Redroot Amaranth - Amaranthus retroflexus
(see State Rank Reason below)
MNPS Threat Rank
State Rank Reason (see State Rank above)
Native to parts of eastern and central North America and introduced into Montana. This is the most abundant pigweed in the state.
Monoecious. Stems erect, reddish below, 10–100 cm with sparsely pubescent foliage. Leaf blade lanceolate to ovate, 2–10 cm long, just longer than petiole. Inflorescence often red-tinged, dense, terminal and axillary panicles; bracts lanceolate-attenuate, 3–5 mm long, short-pointed. Flowers: sepals 5, ca. 3 mm long with blunt to rounded tips and excurrent midveins; stamens 4 to 5. Utricle ca. 2 mm, nearly as long as sepals (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
Known from nearly every MT county; throughout North America (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
- 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
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- Adhikari, S. 2018. Impacts of dryland farming systems on biodiversity, plant-insect interactions, and ecosystem services. Ph.D. Dissertation. Bozeman, MT: Montana State University. 207 p.
- Adhikari, S., L.A. Burkle, K.M. O'Neill, C.M. Delphia, D.K. Weaver, and F.D. Menalled. 2019. Dryland organic farming partially offsets negative effects of highly simplified agricultural landscapes on forbs, bees, and bee-flower networks. Environmental Entomology 48(4): 826-835.
- Eggers, M.J.S. 2005. Riparian vegetation of the Montana Yellowstone and cattle grazing impacts thereon. M.Sc. Thesis. Montana State University, Bozeman, MT. 125 p.
- Harvey, S.J. 1990. Responses of steppe plants to gradients of water soil texture and disturbance in Montana, U.S.A. Ph.D. Thesis. Bozeman, MT: Montana State University. 34 p.
- Jones, W. W. 1901. Preliminary flora of Gallatin County. M.S. Thesis. Bozeman, MT: Montana State College. 78 pp.
- Martinka, R.R. 1970. Structural characteristics and ecological relationships of male blue grouse (Dendragapus obscurus (Say)) territories in southwestern Montana. Ph.D Dissertation. Bozeman, MT: Montana State University. 73 p.
- Quire, R.L. 2013. The sagebrush steppe of Montana and southeastern Idaho shows evidence of high native plant diversity, stability, and resistance to the detrimental effects of nonnative plant species. M.Sc. Thesis. Bozeman, MT: Montana State University. 124 p.
- Seipel, T.F. 2006. Plant species diversity in the sagebrush steppe of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 87 p.
- Sirirugsa, P. 1973. Descriptive analysis of Montana species of Amaranthus. M.Sc. Thesis. Bozeman, MT: Montana State University. 56 p.
- Zapatka, T.P. 1963. Some results of two limited hunting seasons on hen Pheasants in north central Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 26 p.