Many species of the genus Streptocarpus are inhabitants of afromontane forest biotopes. These are forested areas with high humidity and relatively cool temperatures. Some species occur in very moist areas surrounding waterfalls but many have also adapted to drier climates and occur in more exposed positions. Many survive in cracks between rocks in true microclimates which provide enough moisture and shade [link to S. pusillus in crack, already on website].
In general, it can be said that Streptocarpus prefer broken terrain such as steep mountain slopes and river gorges. They also often grow on steep earthen banks [*, link to pic of S primulifolius on earth bank] or on rocks [*, link to S formosus in nature on rocks] and in certain instances will even grow epiphytically [*, link to pic of S primulifolius on log in Port St Johns, and S haygarthii on Ngeli Mountain]. Companion species often include balsams or Impatiens species [*, will supply pic], Plectranthus species [*, will supply pic] and Begonia sutherlandii [*, will supply pic], as well as mosses and ferns.
The main concentration of species in subgenus Streptocarpus is in South Africa and in subgenus Streptocarpella in Tanzania, whilst in Madagascar quite a number of species of both subgenera occur. In South Africa, at the most southern end of the distribution of subgenus Streptocarpus, which starts in the southern Cape near the town of George (east of Mossel Bay on the map), they occur at sea level in cool coastal afromontane forests. Further north, they also occur at higher altitude in large areas of Kwazulu-Natal Province, where the many remnant patches of forest provide an important habitat for them. Many other species have developed in the cooler higher lying areas of the Natal Drakensberg mountain range on the border between Lesotho and Kwazulu Natal, Free State Province, Lesotho and Swaziland.
The distribution of the genus continues further north into the Mpumalanga Province of South Africa which has a low-lying area (the Kruger National Park occurs here) (link to S. fasciatus) and a very much higher lying area developing at an abrupt escarpment where the Natal Drakensberg extends further north. Here Streptocarpus occur on the escarpment and higher lying areas (link to S cyaneus). The Transvaal Drakensberg as it is called, then leads further north to the Wolkberg and Magoebaskloof area in central Limpopo where Streptocarpus are also found. A few species occur on isolated mountain peaks in the northern provinces (link to S rimicola, I must send you the latest pic). Finally, in the Limpopo Province of South Africa, the Soutpansberg mountain range (link to S. caeruleus) and the Blouberg, with higher cooler elevations presents the most northerly extent of their range in South Africa. this para needs to be edited — Wolkberg and Magoebaskloof are in Limpopo, but it doesn’t read like this — text has been adjusted to reflect, but needs further work.
Fewer species of subgenus Streptocarpus also occur further north, but most definitely not on the hot low-lying plains but only on the higher lying areas of Zimbabwe in the Chimanimani Mountains and Inyanga, and in Malawi on the Nyika, the Vipya, Dedza and Zomba Plateaus as well as the mighty Mount Milanje and the Shire Highlands. In Mozambique they are found in the higher lying areas at Ribaue, Gurue, Murrumbala and Gorongoza. In the Congo, they only occur on high lying areas at Lakufu and Marungu, in Zambia in the north-east and in Angola at Lubango (formerly Sa da Bandeira).
An abundance of species is again found in Tanzania. They occur in the southern highlands and then along the higher peaks of Mt. Image to the Uluguru and Nguru Mountains. In northern Tanzania, they are found on the higher peaks in a line from the coastal port of Tanga to the inland town of Arusha i.e. the East and West Usumabara Mountains, South and North Pare Mountains and then on Mount Kilimanjaro, Mount Meru and Mount Longido. Further north in Kenya they are found in the Teita Hills and Thika as well as the Aberdare Mountains and Mount Kenya. Finally, in Uganda in the Ruwenzori Mountains and in the Ethiopian highlands, a few species are to be found. Species of subgenus Streptocarpus occur throughout this range, while the true tropical areas in Tanzania and Kenya are the home of subgenus Streptocarpella. In Tanzania their habitat is often shared with the Saintpaulias.
The occurrence of Streptocarpus in the Congo is very poorly documented, and many undescribed species may still occur there. Further west to countries such as Cameroon and Nigeria, a limited number of Streptocarpus species of the subgenus Streptocarpella occur, such as Streptocarpus nobilis.
My knowledge about the Streptocarpus habitats in Madagascar is very limited but once again they seem to grow in similar habitats. Finally a few species occur on islands in the north-western Indian Ocean such as the Comoro Islands and a few others are found in Asia. It has however now been shown conclusively using molecular systematics, that the Asian species are not true Streptocarpus and should be excluded from the genus.