Allium madidum

{{Short description|Species of flowering plant}}

{{Speciesbox

|name=Mountain swamp onion

| taxon = Allium madidum

| image =

| authority = S.Wats.

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Allium madidum, common name mountain swamp onion, is a plant species native to the west-central Idaho (Valley, Adams, and Washington Counties), southern Washington (Walla Walla County) and eastern Oregon. It grows in wet meadows at elevations of 1100–2000 m.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101373 Flora of North America v 26 p 255, Allium madidum][http://bonap.net/MapGallery/County/Allium%20madidum.png BONAP (Biota of North America Project), floristic synthesis Allium madidum]{{Cite web |url=http://www.wnps.org/cbasin/pdf/plant_lists/WallaWallaCounty.pdf |title=Vascular Plant List, Walla Walla County, Don Knoke, 2004, Washington Native Plant Society |access-date=2014-03-14 |archive-url=https://web.archive.org/web/20140314060102/http://www.wnps.org/cbasin/pdf/plant_lists/WallaWallaCounty.pdf |archive-date=2014-03-14 |url-status=dead }}

Allium madidum produces 1-3 bulbs with as many as 30 smaller bulbels attached. The full-size bulbs are round to egg-shaped, up to 1.6 cm long. Flowers are bell-shaped, up to 10 mm across; tepals white with green or pink midveins; pollen yellow.[https://www.biodiversitylibrary.org/page/8714521#page/238/mode/1up Sereno Watson. 1879. Proceedings of the American Academy of Arts and Sciences 14: 228.]Hitchcock, C. H., A.J. Cronquist, F. M. Ownbey & J. W. Thompson. 1969. Vascular Cryptogams, Gymnosperms, and Monocotyledons. 1: 1–914. In C. L. Hitchcock Vascular Plants of the Pacific Northwest. University of Washington Press, Seattle. Flowers bloom May to July.{{Cite web|title=Lady Bird Johnson Wildflower Center - The University of Texas at Austin|url=https://www.wildflower.org/plants/result.php?id_plant=ALMA6|access-date=|website=www.wildflower.org}}