Illyarrie is a small tree usually with an open crown, growing 6-8m high. Of all the eucalypts, illyarrie has one of the largest and certainly the most striking and unusual budcaps. When this unique operculum is shed, mainly form March to May bright yellow anthers, set as a cross, form the flowers. This colourful combination of features identifies the species beyond all doubt. Erythrocorys means Red Helmet referred to by the budcap. It favours sandy, or calcareous soils, and in nature forms a small tree, sometimes rather straggly, with a white, smooth bark. Adaptable to most soil types, where the rainfall is at least 450mm annually.