Tzaneen is Limpopo's paradise and it has been nicknamed 'Land of Silver Mist' because of the frequent mist that occur on the mountains above it. It is located in lush, tropical surroundings and is home to Limpopo's highest mountain, the Iron Crown Mountain, lying more than 2200 m above sea level. The Iron Crown mountain, also known by its Afrikaans name Wolkberg, supports Limpopo's biodiversity and is home to South Africa's second largest indigenous forest after Tsitsikamma forest in the southern Cape. Weather can change very fast from clear skies to being misty, with the highest reaches enveloped in clouds. Hence the name of the range, meaning Cloud Mountain in Afrikaans. The Wolkberg is rugged, with rocky shoulders and deep humid gorges. There are rare plant and animal species in these areas. Species such as the Wolkberg Zulu (Alaena margaritacea), the Wolkberg widow (Dingana clara) and the Wolkberg sandman (Spialia secessus), have been named after these mountains. The Wolkberg area is one of only two areas in the world where the critically endangered butterfly, Lepidochrysops lotana, are found. The Iron Crown Mountain is a protected area in terms of South African law. The Groot Letaba River, Middle Letaba River and Klein Letaba River all rise up in these mountains.