"isopogon trilobus" grows as a shrub anywhere from in height. the new stems are pale to reddish brown, and initially covered with small fine hairs before becoming smooth. its leaves are highly variable and have anywhere from three to nine small to deep lobes. the barrel-shaped yellow inflorescences appear from september to january and are terminal (occurring on the ends of stems). measuring across, they contain many yellow or cream individual flowers. flowering is followed by the development of relatively large hairy grey fruit.