Conium maculatum

Hemlock

Also known as:

Poison hemlock

Family: Apiaceae

Origin: Eurasia and North Africa

Hemlock mature plant.
A perennial shrub poisonous to humans and livestock. Vigorous growth that can grow in degraded soils and roadsides.
Photo credit: Jonathan Boow

Regional Pest Management Plan (RPMP) status

  • Hauraki Gulf Controlled Area Notice pest
  • Whole region — Sustained control

View more about the RPMP statuses

General description

Foul-smelling, perennial, annual or biennial herb < 2.5 m tall. Taproot is thick. Stems are smooth, hollow, branching and spotted or streaked, with a red/purple lower half. Leaves are < 50 x 40 cm, pinnate, fern-like, lacy and triangular. Flowers are small, white and borne in umbels.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell hemlock within the Auckland region.
  • You must not plant hemlock within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • You must destroy any hemlock on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Habitats

Damp areas, swamps, roadsides, riparian areas, forest margins, pasture, ditches, wasteland.

Dispersal

Seeds dispersed by wind, water and attachment to animal pelts. Human-mediated dispersal through contamination of clothing, machinery, gravel and soil.

Impact on environment

Acutely poisonous and poses severe health risks to humans, livestock and native fauna. Can cause fatality.

Control

Site management

Will quickly become succeeded by taller native species so only control in open or sensitive areas. If spraying remove all stock from the area as the plant material will become palatable after spraying. Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig out.

Plant parts requiring disposal: Seeds.

Disposal options: Remove to greenwaste or landfill if practical to prevent stock from eating it.

Biocontrol

Check for presence of agents: Hemlock moth (Agonopterix alstromeriana).

For more information about how biocontrol works, see What is biocontrol?

Community agrichemical control recommendations

No qualifications: Foliar spray with 100ml glyphosate green per 10L of water.

Safety notes

Acutely poisonous.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.