Hydrilla verticillata
waterthyme
Family
Hydrocharitaceae
Leaf Arrangement
whorled
Leaf Attachment
sessile
Leaf Margin
toothed
Growth Form
submerged aquatic, aquatic
Milky Sap
No
Armed/Unarmed
Unarmed
Origin
introduced
Lifespan
perennial
Growing Season
Warm season
Wetland Class
OBL
Field Characters
2-8 leaves in a whorl around stem. Spined teeth along the leaf margins and a red midvein when fresh. May be confused with Elodea canadensis which have only 3 leaves in a whorl and a green midvein. Off-white to yellowish rhizomes.
Cultural Information
Reproduces mainly by regrowth of stem fragments; also reproduces by growth of axillary buds(turions) and subterranean tubers; tubers can remain viable for more than 4 years. A single tuber can grow to produce more than 6,000 new tubers per m2.
Natural History
Invasive aquatic species on the Federal noxious species list.