Hemlock (Conium maculatum)

Photo: (c) Stefan.lefnaer CC BY-SA 4.0 license

Family: Apiaceae

Growth Habit: An erect plant which can reach a height of 2.75 m, but normally averages 1-1.5 m. Hemlock has hollow, pale green stems with red or purplish patches on the lower stem. The plant also has large, pale green leaves, similar to carrot leaves, but  can be distinguished by its unpleasant smell, the smooth texture, light green color and the presence of blotches on the stems.

Type of Plant: Hemlock can be an annual or biennial.

(c) Sylvain Piry CC BY-SA 2.0 FR license

Flowers: Broad flower heads are produced in summer, which comprise hundreds of tiny white flowers, loosely clustered and each flower has five petals.

Fruit/Seed: Thousands of tiny seeds are produced in autumn.

Dispersal: Reproduces by seed, and from fragments of the root system if disturbed, such as by earthmoving equipment. The  main method of dispersal is in water, or by being carried on animals and vehicles.

Distribution: Hemlock can be usually found on disturbed ground or in damp areas. It is also common on roadsides.

Status: Secondary in Tasmania.

Weed Impact:

  • All parts of the plant are poisonous to both humans and livestock. This is due to the presence of 5 alkaloids, coniceine and coniine being the most active.
  • The plant is toxic either green or dried in hay.
  • Rarely causes significant economic losses to crops.

For further information contact the Department of Primary Industry, Parks, Water and Environment, Tasmania.

Control Methods:

  • Grubbing (all year). Isolated plants may be manually removed with a fork or similar tool. Wear gloves as this plant has poisonous properties.
  • Herbicide (spring, summer). Herbicides registered in Tasmania include 2,4-D, triclopyr, MCPA + glyphosate. BE WARNED: As herbicide treated plants are attractive to stock, they must be kept away till plant completely disintegrates.

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