Myrtle-leaf Milkwort (Polygala myrtifolia)

Photo: (c) Kousvet GNU License

Family: Polygalaceae

Growth Habit: Leaves are dense, oval, growing very close to stems, 1.5 – 4 cm long. Stems are purplish with short hairs when young. Smooth and woody when older.

Type of Plant: Erect shrub, 1.5-4 m high.

Photo: (c) Diego Delso CC International

Flowers: Clusters of pinkish-purple pea-like flowers, grouped at ends of branchlets  almost all the year round. 

Fruit/Seed: Fruit is a flat, almost circular capsule to 1 cm wide, containing 2 seeds about 0.4 cm long.  Produces an abundance of seed all year round. 

DispersalGrows readily from seed, dispersed by wind, water, birds, ants,  seed contaminated soil and dumped garden refuse.

Distribution: Likes sandy soil. Widespread coastal areas and roadsides. Also in riparian vegetation and dry forests.

Status: Undeclared in Tasmania, but can be a serious environmental weed, especially along the coast.

Weed Impacts:

  • Serious environmental weed that forms dense thickets in coastal areas, including dune systems, coastal bluffs and heath but also inland grassy woodlands.
  • Dominates shrub canopy, displacing native vegetation and causing habitat loss.
  • Increased fire risk due to high flammability and increased fuel load of dense thickets. Germination stimulated by fire.
  • Produces prolific quantities of seed that can remain viable in the soil for many (3-10) years.

Control Methods:

  • Do not plant Polygala, replace any you have in your gardens.
  • Best from June to October before flowering and seed set.
  • Hand pull small plants, cut and swab larger plants.
  • Herbicide spray the prolific germination of seedlings after
    removal of larger shrubs (best in Autumn).
  • Follow-up required for many years.

N.B. Always check the herbicide label before use.