Nuphar microphylla is a perennial, rhizomatous, aquaticNuphar microphylla (Pers.) Fernald. (n.d.). Plants of the World Online. Retrieved January 30, 2025, from https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A171086-2 herb found in North America. It is listed as a special concern and believed extirpated in Connecticut."Connecticut's Endangered, Threatened and Special Concern Species 2015". State of Connecticut Department of Energy and Environmental Protection Bureau of Natural Resources. Retrieved 17 January 2018. (Note: This list is newer than the one used by plants.usda.gov and is more up-to-date.)
Description Vegetative characteristics Nuphar microphylla is a perennial,Wisconsin State Herbarium, UW-Madison. (n.d.). Nuphar microphylla (Pers.) Fernald. Flora of Wisconsin. Retrieved January 30, 2025, from https://wisflora.herbarium.wisc.edu/taxa/index.php?taxon=4338 rhizomatous, aquatic herb with 1–2 cm wide rhizomes.Nuphar microphylla in Flora of North America @ efloras.org. (n.d.). Retrieved January 30, 2025, from http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500815 The ovate to broadly elliptic, 3.5–10(–13) cm long, and 3.5–7.5(–8.5) cm wide floating leaves have a deep sinus. The abaxial leaf surface is often purple.Perron, M. (n.d.). Small yellow pond-lily Nuphar microphylla Petit nénuphar jaune. Flore Du Québec. Retrieved January 30, 2025, from http://floreduquebec.ca/english/nuphar%20microphyllaPA Department of Conservation and Natural Resources. (n.d.). Nuphar microphylla Yellow Cowlily. Pennsylvania Natural Heritage Program (PNHP). Retrieved January 30, 2025, from https://www.naturalheritage.state.pa.us/factsheet.aspx?=14187 The leaf venation is pinnate.Massachusetts Division of Fisheries & Wildlife. (2015). Tiny Cow-lily Nuphar microphylla (Pers.) Fern. In Natural Heritage & Endangered Species Program. Retrieved January 30, 2025, from https://www.mass.gov/doc/tiny-cow-lily/download
Generative characteristics The small, yellow to green, 1–2 cm wide flowers float on the water surface. The red stigmatic disks are 2.5–7 mm wide.
Cytology The chromosome count is 2n = 34.
Taxonomy It was first published as Nymphaea microphylla by Christiaan Hendrik Persoon in 1806.Persoon, C. H. (1805). Synopsis plantarum, seu Enchiridium botanicum, complectens enumerationem systematicam specierum hucusque cognitarum (Vol. 2, p. 63). C.F. Cramerum. https://www.biodiversitylibrary.org/page/235397Nymphaea microphylla Pers. (n.d.). International Plant Names Index. Retrieved January 30, 2025, from https://www.ipni.org/n/605628-1 It was placed into the genus Nuphar as Nuphar microphylla published by Merritt Lyndon Fernald in 1917.Fernald, Merritt Lyndon. (1917). A Diagnostic Character of Nuphar microphyllum. Rhodora, 19, 111--111. https://www.biodiversitylibrary.org/part/188288 It is placed in the section Nuphar sect. Nuphar.Nuphar microphylla (Persoon) Fernald. (n.d.). Database of Vascular Plants of Canada (VASCAN). Retrieved January 30, 2025, from https://data.canadensys.net/vascan/taxon/6713 It is a parent species of the natural hybrid Nuphar × rubrodisca
Etymology The specific epithet microphylla means small-leaved.Mifsud, S. (n.d.). Micromeria microphylla (Maltese savory). MaltaWildPlants.com - the Online Flora of the Maltese Islands. Retrieved January 30, 2025, from https://www.maltawildplants.com/LABT/Micromeria_microphylla.phpPilea microphylla. (n.d.). Missouri Botanical Garden. Retrieved January 30, 2025, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b614
Ecology Habitat It occurs in ponds, marshes, and lakes.University of Michigan Herbarium. (n.d.). Nuphar microphylla (Pers.) Fernald. Michigan Flora. Retrieved January 30, 2025, from https://michiganflora.net/record/1727
Conservation It is endangered in the US-american states Pennsylvania, Michigan, Massachusetts, and New Hampshire.Native Plant Trust. (n.d.). Nuphar microphylla — small-leaved pond-lily. Native Plant Trust Go Botany. Retrieved January 30, 2025, from https://gobotany.nativeplanttrust.org/species/nuphar/microphylla/ It is susceptible to pollution,Michigan State University. (n.d.). Nuphar microphylla (Small yellow pond lily). Michigan Natural Features Inventory. Retrieved January 30, 2025, from https://mnfi.anr.msu.edu/species/description/14438/Nuphar-microphylla e.g., by herbicides meant to combat invasive weeds. It is also threatened by invasive plants.
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