Californian Stinkweed (Navarretia squarrosa)

Family: Polemoniaceae

Growth Habit: An erect plant up to 60 cm tall. Usually one stem, the short lateral branches more or less well developed, usually densely covered with glandular hairs and a strong unpleasant odour (thus its other name of Skunkweed). Leaves connect directly to the stem ovate to oblong-lanceolate, 15-35 mm long and 10-25 mm wide, pinnately lobe, narrow, rigid with each lobe ending in a spine.

Type of Plant: Erect annual smelly herb

Photo: (c) Eric in SF CC BY-SA 3.0 license cropped

Flowers: Pale lilac to blue flowers in dense terminal heads, 2–3 cm in diameter. Petals are broadly funnel-shaped, 9-12 mm long. The heads are surrounded by rigid, spiny leafy bracts.  Flowers in summer.

Fruits/Seeds: Capsule ovoid, 3-4 mm long, with numerous seeds.

Dispersal: Disperses via seed.

Distribution: Found throughout Tasmania, starting to increase in numbers. It can be found at elevations of less than 800 metres on open, wet, gravely flats and slopes.

Status: Undeclared in Tasmania, but is an environmental weed.

Weed Impacts:

  • Should be controlled as an emergent weed. Highly invasive and has the potential to become an issue in agricultural and native areas.

Control Methods:

  • Effective hygiene measures to prevent new incursions. Washdown machinery and equipment and ensure soil and feed entering or exerting properties is clean of seed.
  • Hand pulling is possible if you have gloves due to the spines.
  • Spot spraying with herbicide.

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