Eucalyptus macrocarpa

Location & distribution maps

Plant  information

Overview:

• Eucalyptus macrocarpa, commonly known as mottlecah, is a species of mallee that is endemic to the south-west of Western Australia

• It has smooth bark, usually sessile, heart-shaped adult leaves arranged in opposite pairs, large red flowers and broad conical fruit

Common name:         Mottlecah

• Noongar peoples know the tree as mottlecar

Conservation status: Rare (subspecies elachantha)

• Subspecies macrocarpa is classified as "not threatened"

• Subspecies elachantha is classified as "Priority Four" by the Government of Western Australia Department of Parks and Wildlife, meaning that is rare or near threatened

Etymology:   

• The name Eucalyptus is derived from the Ancient Greek words eu meaning 'good'and kalypto meaning '(I) cover, conceal, hide', referring to the operculum covering the flower buds 

• The specific epithet is derived from the ancient Greek words makros (μακρός) meaning "long" and karpos (καρπός) meaning "fruit"

Flowers:                  

• The flower buds are glaucous and are arranged singly in leaf axils on a peduncle 1–7 mm long and a pedicel up to 5 mm long

• Mature buds are oval, 40–55 mm long and 25–30 mm wide with a beaked operculum

• Flowering occurs from August to January or April or June and the flowers are red, or rarely, creamy white

Fruit:                         

• The fruit is a sessile, woody, broadly conical capsule 12–20 mm long and 33–45 mm wide with the valves protruding above the rim of the fruit

Leaves:         

• Its crown is composed of juvenile leaves that are sessile

• These are arranged in opposite pairs, heart-shaped with the bases wrapped around the stem

• They are glaucous, 55–85 mm long and 35–50 mm wide

Stem & branches: 

• It has smooth, shiny, brownish over salmon-pink bark

Roots:         

Habit:        

• A mallee that typically grows to a height of 0.5–8 m, has a sprawling or spreading habit, and forms a lignotuber

Habitat:   

• In sand and undulating heath 

Distribution:                  

• Between Eneabba, Cataby and Kulin. Subspecies elachantha has a more restricted distribution south-east of Geraldton

Additional notes:     

• Taxonomy and naming

  • Eucalyptus macrocarpa was first formally described in 1842 by William Jackson Hooker from a specimen collected by James Drummond from the "guangan"

  • The description was published in Hooker's book, Icones Plantarum

  • In Curtis's Botanical Magazine, Hooker noted "[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 also noted that "the bright red flowers nestled among the leaves, for a very striking object", and that indigenous people called it "morral"

  • In 1993, Ian Brooker and Stephen Hopper described two subspecies and the names have been accepted by the Australian Plant Census:

    • Eucalyptus macrocarpa subsp. elachantha Brooker & Hopper  has smaller leaves, buds and fruit than subspecies macrocarpa

    • Eucalyptus macrocarpa Hook. subsp. macrocarpa; the name elachantha is derived from the ancient Greek words elachys meaning "small" and anthos meaning "flower"

• Use in horticulture

  • Eucalyptus macrocarpa is easily grown from seed, but requires good drainage and a dry, frost-free climate. It was raised from seed in 1842 at Kew Gardens and flowered in 1847

Sources of information:

• https://en.wikipedia.org/wiki/Eucalyptus_macrocarpa (July 2024)