Croton insularis (EUPHORBIACEAE) Silver Croton

Plants to Plant

Small tree up to 15 m in dry rainforest and its margins, Blue Mountains, NSW to Cape York, Queensland. Fruit is a greyish, globular capsule about 6 mm in diameter and is ripe November to January. Hardy plant which is a suitable size for a small garden. The silvery undersides of the leaf contrast well with the green foliage and old leaves turn scarlet before falling. Propagate from fresh seed and cuttings. The bark of this plant was used as a reddish brown dye for cotton and woollen garments.

Photo: Sheldon Navie

Flowers

Flowers are cream to silvery brown in racemes from the leaf axils from June to October. The genus name croton is derived from the Greek word kroton meaning tick, which refers to the resemblance of the seeds of this genus to ticks. There are approximately 750 Croton species worldwide with approximately 23 occurring in Australia (mostly all endemic). The local Crotons range in size from shrubs up to small trees. They have alternate leaves and bear unisexual flowers in racemes (an inflorescence of stalked flowers arranged along a single main axis). Fruit is a two to three-celled capsule which splits open when ripe.

Photo: Robert Whyte

Foliage Undersides

The rainforest communities in the Brisbane region contain five described Croton species:

  • Thick-leaved Croton Croton acronychioides
  • Silver Croton Croton insularis
  • Narrow-leaved Croton Croton phebalioides
  • White Croton Croton stigmatosus
  • Native Cascarilla Croton verreauxii
Photo: Sheldon Navie

Foliage with Older Leaves Close-up

The injured bark of this plant produces a pleasant aromatic smell which resembles the odour of the West Indian Cascarilla Tonic which is a cure-all medicineextracted from a Caribbean plant closely related to Croton insularis. Another of the common names of Croton insularis is Queensland Cascarilla Bark. Silver Croton can usually be found growing on the edge of rainforest and is a common small tree in dry rainforest regrowth. In full sun it has a tight, rounded crown with the silvery underleaf contrasting with the odd sprinkling of red-orange old and dying leaves.

Photo: Robert Whyte