Myriophyllum

Contains 5 accepted taxa overall.

Characteristics
Myriophyllum L.
HALORAGACEAE
WATERMILFOIL
View USF Herbarium specimens of this family
Classification
SAXIFRAGALES
Myriophyllum
Citation
MYRIOPHYLLUM Linnaeus, Sp. Pl. 992. 1753.
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TYPE: Myriophyllum spicatum Linnaeus Lectotypified by Britton & A. Brown, Ill. Fl. N. U.S., ed. 2. 2: 614. 1913.
Distribution Map Present

This species have been reported in the counties highlighted.

Species
Scientific Name Common Name Herbarium Specimens Status Photos
Myriophyllum aquaticum PARROT FEATHER WATERMILFOIL Not Native OBL (NWPL)
Myriophyllum heterophyllum TWOLEAF WATERMILFOIL Native OBL (NWPL)
Myriophyllum laxum LOOSE WATERMILFOIL Native OBL (NWPL)
Myriophyllum pinnatum CUTLEAF WATERMILFOIL Native OBL (NWPL)
Myriophyllum spicatum EURASIAN WATERMILFOIL; SPIKE WATERMILFOIL Not Native OBL (NWPL) Y
Identification Key
1.  Plants dioecious (only pistillate in North America); leafy stems mostly emersed; petiole 5-7 mm long; all leaves pectinate; emersed leaves mostly 2.5-3.5 cm long
M. aquaticum
1.  Plants monoecious, lower flowers pistillate, upper staminate; leafy stems mostly submersed; petiole <2 mm long; submersed leaves pectinate; emersed leaves pinnately divided, serrate, or bract-like, <2 cm long
2
2.  Leaves gray-green to dark green, strictly whorled, typically retaining their shape upon drying; stamens 8
M. spicatum
2.  Leaves green to reddish green, pseudowhorled to alternate (may appear whorled), typically collapsing and entangled upon drying; stamens 4
3
3.  Leaf division typically 12-28 per leaf; distal flowers whorled; fruit prominently beaked
M. heterophyllum
3.  Leaf divisions typically 8-16 per leaf; distal flowers alternate; fruit short-beaked
4
4.  Bracts 1-3 mm long, shorter than most inflorescence internodes, pectinate to entire; fruit surface smooth to papillose
M. laxum
4.  Bracts 4-10 mm long, subequal to longer than inflorescence internodes, pinnatifid to pectinate; fruit surface tuberculate
M. pinnatum
Genus Synonyms
Synonym Full Citation Basionym Type
Burshia Burshia Rafinesque, Med. Repos., ser. 2. 5: 357. 1808. TYPE: Burshia humilis Rafinesque
Enydria Enydria Vellozo, Fl. Flumin. 56. 1829 ("1825"), non Enydra Loureiro 1790. TYPE: Enydria aquatica Vellozo
Pelonastes Pelonastes Hooker f., London J. Bot. 6: 474 bis. 1847. TYPE: Pelonastes integrifolia Hooker f.
Pentapteris Pentapteris Haller, Hist. Stirp. Helv. 1: 424. 1768. TYPE: = Myriophyllum Linnaeus 1753.
Pentapterophyllon Pentapterophyllon Hill, Brit. Herb. 392. 1756.
Potamogeton Potamogeton Walter, Fl. Carol. 10, 90. 1788, non Linnaeus 1753. TYPE: Potamogeton verticollatus (Linnaeus) Walter 1788. (Myriophyllum verticillatum Linnaeus 1753.) Lectotypified by Z. Kaplan & Reveal, Brittonia 65: 466. 2013.
Ptilophyllum Ptilophyllum (Nuttall) Reichenbach, Deut. Bot. Herb.-Buch 169. 1841, non J. Morris 1840. BASIONYM: Myriophyllum Linnaeus, subg. Ptilophyllum Nuttall, Gen. N. Amer. Pl. 2: 211. 1818. TYPE: Myriophyllum ambiguum Nuttall
Sphondylastrum Sphondylastrum (Torrey & A. Gray) Reichenbach, Deut. Bot. Herb.-Buch 169. 1841. BASIONYM: Myriophyllum Linnaeus, sect. Spondylastrum Torrey & A. Gray, Fl. N. Amer. 1: 529. 1840. TYPE: Non designatus.
Vinkia Vinkia Meijden, Blumea 22: 251. 1975. TYPE: Vinkia callitrichoides (Orchard) Meijden (Myriophyllum callitrichoides Orchard)