The Branching Aristea (Aristea dichotoma) flowers on the Common from December till February, although recent thefts of this tough little bulb have reduced the population to virtually nothing. The flowers only last one day - opening in the morning and fading in the afternoon - the drying petals twisting into a spiral which you can see clearly in the photograph above.
Its leaves are tough, narrow and point upwards to avoid direct sunlight. Although the stems of this aristea are characteristically branching, the specimens on the common don't branch all that much. The flowers are about 15-20 cm high.
Information from Fiona Watson, Cape Bulbs by John Manning and iSpot.