Sparaxis is a genus in the Iridaceae family that is endemic to South Africa and found mostly in the southwestern Cape and the western Karoo.

Sparaxis roxburghii, synonymously known as Synnotia bicolor var. roxburghii or Synnotia roxburghii and commonly known as Collar Satinflower, is a critically endangered and rare South African endemic species found in the Western Cape where it occurs in a few small subpopulations in the Olifants River Valley between Citrusdal and Clanwilliam, growing amongst fynbos in shale-derived, stony clay soils. It has bilaterally symmetrical mauve to lilac flowers with yellow on the two thirds to lower half of the lower tepals. The throat is yellow with dark streaks. The perianth tube is obliquely funnel-shaped, 20-30 mm long. It is distinguished by its long-tubed flowers and the finely fibrous corm tunics that extend upwards in a neck around the leaf bases. Growing from 28 to 45 cm, it flowers late August to mid-September.