Flowering from November on The Mounts is Iris foetidissima also known as “Stinking Iris” or “Roast Beef Plant” after its rather unpleasant fragrance when cut or bruised.

It is a clump-forming evergreen herb to 100 cm, with tough rhizomes immediately below the soil surface.

The flowers are 5–7 cm in diameter and are dull purplish-grey tinged with yellow. More common in Australia is the yellow flowered variant that is often naturalised.  You will find both varieties flowering in Mt Wilson currently. 

At maturity each seed capsule splits into three, each with two rows of round orange seeds of 5 mm diameter, these can persist for several months.

Despite the Royal Horticultural Society giving Iris foetidissima their prestigious Award of Garden Merit. The plant is clearly becoming a problem in Mt Wilson, most notably in and around Church Lane.  Each plant grows rapidly and seeds readily and is dispersed by birds. Mature stands will easily smother a garden bed and become extremely difficult to remove.


There are three options to manage this plant:

  1. If you wish to retain any plants, systematically remove any seed capsules before the seeds emerge.
  2. To remove the plants, the most effective way is to mattock out the rhizomes (juvenile plants can usually be removed by hand.
  3. Iris foetidissima will respond to Glyphosate (RoundupTM) but the leaves will need to be soaked and secondary spraying may be required.