12- 74.2
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Dyckia cangaphila P.J.Braun, Esteves & Scharf |
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Distribution: Brasilia, Goias
Habitat: on the top of table mountains, in gravel deposits or between reddish rocks of sandstone, sun-exposed or in semi-shadow, ca 680 m. Elev.
Etymology: The term ”pedra canga" is derived from the Indian (Tupi) language, ”Tapanhoa canga" means something like ”head of a negro". Pedra canga occurs predominantly in central and western Brazil. Geologically seen, it is a substrate which has its origin in subsurface deposits and crusts of iron oxides. After long periods of erosion, these crusts were exposed to the surface. They may occur as compact crusts or as gravel deposits after relocation processes. In the absence of suitable rock deposits nearby, quite often large areas of pedra canga were removed and used for road construction. As the material is soft and not very resistant, fresh supply is regularly required. Many of the large occurrences have already completely vanished, which also means the total loss of the mostly endemic flora. In former times, pedra canga was also used for house building. Roquette-Pinto (1954), e.g., gives a report of Sao Luiz (today the city of Caceres in Mato Grosso) with a ”ruin of a church with big, chocolate-brown ashlars revealing the presence of pedra canga" (free translation). Still today, churches completely built of pedra canga can be visited, e.g., near Bela Vista in Mato Grosso do Sul. Unfortunately, quarrying pedra canga in most cases causes the loss of Discocactus, Dyckia and Bromelia habitats.
