BugwoodWiki Article

twoleaf watermilfoil
Myriophyllum heterophyllum Michx.

Overview

Appearance
Myriophyllum heterophyllum is a perennial, aquatic herb that has leaves of two noticeably different forms.
Foliage
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.
Flowers
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.
Fruit
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).

Resources

Selected Images


5273020
5273020

twoleaf watermilfoil
Myriophyllum heterophyllum
Infestation
Leslie J. Mehrhoff
5273021
5273021

twoleaf watermilfoil
Myriophyllum heterophyllum
Foliage
Leslie J. Mehrhoff
5308025
5308025

twoleaf watermilfoil
Myriophyllum heterophyllum
Plant(s)
USDA PLANTS Database
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5308026

twoleaf watermilfoil
Myriophyllum heterophyllum
Plant(s)
USDA PLANTS Database

Maps


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 www.eddmaps.org

EDDMapS Distribution

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

State Regulated List

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Rosidae
Order: Haloragales
Family: Haloragaceae
Genus: Myriophyllum

Other System Links

Plants: MYHE2
Bayer: MYPHE
GRIN: 400095
ITIS: 27044
NPDN Pest: PCDABBC

Synonyms and Other Names

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

Categories

Category: Aquatic
Category: Forbs/Herbs