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 Add this item to the list  Salvinia molesta
    

Illustrations

 Illustrations :
Salvinia_molesta_3512-a.jpg
Salvinia_molesta_3512-b-2.jpg
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Salvinia_molesta_DSC_1480.jpg
Salvinia_molesta_IMG_0008.jpg
 

Taxonomy

 Family :Salviniaceae 
 Genus :Salvinia 
 Epitheton :molesta 
 Author(s) :Mitch. 
 Rank :species 
 Factsheet link (English) :
 
 Factsheet link (French) :
 
 Factsheet link (Dutch) :
 

Morphology

 
Overall
 Height of plant (m) :0 - 0.003 
 
Roots and stem
 Description of subterranean parts :roots absent. 
 Description of stem :horizontal floating, slender, irregularly branched, pubescent. 
 
Propagules
 Description of propagule :reproduction is exclusively vegetative by (rapid) growth and fragmentation. 
 Description of seedling :species in the S. auriculata complex progress through 3 phenotypes or grow stages, controlled by age, degree of crowding, water turbulence, and other abiotic factors. Primary Juvenile Phase: leaves small (± 10 mm in diameter) and lie flat on the water surface (survival stage, where nutrient conditions are low). Second Growth Phase: Leaves grow to ± 25 mm in diameter and begin to fold upward, giving the structure a keeled shape (colonizing stage). Tertiary Growth Phase: leaves ± 38 mm wide and 25 long. The terminal bud now forms leaves which are compact, almost vertical, and acute folded. (mat stage). 
 
Leaf
 Description of leaf :the 2 upper leaves are floating, photosynthetic, entire, elliptic-ovate to rounded, with a distinct midvein, covered with papillae, apices rounded or emarginate and the submerged leaf is finely divided into linear segments (feathery), segments appearing as and functioning as roots. Leaves are mat-forming, mat to 2.5 cm thick (or much thicker, depending on local conditions such as water current, waves, etc. Papillae either fairly uniform in size throughout, or inner longer than outer; papillae apex split into several, more celled hairs that form a birdcage-like structure; the cage traps an air bubble when submerged, creating a non-wetting upper surface. Lower leaves submerged, subsessile or petiolate, with or without sporocarps. 
 Length of petiole (cm) :0 - 3 
 
Flower
 Description of inflorescence :Sporocarps sessile or stalked on 2—4 long axes, ca 1 mm diameter, ovoid, apiculate, consisting of either numerous long stalked microsporangia, or a few short-stalked macrosporangia, or a few short-stalked macrosporangia, but most often spores are not formed. 

Additional information

 Uses :the rapid growing plant appears to have some potential in wastewater purification while the plant is very efficient in removing heavy metals and nutrients (for example nitrogen and phosphorus) from water. It can be used to produce methane for biogas by anaerobic digestion. Other potential uses include utilization as a compost and mulch, and as a supplement to livestock feed. However, it is not suitable as a sole source of fodder because of the high content of crude ash and tannins that reduce digestibility. 
 Similar species :because other species without the auriculata complex have papillae with hairs not jointed to form a bird cage-like structure Salvinia natans can be easily recognized! Within the Salvinia auriculata complex, all species are vegetatively similar. Therefore reproductive structures should be used for identifying species within the complex whenever possible. S. molesta (a. Upper leaves: with papillae of approximative equal size in outer 1/3 of leaf; those of outer 1/3 at most 2x as long as wide; those of the inner 2/3 considerably longer than wide. b. Papillae: 5-10 in number from margin to midrib. c. Lower leaves: petiolate, divided distally with short branches not recurved. d. Sporocarp: globose to apiculate, sessile to short-stalked, stalks arranged in a racemose manner along the fertile axis.) S. auriculata (a. Upper leaves: with papillae of approximative equal length in outer 2/3 of leaf; those of outer 1/3 at most as long as wide. b. Papillae: 10-26 in number from margin to midrib. c. Lower leaves: sessile or long petiolate, divided distally with short recurved branches. d. Sporocarps: globose, log-stalked, stalks mostly attached at the apex of submerged leaves; usually <14 in number.) 

Distribution information

 Original distribution :South-eastern Brazil. 
 Current distribution :Asia: India, Indonesia, Malaysia, Philippines, Singapore, Sri Lanka, Thailand. Africa: Benin, Botswana, Cameroon, Congo, Congo Democratic Republic, Côte d'Ivoire, Ghana, Kenya, Lesotho, Malawi, Mozambique, Namibia, Nigeria, South Africa, Swaziland, Tanzania, Uganda, Zambia, Zimbabwe. Europe: Italy. North America: USA. Central America: Cuba, Trinidad and Tobago. South America: Argentina, Brazil, Colombia, Guyana. Oceania: Australia, Fiji, French Polynesia, New Caledonia, New Zealand, Papua New Guinea, Tasmania, Vanuatu. 
 Distribution :
Salvinia_molesta.gif
Salvinia_molesta.gif
 

Biochemistry and molecular data

 Ploidy :n = 45 (Louyal & Grewal, 1966 [as S. auriculata Aubl.]; Mitchell, 1972), pentaploid? The high proportion of sporangia abortion indicates that this taxon could be of hybrid origin (possibly of S. biloba Raddi and S. auriculata Aubl.). 

Ecology

 
Life cycle :
annual variable
perennial variable
monocarp no
 
 
 Competitiveness :Thick mats of Salvinia cut of light to submerged plants, thereby depressing oxygen concentrations, and increasing levels of carbon dioxide and hydrogen sulphide in waters beneath them. 
 Hardiness :Salvinia is killed when its buds are exposed to temperatures below -3ºC, but leaves can survive freezing air temperatures if the are under the water surface. 
 Habitat requirements :it tolerates very little drying (it can survive for a short time on mud banks). The plant has a low tolerance of salinity, but grows in a wide range of nutrient levels. Optimum growth occurs in nutrient-rich situations at pH 6-7.7, with water temperatures between 20-30ºC, particularly when the nitrogen source is the ammonium ion (NH4)+ rather tan the nitrate ion. Growth is enhanced by high light intensities, relatively high water temperatures, and plenty of nutrients. Water temperature rising to 30ºC results in elevated growth rates, as do increasing the concentrations of nutrients, especially nitrogen and phosphorus. Thus, eutropic habitats such as nutrient-rich springs and phosphate mine reclamation wetlands and ponds would particularly suitable for rapid colonization and growth. 
 Ecological amplitude :S. molesta colonizes disturbed habitats including rice paddies, flood canals, artificial lakes and hydro-electric facilities. It occurs most commonly in fresh water lakes, streams, ditches and water tanks. It grows best in stagnant or slow moving water and prefers small bays in inlets of dissected shorelines and tributaries of small streams. Growing around emergent brush and trees on flooded shorelines, it is protected from wave action and multiplies rapidly. 
 Habitat elsewhere :in its native range, S. occurs in artificial reservoirs, swamps, drainage channels, and along margins of rivers. 
 Palatability :the species provides food for some fishes and is eaten by ducks, geese, swans, pigs, and sometimes by cattle, deer, and upland game birds. 

Invasiveness, risk and control

 
Dispersal mechanism :
wind variable
water variable
 
ectozoochorous variable
others variable
 
 Host, diseases and pest information :mainly in rice paddies. Herbivors: Cyrtobagous salvaniae and Cyrtobagous singularis (Coleoptera). Samea multiplicali ((Lepidoptera). Wild host: Eudocima fullonia (Lepidoptera). 
 Invasive behavior information :the plant competes for water, nutrients and space, resulting in a poor crop production. It can replace native flora and benthic fauna are usually decreased under permanent mats of Salvinia. Infestations provide an ideal environment for reproduction of disease causing organisms. For example, it is an important plant host of Mansonia mosquitoes, which are principal vectors of rural elephantiasis. It also shelters mosquito species that are responsible for the transmission of encephalitis, malaria and dengue fever and it has also been noted to harbour snails that transmit schistomiasis. Thick mats of Salvinia prevent the passage of large motor boats and even a single layer of plants is a major obstacle to canoes. As a result, Salvinia can severely impede transport by water, and commercial and recreation fishing. Large mats block access to dinking water by humans, domestic stock and wildlife, clog irrigation and drainage canals, and sweep fences and other light structures ahead of them during floods. 

Bibliography

 Bibliography :