Herzog salvinia
(Salvinia herzogii)
This species is a Cultivar and may be non-native across its range in the United States
ORIGIN: South America
GROWTH TRAITS: Giant salvinias consist of a group of very similar and closely related plants. They are aquatic, free-floating ferns that grow as annuals or short-lived perennials and have no true roots. Horizontal branching rhizomes float just below the surface and bear three leaves (fronds) at each node. Two leaves are floating, and one is submersed and divided into several filaments that resemble (but do not function as) roots. Floating leaves are oval-shaped and up to 1.6" (4 cm) long with smooth margins and distinct midribs. The water repellent white hairs on the upper surface of floating leaves have 4 branches that join back together at the tip, giving them an “egg beater” appearance. Hairs on the undersides of leaves and filaments are unbranched and chestnut-colored. Depending on nutrient and space availability, plants may be slender with small leaves or dense mats with large, crowded, folded leaves. Spore-producing structures (sporocarps) shaped like small eggs are arranged in chains on submersed filaments.
REPRODUCTION: Though sporocarps can be found on submersed filaments, these species are not known to produce fertile spores in the USA, and all reproduction occurs vegetatively via regular fragmentation of the rhizomes.
HABITAT: Giant salvinias grow best in still, shallow water with high organic content, and they often form dense mats. They do not tolerate saline environments.
LOOK-ALIKES: There are at least four exotic species known as giant salvinia present in the USA, of which S. molesta is the most common. Sporocarps are generally needed to tell them apart. The exotic and invasive common salvinia (Salvinia minima) is half the size of the giant salvinias, and its upper leaf hairs are free near the tips, while the upper leaf hairs of giant salvinias come together at the tips. Native mosquitoferns (Azolla spp.) may superficially resemble giant salvinias. Mosquitofern plants are much smaller, typically less than 1" (2.5 cm) wide, and have numerous tiny, overlapping leaves.
CITATIONS:
Rawlins, K.A., R.L. Winston, C.T. Bargeron, D.J. Moorhead, and R. Carroll. 2018. New Invaders of the Southeast. USDA Forest Service, Forest Health Assessment and Applied Sciences Team, Morgantown, West Virginia. FHTET-2017-05. Retrieved from http://bugwoodcloud.org/resource/pdf/FHTET-2017-05_New%20Invaders_SE.pdf
GROWTH TRAITS: Giant salvinias consist of a group of very similar and closely related plants. They are aquatic, free-floating ferns that grow as annuals or short-lived perennials and have no true roots. Horizontal branching rhizomes float just below the surface and bear three leaves (fronds) at each node. Two leaves are floating, and one is submersed and divided into several filaments that resemble (but do not function as) roots. Floating leaves are oval-shaped and up to 1.6" (4 cm) long with smooth margins and distinct midribs. The water repellent white hairs on the upper surface of floating leaves have 4 branches that join back together at the tip, giving them an “egg beater” appearance. Hairs on the undersides of leaves and filaments are unbranched and chestnut-colored. Depending on nutrient and space availability, plants may be slender with small leaves or dense mats with large, crowded, folded leaves. Spore-producing structures (sporocarps) shaped like small eggs are arranged in chains on submersed filaments.
REPRODUCTION: Though sporocarps can be found on submersed filaments, these species are not known to produce fertile spores in the USA, and all reproduction occurs vegetatively via regular fragmentation of the rhizomes.
HABITAT: Giant salvinias grow best in still, shallow water with high organic content, and they often form dense mats. They do not tolerate saline environments.
LOOK-ALIKES: There are at least four exotic species known as giant salvinia present in the USA, of which S. molesta is the most common. Sporocarps are generally needed to tell them apart. The exotic and invasive common salvinia (Salvinia minima) is half the size of the giant salvinias, and its upper leaf hairs are free near the tips, while the upper leaf hairs of giant salvinias come together at the tips. Native mosquitoferns (Azolla spp.) may superficially resemble giant salvinias. Mosquitofern plants are much smaller, typically less than 1" (2.5 cm) wide, and have numerous tiny, overlapping leaves.
CITATIONS:
Rawlins, K.A., R.L. Winston, C.T. Bargeron, D.J. Moorhead, and R. Carroll. 2018. New Invaders of the Southeast. USDA Forest Service, Forest Health Assessment and Applied Sciences Team, Morgantown, West Virginia. FHTET-2017-05. Retrieved from http://bugwoodcloud.org/resource/pdf/FHTET-2017-05_New%20Invaders_SE.pdf
Resources
- Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS
- Nonindigenous Aquatic Ferns in the United States - U.S. Geological Survey
Maps
State Lists - This map identifies those states that have this species on their invasive species list or law.
Invasive Listing Sources
- Federal Noxious Weeds
- Indiana Invasive Species Council - Invasive Plant List
- Indiana Pest Species
- Indiana Prohibited Plant Species
- Massachusetts Noxious Weeds
- Massachusetts Prohibited Plant List
- Michigan’s Prohibited and Restricted Species
- New Invaders of the Southeast
- South Carolina Illegal Aquatic Plants
- South Carolina Plant Pest List
- USDA APHIS Regulated Pest List
- Vermont Noxious Weeds
- Wisconsin Noxious Weeds
- Wisconsin's Invasive species rule – NR 40
Taxonomic Rank
| Domain: Eukarya |
| Kingdom: Plantae |
| Division: Pteridophyta |
| Class: Filicopsida |
| Order: Salviniales |
| Family: Salviniaceae |
| Genus: Salvinia |
| Salvinia herzogii |
References
Common Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.
Scientific Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.