Phymaspermum acerosum flowerheads of the geelblombos

The flowerheads of Phymaspermum acerosum grow in large, dense, flat-topped to shallowly domed inflorescences at stem-tips. The narrowly cylindrical flowerheads bear less than ten disc florets each and no ray florets. They become about 5 mm long and 2 mm to 3 mm wide.

Flowering may happen throughout the year, but mostly from late summer to early winter (Pooley, 1998; Onderstall, 1984; iNaturalist).