| variable watermilfoil |
USDA PLANTS Symbol: MYHE2 USDA ARS GRIN: 400095 ITIS: 27044 NAPIS: PCDABBC |
| Myriophyllum heterophyllum Michx. | |
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Taxonomic Rank: Magnoliopsida: Haloragales: Haloragaceae |
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| Synonym(s): twoleaf watermilfoil, broadleaf water-milfoil | |
Variable watermilfoil is a perennial, aquatic herb that has leaves of two noticeably different forms. The submerged leaves are finely dissected, whorled, reddish/greenish-brown, and ½-2 ½ in. (1.3-6.4 cm) long. The emergent leaves are small, oval, bright green, whorled and up to ¼ in. (0.6 cm) wide. Emergent leaves stand 6-8 in. (15.2-20.3 cm) out of the water and may not be apparent until late summer. Flowering occurs from June to September. Flowers are emergent on 2-12 in. (5.1-30.5 cm), green to reddish stalks. Petals are less than 0.1 in. (3 mm) in length and are subtended by downward curved bracts. Fruits are small, nearly round and have a rough surface. Variable watermilfoil is native to the southern United States, but is considered invasive in much of the northeast. This species is listed as endangered or threatened in three states (Kentucky, Ohio, and Pennsylvania). |
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Identification, Biology, Control and Management Resources
- Invasive Plant Atlas of New England - University of Connecticut
| Selected Images from Invasive.org | View All Images at Invasive.org |
 Foliage; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org Additional Resolutions & Image Usage |
 Diagram or Graphic; USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service. USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage |
 Diagram or Graphic; Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 616. USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage |
Taxonomic References:
- USDA, NRCS. 2001. The PLANTS Database, Version 3.1, National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Invasive Listing Sources:
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