The word vlei is used predominantly in South Africa. In most instances a vlei is a shallow minor lake of a seasonal or intermittent nature. It even might refer to seasonal ponds or marshy patches where frogs and similar marsh dwellers breed, but too minor to be granted recognition in the form of a name. However, some major vleis are accorded names, for example Rondevlei and Zeekoevlei

Zeekoevlei

Zeekoevlei is a major freshwater lake on the Cape Flats near Cape Town, Western Cape Province, South Africa. The name means "hippopotamus vlei," with "vlei" being afrikaans for "lake", and "zeekoe" being an archaic spelling of the afrikaans for hippopotamus.Zeekoevlei Nature Reserve is based on...

 in the Cape Peninsula

Cape Peninsula

The Cape Peninsula is a generally rocky peninsula that juts out for 75 km into the Atlantic Ocean at the south-western extremity of the African continent. At the southern end of the peninsula are Cape Point and the Cape of Good Hope...

, which are permanent bodies of water. Indeed, Rondevlei is home to hippopotamus.

The word vlei is of Dutch

Dutch language

Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...

/Afrikaans origin, meaning 'pond' or 'marsh' and is pronounced "flay". Commonly, vleis vary in their extent, or even in the presence or absence of water, according to the fall of rain or dryness of the season. Vleis of various types can be of considerable local ecological importance, harboring many endemic and migratory

Animal migration

Animal migration is the relatively long-distance movement of individuals, usually on a seasonal basis. It is a ubiquitous phenomenon, found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The trigger for the migration may be local...

 species.

In terms of water salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

, vleis may be freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

, saltwater

Seawater

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

, or brackish.

Over time a vlei may degrade into a salt pan

Dry lake

Dry lakes are ephemeral lakebeds, or a remnant of an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Dry lakes are also referred to as alkali flats, sabkhas, playas or mud flats...

 or clay pan

Dry lake

Dry lakes are ephemeral lakebeds, or a remnant of an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Dry lakes are also referred to as alkali flats, sabkhas, playas or mud flats...

, such as Dead Vlei

Dead Vlei

Deadvlei is a white clay pan located near the more famous salt pan of Sossusvlei, inside the Namib-Naukluft Park in Namibia. Also written DeadVlei or Dead Vlei, its name means "dead marsh"...

.

The term is the basis of various biological common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

s such as "vlei rat

Vlei Rat

The Southern African Vlei Rat is a species of rodent in the Otomys genus of the family Muridae.It is found in Lesotho, Mozambique, South Africa, Swaziland, and Zimbabwe....

" for rodents in the genus Otomys, "vleiroos

Orothamnus

Orothamnus or 'Marsh Rose' is a monotypic fynbos genus in the family Proteaceae occurring in the Kogelberg and Kleinrivier Mountains of Hottentots-Holland in the Western Cape Province of South Africa...

" (literally "marsh rose"), vleikuiken

Flufftail

The flufftails are a genus, Sarothrura, of small birds in the rail family. The genus is restricted to seven species distributed across sub-Saharan Africa, and two species found in Madagascar. The group's common name is derived from the short tail which has degraded fluffy feathers...

" (literally "vlei chick") and vlei frog.