Salvinia minima
| Salvinia minima | |
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| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pteridophyta |
| Class: | Polypodiopsida/Pteridopsida (disputed) |
| Order: | Salviniales |
| Family: | Salviniaceae |
| Genus: | Salvinia |
| Species: | S. minima |
| Binomial name | |
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Salvinia minima Baker, 1886 |
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Salvinia minima is a species of aquatic, floating fern that grows on the surface of still waterways. It is usually referred to as common salvinia or water spangles. Salvinia minima is native to South America, Mesoamerica, and the West Indies and was introduced to the United States in the 1920s-1930s. It is classified as an invasive species internationally and can be detrimental to native habitats. This species is similar to but should not be confused with giant salvinia, Salvinia molesta.
The leaves of Salvinia minima are small and oval, ranging from 0.4 to 2 centimeters in length. Each rhizome of the fern floats close to the surface and has a joined set of leaves that branch off horizontally. The leaves grow in joined sets of three, with two leaves floating on the surface and one leaf dissected, hanging underneath. This species is rootless but the dissected leaves that hang down act as root-like structures and are longer than the floating leaves. Fine white hairs grow uniformly on the leaf surface and serve to repel water. The hairs grow close together in groups of four, bending out and touching together at their top ends to form a whisk or eggbeater-like shape. There are longer brown hairs present on the underside of leaves as well. Leaves range from bright green to brown in color, often browning with age and in sunlight.
Salvinia minima undergoes three unique stages of growth. In the primary (initial) stage, a single bud or a small number of buds of the fern are introduced to an environment. In this stage, the leaves will lie flat on the surface of the water. In the secondary stage, the ferns have been growing and multiplying and the leaves will begin to curl upward. In the tertiary (final) stage, the individual ferns will become much more dense and appear as mats on top of the water. The leaves may be almost vertical in this stage because of crowding.
Reproduction in Salvinia minima occurs asexually through fragmentation. Though sporocarps, spore-producing sacs, may be present on the leaves of this species, Salvinia minima is thought to be sterile and can only reproduce asexually. Any part of a rhizome that buds or breaks off can form another daughter plant. Since fragmentation can occur continuously, Salvinia minima often shows exponential growth. Buds and rhizome fragments can also remain dormant for periods of time when growth is less favorable.
Salvinia minima commonly grows on the surface of still or slow-moving freshwater areas, such as lakes, ponds, and canals. It can tolerate water salinity of up to 4 to 7 parts per thousand (ppt) (or 1.003-1.005 SG) and also inhabits brackish water, including swamps, marshes, and wetlands. This species can also be found in backyard ponds and private lakes and can be purchased in states where it is not prohibited as a noxious plant.
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Wikipedia