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Salvinia molesta

(African Payal)

Overview

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Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in Afrikaans:

Watervaring

Common Names in English:

African Payal, African Pyle, Aquarium Water Moss, Aquarium Water-Moss, Aquarium Watermoss, Butterfly Fern, Cats Tongu, Giant Salvinia, Kariba Weed, Kariba-Weed, Koi Kandy, Salvinia, Water Fern, Water Spangles

Common Names in Informal Latinized N:

Salvinia

Description

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Genus Salvinia

Stems with many multicellular hairs . Leaves horizontally spreading . Blades of floating leaves green and pubescent abaxially (on side away from water). Sporocarps borne on chainlike or cymelike organs or submerged leaves; sporangia indehiscent, dispersed as units when sporocarps decay.

Species ca. 10: mostly tropical , North America, Mexico, West Indies, Central America, South America, Eurasia , Africa including Madagascar.

Leaf development in Salvinia is unique. The upper side of the floating leaf, which appears to face the stem axis, is morphologically abaxial (J. G. Croxdale 1978, 1979, 1981).[1]

Physical Description

Habit: Forb/herb

Flowers: Bloom Period: n/a • Flower Color: inconspicuous, none

Size/Age/Growth

Size: under 6" tall.

Habitat

Preventative measures: The optimum strategy is to prevent the introduction of S. molesta into a wetland or other water body . Legislation may restrict the import of the plant into a country but within-country movement is more difficult to achieve and may depend on increased public awareness and education. This may be addressed by targeting organisations that aggravate spread of the weed , especially those which do so for explicit commercial gain (such as the nursery and aquarium trades). Within-country movement may be limited by encouraging people to identify and report new infestations and limit the spread of existing infestations. Restricting access to heavily infested sites is appropriate if the spread of the weed in an area is associated with activities such as boating, fishing or motor vechicles use. Identifying the potential spread of a weed in an area (by analysing climatic data and salvinia temperature tolerance) help prioritise management policies and determine which areas would benefit the most from control measures (Howard and Harley, 1998; Bowcher and Lee , 2003).

Biological: Research into biological control of S. molesta was aggravated by the high expense of manual removal and the negative effects of herbicide use. A two millimeter black subaquatic beetle (Cyrtobagous salvinae) has proven to be the best candidate for biological control of S. molesta, however, if environmental variables limit its effectiveness an integrated management plan (including a number of appropriate control measures) is necessary (Howard and Harley, 1998; Room and Fernando, 1992).

C. salvinae is absolutely host-specific to Salvinia in all documented field cases and laboratory trials. First collected in 1980 by Australian researchers (from the native range of S. molesta in Southern Brazil), the beetle adults and larvae feed on the leaf buds and young terminal leaves of the plant, causing leaf darkening, senescence and abscission. The beetle larvae also tunnel into the rhizome. The efficiency of control depends on at least four variables: (i) the temperature, (ii) the concentration of nitrogen (which stimulates beetle reproduction ), (iii) the density of vegetation growing among the weed (which reduces beetle dispersal ), and (iv ) rainfall (which reduces the nitrogen content of the weed). The size of the infestation is not important because an increase in weed biomass supports exponential growth of the beetle population for a longer period of time, therefore resulting in increased population growth rates . Cool temperatures (such as occur in southern Australia) or, alternatively, high temperatures have been corellated with lower densities of C. salvinae and lower levels of control. Optimum beetle population occurs between 27°C and 31°C; reproduction ceases below 21°C. In contrast S. molesta may continue to grow at temperatures as low as 12°C. An investigation into the climatic variables that affect the establishment of C. salvinae (undertaken at Kakadu National Park in Australia) suggest that decreases in beetle population growth rates may be caused by a late wet season followed by flooding or a poor wet season (either absent or halted). A low weed density also limits the ability of beetles to establish (perhaps the reason why biological control is less effective in cooler regions, which sustain a lower density of weeds) (Room and Fernando, 1992; Room, et al., 1981; Forno, Sands and Sexton, 1983, in Pieterse et al, 2003; Sands, Schotz and Bourne , 1986, Room, 1986, in Dye and Heinz, Biological control of Salvinia species, Bowcher and Lee, 2003; PIER , 2003). Biological control of S. molesta using C. salvinae has been successful in at least 16 countries and is relatively cheap and efficient. In addition to economic efficiency, the use of C. salvinae rather than herbicide to control S. molesta has incalculable environmental benefits (Pieterse et al, 2003; Room and Fernando, 1992; Chikwenhere and Keswani, 1997).

Typically found at an altitude of 0 to 590 meters (0 to 1,936 feet).[2]

Ecology: ReproductionS. molesta produces egg-shaped, slender-tipped sporocarps that develop in elongated chains along the submersed fronds. Sporocarps contain numerous sporangia (which are usually empty or contain only a few deformed spore remnants). Because the plant is pentaploid (contains five sets of chromosomes) it can not produce viable spores (due an unequal division of chromosomes during meiosis). As a consequence S. molesta is sterile and can only reproduce asexually. The plant propagates by vegetative growth and sporadic fragmentation which results in small vegetative propagules that are easily dispersed by water currents (Loyal and Grewal, 1966, in Jacono, 2003).

Biology

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Reproduction

Duration: Depending On The Climate, A Href="/plants/s/sa

Growth

Culture: Space 3-6" apart.

Soil: Minimum pH: 5.6 • Maximum pH: 7.5

Sunlight: Sun Exposure: Full Sun .

Temperature: Cold Hardiness: 8a, 8b, 9a, 9b, 10a, 10b, 11. (map)

Taxonomy

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Notes

Publishing author : D.Mitch. Publication : Brit . Fern Gaz. 10: 251. 1972. 1972

Similar Species

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Members of the genus Salvinia

ZipcodeZoo has pages for 7 species, subspecies, varieties, forms, and cultivars in this genus:

S. auriculata (Eared Watermoss) · S. biloba (Giant Salvinia) · S. cucullata (Asian Watermoss) · S. herzogii (Giant Salvinia) · S. minima (Eared Water-Moss) · S. molesta (African Payal) · S. natans (Floating Watermoss)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 22, 2007:

Identifiers

Footnotes

  1. "Salvinia". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
  2. Mean = 91.220 meters (299.278 feet), Standard Deviation = 111.980 based on 46 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/14/2012