Cyrtanthus is a genus of bulbs in the family Amaryllidaceae, most of which originate from South Africa. This particular species, C. spiralis, bears leaves which as its name suggests are spiral or perhaps, more strictly, helical. The leaves grow to around 15cm, and in my greenhouse (kept above freezing) are borne for most of the year. The plant is fairly slow growing - the specimen pictured took several years to grow to flowering size from a small offset bulb. It appears to come easily from the large round flat black seeds. I have a pot full of seedlings grown this year from seeds obtained from Silverhill Seeds in South Africa.
I also grew seedlings of Cyrtanthus helictus, which have developed the same
spiral/helical leaves, but these have distinguished themselves by losing all their
leaves and going dormant for Winter.