Hyptis

Hyptis is a declared Class B and Class C weed.

Another name for this plant is Hyptis suaveolens.

Hyptis - infestation 

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • annual or perennial
  • upright and branched herb
  • characteristic minty aroma
  • generally grow to 1 to 1.5m in height but can reach 2m.

Hyptis - habit 

Stems and branches

These features can identify the stems and branches:

  • stems are square shaped
  • young plants have green stems covered with fine hairs
  • mature plant stems are unlikely to exceed 0.5cm in diameter.

Hyptis - stems and branches 

Leaves

These features can identify the leaves:

  • hairy, opposite leaves
  • broad at the base with a pointed tip and toothed margins
  • size varies from 2.5-7cm long and 1-5cm wide.

Hyptis - leaves 

Flowers

These features can identify the flowers:

  • small
  • lavender-blue
  • occur in clusters in the leaf joints.

Hyptis - flowers 

Fruit and seeds

These features can identify the fruit and seeds:

  • seed capsule is green but dries to brown
  • each capsule has 5 stiff bristles
  • seeds are dark brown to black
  • seeds are shield-shaped and 3-3.5mm wide.

Hyptis - fruit and seeds 

Similar looking plants

The following plant species look similar to hyptis:

Knob weed (Hyptis capitata) can be distinguished from hyptis by its white spherical flower head (1.5cm diameter) on 5cm stalks. This is also a weed that should be controlled.

Impact

Hyptis can have all of the following impacts:

  • takes over improved and native pastures, especially when overgrazed
  • forms dense thickets
  • unpalatable to most livestock because of the aromatic oils.

Habitat and distribution

Hyptis is native to South America. It was first recorded in the NT in 1845 by the explorer Leichhardt, indicating it may have been introduced before colonisation.

It is now widespread in the Darwin, Katherine, Gulf and Victoria River districts.

It prefers disturbed areas such as roadsides and overgrazed areas. It will grow on most soil types, except those that become waterlogged.

Spread prevention

The small seeds stay in the spined burr/capsule that can be caught and transported by livestock, native animals and clothing. The capsules can float on water and can spread as a contaminant in hay or pasture seed.

You can prevent the spread of hyptis by doing all of the following:

  • map infestations to help develop a management plan
  • control minor infestations, isolated outbreaks or seedlings first
  • prevent cattle from overgrazing areas as this will create space for hyptis to spread
  • designate wash down areas and actively work to prevent contamination of clean areas
  • remove and burn new infestations on clean properties
  • monitor areas that you have treated and watch for re-infestations.

Hyptis - spread 

Control

Chemical control

The best time to treat hyptis is from December to March. Below is a list of chemicals and treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
2, 4-D amine 625 g/L
Various trade names
320ml / 100 L Seedling or adult (individuals or infestation):
Foliar spray - apply when actively growing
Glyphosate 360 g/L
Various trade names and formulations
15ml / 1 L Seedling or adult (individuals or infestation):
Foliar spray - apply when actively growing

Non-chemical control

Hand pulling and grubbing

Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Slashing

A brush-cutter, slasher or mower are used to cut weeds off above the ground level. This can be effective in suppressing flower and seed development.

Last updated: 27 June 2017