.  .  Retrieved on , from