|E. macrocarpa, field distribution|
It is sprawling in habit and grows to between 0.8 and 5 metres in height. The silver-grey leaves are ovate-elliptic, sessile and are up to 12 cm long and 8 cm wide. The red, pink or cream flowers are up to 100 mm in diameter and occur in early spring to summer and from late autumn to early winter. They are followed by large bowl-shaped "gumnuts" which give rise to the Greek-derived specific name macrocarpa – "makros" (large) and "karpos" (fruit). They are covered in a whitish bloom.
The flowers form a striking display, contrasting with the white powdery appearance of the leaves and branches, and, as William Jackson Hooker says, "[t]he colour of the flowers is due to the stamens alone; for petals (as in the genus) there are none, and the calyx falls off like the lid of a box." He notes that it is common in the region of Drummond's collection, and that a name for the species was Morral. The first description of the species was by Hooker in Icones Plantarum, using a dried specimen in James Drummond's collection from the Guangan.
There are three subspecies as follows :
- Eucalyptus macrocarpa subsp. elachantha Brooker & Hopper
- Eucalyptus macrocarpa subsp. elachyphylla Brooker & Hopper
- Eucalyptus macrocarpa subsp. macrocarpa
- "Eucalyptus macrocarpa". FloraBase. Department of Environment and Conservation, Government of Western Australia.
- "Eucalyptus macrocarpa Hook.". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- Association of Societies for Growing Australian Plants (ASGAP): Eucalyptus macrocarpa
- Euclid: Eucalyptus macocarpa subsp. elachantha