Cyrtanthus is a large genus of the Amaryllidaceae family native to South Africa. Species are found growing in a wide range of habitats including damp bushy stream-edges, as epiphytes on other plants, and in near desert conditions. A good reference is Graham Duncan's The Amaryllidaceae of Southern Africa written in 2016. Cyrtanthus species k-o are found on this wiki page.
Cyrtanthus leucanthus Schltr. grows on sandy and rocky flats in the southwest Cape from Betty's Bay to Potberg, flowering January-March. It has grasslike foliage than appears after flowering, a hollow stem and pale cream scented long tubed flowers. It is another species stimulated to bloom by fires. You can find a short article here. Photos from iNaturalist taken in February and March by carinalochner, Jenny Parsons, and magrietb and shared under a CC BY-NC license.
Cyrtanthus loddigesianus (Herb.) R.A.Dyer (syn. Cyrtanthus speciosus R.A.Dyer) is a summer-growing species from the southern part of the Eastern Cape where it grows in grassy fynbos or in grassland in coastal sands. It flowers late spring to late summer. Leaves die back in late autumn and the plant is dormant in winter. It has 2 to 6 funnel shaped erect cream or white flowers with green, greenish-yellow or pinkish-red median strips along the inner and outer surface. This floriferous species is one of the easiest Cyrtanthus species to grow. The first four photos from iNaturalist taken by Adriaan Grobler and Friends of St Francis Nature Areas and shared under a CC BY-NC license. The last photo by Bill Dijk.
Cyrtanthus mackenii Hook.f. is an Eastern Cape species with evergreen and deciduous forms. The evergreen form grows in stream beds in riverine forest patches near the south east coast of South Africa, always in shade. Often it grows between rocks in the streams beds with the bulbs submerged in water or on the edges of pools. Wild populations usually only flower in July and August (late winter).
The evergreen forms are some of the most easily grown of all Cyrtanthus species. They flower when they feels like in captivity, especially when hybridised with similar species (like Cyrtanthus brachyscyphus). These forms are ideal container subjects, garden plants and cut flowers. Numerous colour forms exist and all are delightfully scented. This species is particular ornamental when different colour forms are grown together in the same container. It likes to remain undisturbed for many years for best results. The first photo below is a photo by Bill Dijk of a white flowered form. Photos 2-4 were taken by Hans Joschko of various colored forms. The last image shows 2-month-old seedlings, photo by Byron Amerson.
Cyrtanthus mackenii var. cooperi (Baker) R.A.Dyer is an inland form that is widespread found growing in full sun in moist grassland. It differs by being deciduous, having shorter more grey leaves, flowering in early spring (from July to September) before the leaves appear, and is a dull pinkish yellow (in contrast to the evergreen form which is clear, bright yellow). Photos by Cameron McMaster of this species in the Eastern Cape near Stutterheim.
Cyrtanthus mackenii ssp. mackenii is an evergreen yellow form that flowers on the edges of pools in sheltered streams near the coast in the Eastern Cape. Photos by Cameron McMaster.
Cyrtanthus macmasteri Snijman was described in 2003. It has large red flared flowers and was named after Cameron McMaster who saw a specimen in 1994 when with his family in the Bolo River Gorge in the Eastern Cape. He did the follow up work to locate where it grew and to obtain specimens so the necessary documentation could be done so it could be verified and named. He has kindly provided an article first published in Veld and Flora, March 2004, about this experience. This species grows in thick grass between rocks on steep slopes, often shaded by shrubs and trees. It blooms in the wild in February and March. Photos by Cameron McMaster of the flowers and the habitat.
Cyrtanthus macowanii Baker is a summer flowering species with red tubular flowers and is widespread in the Eastern Cape. This species is very similar to Cyrtanthus epiphyticus and according to Graham Duncan's The Amaryllidaceae of Southern Africa it differs mainly in its spreading, not recurved tepals. However, the illustrations of the two species in that book do not show this distinction. Plants are summer growing and more or less evergreen. Photos by Cameron McMaster and Mary Sue Ittner taken in habitat in the Eastern Cape.
Cyrtanthus montanus R.A.Dyer grows in rock crevices on upper slopes in the southeastern Cape, flowering January-March. It is one of the most striking species, producing orange umbels in autumn. This plant requires very infrequent watering; there is nothing quite as irretrievable as a bulb of C. montanus once it has started to rot. Usually evergreen, but needs to be almost bone-dry in winter. Photos by Bill Dijk and Cameron McMaster of this species that is very rare in the wild.
Cyrtanthus obliquus (L.f.) Aiton is a widespread species native to the E. Cape from Knysna to the Kei River mouth. The climate is subtropical with rainfall in both summer and winter but more so in summer. The habitat receives 400-500 mm per year. The plants can be seen as clumps, often in rock outcrops among succulent plants. The plant in flower is impressive in every way; its twisted evergreen, glaucous foliage combines magnificently with the sturdy peduncle or stalk of pendulous, yellow, red and green flowers. Adult plants prefer full sun, with at least two-third of the large bulb above ground. It requires much less water in winter, and blooms in spring and summer. At Kirstenbosch BG, the plants do fine even with regular watering during the winter. Seedlings seem to not like full sun and do best in part sun.
The first two photos were taken by Bill Dijk and John Ingram. John wrote: "This is the first bloom for me for this species. I have had the bulbs for almost 3 years now and they were either 3 or 5 years old when I got them. I am amazed at the thick solid texture of the flowers. There is some snail damage on flowers on the backside and trails are evident in the photo but I think once the flowers get past a certain age, they are too hard for the snails to consume." The last two photos were taken by Roy Herold at the Karoo Desert NBG in Worcester, October 2002.
This species is native to the southeastern Cape where it is found on exposed rocky outcrops where its bulbs are crowded between rocks or cling to steep cliffs. Photos of a plant in habitat taken by Cameron McMaster, a close-up, and a picture of the plants with seed capsules.
Cyrtanthus obrienii Baker is native to the eastern summer rainfall zone of South Africa. It is a grassland species found on stony hillsides, growing in thick clumps in rock crevices in full sun. The leaves appear before the flowers in late winter and spring, dying back in autumn. It flowers July to October. In cultivation it is an evergreen spring species with red pendulous flowers. It is fairly attractive and quite a tough plant, preferring to stay in the same position for many years. Photos by Cameron McMaster and Alessandro Marinello.
Cyrtanthus odorus Ker Gawl. is found on the lower to middle slopes in the Langeberg Mountains near Swellendam where it grows on stony sandstone soils in fynbos vegetation. It usually only flowers in late summer and autumn after a summer bush fire. The flowers emerge from dry soil, followed by the leaves. On iNaturalist, plants were seen flowering November-January. Growing to 30 cm high, it has one to five narcissus scented dark red flowers. It is considered endangered because of loss of habitat. Photos from iNaturalist taken by Nick Helme in November near Swellendam and shared under a CC BY-NC license.