Eucalyptus erythrocorys

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Scientific classification e
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Myrtales
Family: Myrtaceae
Genus: Eucalyptus
Species: E. erythrocorys
Binomial name
Eucalyptus erythrocorys
E. erythrocorys.JPG
E. erythrocorys, field distribution
Flowers and leaves of an Illyarrie (Eucalyptus erythrocorys), Margaret River, Western Australia
Flower buds and opercula
Eucalyptus erythrocorys habit

Eucalyptus erythrocorys, commonly known as Illyarrie, Red-capped gum or Helmet nut gum,[1] is a mallee from Western Australia. The common name Illyarrie is the Noongar peoples name for the plant.[2]


It is a small tree with an open spreading habit[3] typically growing to a height of 3 to 10 metres (10 to 33 ft) and a width of 3 to 6 metres (10 to 20 ft).[4] The bark is smooth[5] with a creamy colour but can have a few rough brown coloured patches where it persists on the trunk instead of being shed. It sheds in short ribbons or small polygonal flakes.[6] The adult leaves are dark green sickle-shaped.[1] The dull, green, thick, concolorous adult leaves have an opposite arrangement. The blade has a narrow lanceolate shape, falcate, acuminate and are basally tapered. Leaves are supported by narrowly flattened or channelled petioles.[6]

Prior to flowering it forms large rectangular scarlet[1] pyriform or clavate buds.[6]

It blooms between February and April and produces inflorescences with yellow flowers.[5] Illyarrie is notable for its big flowers which can be up to 7 centimetres (3 in) in diameter and occur in groups of three.[1] They are bright yellow, being covered by a bright-red cap (operculum) in bud - giving the epithet erythrocorys (red-helmet). The stamens are arranged in 4 bundles and the fruits are ribbed with a red top.

Following flowering fruits form that are campanulate and pedicellate with a raised disc and exserted valves.[6] Sometimes the fruit are so numerous that they weight the tree down[1] so that it has a weeping habit.[7]


The species was first formally described by the botanist Ferdinand von Mueller in 1860 as part of the work Fragmenta Phytographiae Australiae.[8] The type specimen was collected by Augustus Frederick Oldfield in 1858 from along the Murchison River and is cited as Ad flumen Murchison et sinum squalorum versus in planitibus petraeis.[6]

The species is a member of the sub-genus Eudesmia, this group has stamens that are in four bundles each at the corner of the squareish flower. It is in a sub-group that includes Eucalyptus pleurocarpa.[1]

The species name erythrocorys is taken from the Greek words erythro meaning red and korys meaning helmet in reference to the bright red operculum.[1]


The species has a limited distribution north of Perth where it is found on undulating limestone ridges and outcrops growing in sandy alkaline soils near Dongara as well as north of Kalbarri National Park.[1] It is also found on sandy plains, particularly the Geraldton Sandplains between Shark Bay and Jurien.[9]


The plant is sold commercially in seed form[10] or as tube stock[3] and is a popular species throughout Australia. The seeds germinate readily.[7] It can become untidy but is easily kept in shape with a light pruning. The colourful flowers make it appealing to nectar loving birds.[9] The trees are known to shed limbs as a result of the weight of the fruit they carry.[4] It is reasonably fast growing and both drought and smog resistant[11] but can be frost tender.[7] It prefers a position in full sun, in well drained soils and can be grown in containers and in coastal locations. The flowers are used in wreaths.[11]

See also[edit]


  1. ^ a b c d e f g h "Eucalyptus erythrocorys". Australian Native Plants Society. 2016. Retrieved 30 November 2016. 
  2. ^ "Noongar names for plants". Retrieved 30 November 2016. 
  3. ^ a b "Eucalyptus erythrocorys 'Red Cap Gum'". Ellenby Tree Farm. Retrieved 4 December 2017. 
  4. ^ a b "Illyarrie Eucalyptus erythrocorys" (PDF). Native Plant Notes. Kings Park and Botanic Garden. Retrieved 3 December 2017. 
  5. ^ a b "Eucalyptus erythrocorys". FloraBase. Western Australian Government Department of Parks and Wildlife. 
  6. ^ a b c d e "Eucalyptus erythrocorys". Eucalink. Royal Botanic Garden, Sydney. Retrieved 3 December 2017. 
  7. ^ a b c "Eucalyptus erythrocorys". Australian Seed. Retrieved 4 December 2017. 
  8. ^ "Eucalyptus erythrocorys F.Muell". Atlas of Living Australia. Global Biodiversity Information Facility. Retrieved 3 December 2017. 
  9. ^ a b "Plant of the Month — March 2004 Eucalyptus erythrocorys F.Muell. — Illyarrie". Florabase. Western Australian Herbarium. Retrieved 4 December 2017. 
  10. ^ "Eucalyptus erythrocorys Illyarrie". Nindethana Australian Seeds. Retrieved 4 December 2017. 
  11. ^ a b "Eucalyptus erythrocorys". Australian Native Plants. Retrieved 4 December 2017. 

Further reading[edit]

  • Holliday, I. A field guide to Australian trees (3rd edition), Reed New Holland, 2002