Family: Hydrocharitaceae (Tape-Grass Family)
Duration and Habit: Perennial Herb
A rhizomatous, perennial, submerged aquatic plant. It has numerous threadlike roots, which are 'adventitious' (branching from the stem) and, along with rhizomes (horizontal stems in the sediment), anchor it to the bottom. Stems, which can reach the surface, are brittle and sparsely branched, 3-5mm in diameter and curved towards the base (J-shaped). The leaves are 5-20mm long and 2-3mm wide, and occur in alternate spirals along the stem. They generally have tapered tips curving downwards towards the stem, except in low alkalinity water where they are straight. The three-petalled female flowers are very small, clear-white on the surface, and grow on very thin white to almost translucent 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: Lagarosiphon major is fast-growing, may totally fill the volume of a large shallow lake (to 3 m deep, fills water control channels, in New Zealand, Lagarosiphon major is a major aquatic weed problem recorded in many lakes,
Biology & Spread:
U.S. Habitat: lakes, riparian zones, water courses, wetlands
U.S. Nativity: Cultivated, or not in the U.S.
Native Origin: Native in southern Africa
U.S. Present: Happily, Lagarosiphon major does not yet occur in the wild in the United States, as 2008, so far as is known. However, experts have reason to believe that should this plant be introduced to the U.S., the resulting problems could be as consequential as those caused by another plant in the Hydrocharitaceae family, hydrilla (Hydrilla verticillata)
Distribution: Under favourable 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)
Center for Aquatic Invasive Plants. 2009. African elodea. University of Florida. Accessed 19 August 2010 (http://plants.ifas.ufl.edu/node/220).
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