Egeria, Anacharis (Egeria densa) Planch.
Egeria, Anacharis (Egeria densa) Planch.
Egeria was sold as a rapid growing and attractive oxygenator plant for ponds and aquaria as long ago as 1915 (Countryman 1970). It remains one of the most universally used and distributed aquarium plants. Oxygenator plants were also widely used to control mosquito larvae. Cook and Urmi-Konig (1984) speculated that egeria was planted for malaria eradication. It is widespread in the United States; the most abundant populations appear in the eastern states between latitudes 33 N and 35 N (Cook and Urmi-Konig 1984). In 1990, 22 populations were detected in Florida public waters where it covered 37 ha. Egeria ranked 83rd in abundance of all aquatic plants (Schardt and Schmitz 1990).
In its home range, egeria prefers quiet or slowly moving, shallow waters that are somewhat acidic and enriched. It is less tolerant of high temperatures than hydrilla, and its preferred range is 16-18 C (Barko et al. 1980). In Florida, egeria is most abundant in rivers and springs, perhaps because temperatures remain within egeria's tolerance limits throughout most of the year (Schardt and Schmitz 1990). In some water bodies, egeria is a nuisance.
Vegetative fragments, particularly those with double nodes, readily root and develop new shoots (Getsinger and Dillon 1984). Egeria is a buoyant plant, and most of its biomass is produced near the water surface where the plant can interfere with human activities; however, egeria only occasionally causes problems in Florida waters (Schardt and Schmitz 1990). Problematic populations are usually controlled with herbicides or occasionally with sterile grass carp. Egeria is not preferred but is readily consumed by grass carp; however, rivers and spring runs are usually not appropriate release sites for herbivorous fishes. Herbicides for the control of egeria include diquat and copper and are only marginally successful in flowing water, and therefore the plants are usually left alone or harvested (Schardt and Schmitz 1990).
