twoleaf watermilfoil
Myriophyllum heterophyllum Michx.


Myriophyllum heterophyllum is a perennial, aquatic herb that has leaves of two noticeably different forms.
The submerged leaves are finely dissected, whorled, reddish/greenish-brown, and 0.5-2.5 in. (1.3-6.4 cm) long. The emergent leaves are small, oval, bright green, whorled and up to 0.25 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.
Ecological Threat
Myriophyllum heterophyllum 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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EDDMapS Distribution

EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit

State Regulated List

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Rosidae
Order: Haloragales
Family: Haloragaceae
Genus: Myriophyllum
Subject: Myriophyllum heterophyllum Michx.

Synonyms and Other Names

Other Common Names:
twoleaf watermilfoil, broadleaf water-milfoil, variable watermilfoil


Plants - Aquatic Plants