This plant is a woody shrub growing up to about 1 m high. It is moderately well-branched so it is often as broad as it is high. In flower, the shrubs are covered with lemon-yellow flower heads, borne singly at the ends of the branches. The leaves are small, narrow and rounded, and are crowded into tufts arranged opposite each other on the stems. The branching pattern of the twigs is also opposite. A dense covering of white hairs on the upper leaf surface and on the young stems is responsible for the silvery-green appearance of the plant. The involucre (the lower part of the flower head that protects the seeds) is narrow, and consists of dry bracts (leaf-like structures which have taken on a different function from photosynthesis) which overlap each other like inverted roof-tiles. The base of each bract is greenish and tightly pressed against the flower head, while the tip is pale brown and curls away from the flower head. The flowers themselves are pale yellow, and the reproductive parts (style, stigma and anthers) protrude above the flower head.

Note: in the daisy family or Asteraceae, what looks like a flower is actually an aggregation of very small flowers into a flowerhead. This flowerhead is similar to that found in the proteas, but in the daisies usually contains two kinds of flowers:

small, tube-shaped disc flowers in the centre

and long strap-shaped ray flowers around the margin.

Both of these kinds of flowers are present in Antithrixia flavicoma.

Antithrixia flowers in late spring (October to November). The seeds are dispersed by wind, and to enhance wind dispersal the seeds are equipped with a pappus of hair-like bristles.

Antithrixia could be confused with members of the genus Pteronia, which also have leaves arranged opposite each other on the stems, and occur in similar habitats. However, Pteronia flower heads never have ray flowers.