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Federal Noxious Weed TDA Noxious Weed TPWD Prohibited Exotic Species Invasive Plant Atlas of the USNOTE:
means species is on that list.
Lagarosiphon major
Oxygen-weed
Synonym(s):
Family: Hydrocharitaceae (Tape-Grass Family)
Duration and Habit: Perennial Herb
Photographer: Rohan Wells
Source: National Institute of Water & Atmospheric Research, Bugwood.org
Description
Lagarosiphon major is a perennial, submerged, aquatic plant. It has many thread-like roots, which are 'adventitious' (branching from the stem) and, along with rhizomes (horizontal stems in the sediment), anchor it to the bottom. Stems that can reach the surface, are brittle and sparsely branched, 3-5mm in diameter and J-shaped. The leaves are 5-20mm long and 2-3mm wide, and occur in alternate spirals along the stem.The female flowers are 3-petaled, very small, clear-white on the surface, and grow on very thin, whitish, filament-like stalks.
Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Oxygen-weed.
Ecological Threat: The English common name 'oxygen weed' refers to the species ability to 'oxygenate' the water, however, the dense mats of vegetation that are characteristic of this species when introduced outside of its native range actually decrease the oxygen levels by limiting water circulation and increasing decomposition.
Lagarosiphon major is fast-growing, may totally fill the volume of a large shallow lake (to 3 m deep, fills water control channels.
Biology & Spread: Lagarosiphon major is very difficult to control, and its ability to form new plants vegetatively facilitates its spread to new locations. The trade and potential escape of L. major through the aquarium and water garden industry plays a large role in its spread to new locations, as does the transportation of this plant on recreational equipment moving between water bodies (Cronk and Fuller, 1995). Other species of the family Hydrocharitaceae also have the potential to become invasive, and Elodea canadensis, Egeria densa, and Hydrilla verticillata, have been recorded as problematic outside of their native range.
History: Not introduced to the United States. Declared as a Federal Noxious Weed in 2006. Spread through the world by the aquarium trade.
U.S. Habitat: lakes, riparian zones, water courses, wetlands
Distribution
U.S. Nativity: Not in the U.S.
Native Origin: Native in southern Africa
U.S. Present: As of 2023, Lagarosiphon major does not yet occur in the wild in the United States; partly due to Early Detection efforts at a Federal and State level. However, experts believe should this plant be introduced to the U.S., the resulting problems could be as consequential as hydrilla (Hydrilla verticillata) an infamous invasive also in the Hydrocharitaceae family.
Distribution in Texas: Under favorable conditions, dense growth of the plant can block light penetration into waterways, eliminating growth of native water plants and affecting associated populations of aquatic invertebrates and vertebrates. Once widespread, control would be extremely difficult (as is the case for most submerged aquatics)
Mapping
Invaders of Texas Map: Lagarosiphon major
EDDMapS: Lagarosiphon major
USDA Plants Texas County Map: Lagarosiphon major
Native Alternatives
Management
USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.Text References
Center for Aquatic Invasive Plants. 2009. African elodea. University of Florida. Accessed 19 August 2010 (http://plants.ifas.ufl.edu/node/220).
Bickel, T.O. 2011. Lagarosiphon major (Ridley) Moss ex Wager (Curly Water Weed). In: Francis, R.A. (Ed.). A Handbook of Global Freshwater Invasive Species (1st ed.). Routledge.
Online Resources
https://www.invasivespeciesinfo.gov/aquatic/plants/oxygen-weed
Search Online
Google Search: Lagarosiphon major
Google Images: Lagarosiphon major
NatureServe Explorer: Lagarosiphon major
USDA Plants: Lagarosiphon major
Invasive Plant Atlas of the United States: Lagarosiphon major
Bugwood Network Images: Lagarosiphon major
