Watsonia

Watsonia meriana var. bulbillifera

Family: Iridaceae

Type of weed:

Flower colour(s): , ,

Priority Weed Local Priority Weed. (See more weeds of the class.)

Flowering Months: , , , ,

Description

A long-lived, upright, herbaceous plant emerging each year from underground corms and growing up to 2m tall. Upright flowering stems are often reddish.

It has very large strap-like leaves. Most of the leaves arise from the base of the plant.

Tubular flowers are widely spaced along the flower spike. Flowers orange, red or salmon pink with six fused ‘petals’, in spring and early summer.

Fruit and seeds are generally not produced in Australia. Instead, clusters of small reproductive structures (bulbils) are produced at the upper stem joints.

Don’t confuse with…

Watsonia can be confused with native Dianella spp. and the weed Montbretia. (Under the ground Montbretia has long strings of corms which break away when the parent plant is disturbed and begin to shoot.)

Dispersal

It spreads vigorously by underground ‘bulbs’ (corms) and smaller ‘bulbs’ (bulbils). Corms are washed downstream. It is dispersed by the movement of soil containing corms and in dumped garden waste.

Impact on bushland

Watsonia displaces native understorey plants. Concentrations of the plant create a fire hazard in summer.

Distribution

, . Particularly Upper Mountains.

Alternative planting

Native plants

  • Native Water Ferns (Blechnum spp.)
  • Dianella spp.
  • Native Saw Sedges (Gahnia spp.)

Council provides a tool, on its Mountain Landscapes website, to help you choose native alternative plantings. Choose your village, soil, vegetation community and the purpose of your planting, and the tool will give you suggestions.

There are native nurseries in several Blue Mountains villages, including Glenbrook, Lawson and Katoomba. Please also ask at your favourite local nursery.

Control

  • Manually remove bulbs, corms and tubers
  • Spray
  • Stem swipe

Manual control

Manual removal

Move leaf litter away from base of plant. Dig down next to the stem until the bulb or tuber is reached. Remove plant and carefully bag the bulb or tuber.

Chemical control

Note: Herbicides that may be used for this weed include Glyphosate.

Spraying

Please consult the Herbicide page of this website to help you decide whether to spray, how to do it safely and more.

Extra considerations for weeds with underground reproductive structures
  • Further digging may be required for plants with more than one tuber. Some bulbs may have small bulbils attached or present in the soil around them. These need to be removed. It may be quicker and more effective to dig weeds out.
  • Learn and understand how the herbicide works. For bulb and corm species the most effective time is after flowering and before fruit has set.

Stem swiping

Using adapted tongs with sponge tips to swipe leaves with glyphosate
Montbretia swiping

As always with poisons, see the Herbicide page for information about when to use herbicides — and how to use them effectively and safely.

This method is suitable for herbaceous plants with bulbs, tubers or corms (See Montbretia fact sheet).

Bushcare has produced an instruction page to make your own wiper. Download a PDF with instructions on making and using the wiper.

  • Using a weed wiper, start at the base and wipe all the stems and/or leaves with a dilute mix of herbicide. For more information see the Using_Your_Wiper PDF.
  • If leaves have soil on them, wipers must be washed regularly.

Take great care when wiping: do not allow the herbicide to touch your skin or to run off into the soil, or to get on a non-target plant. Wear safety glasses to avoid being splashed.

Specific control tips for this weed

  • Dig out corms and remove flowering stems which carry bulbils (spring to summer).
  • Bag and remove all corms and bulbils, or bag and remove all stems with bulbils.
  • Wipe leaves with herbicide between flowering & fruiting (summer).
  • In open areas away from tree roots and swamp vegetation, spot spray with herbicide.

For key points on these techniques:

Local Priority Weed

Control measures:

  • The plant should be fully and continuously suppressed and destroyed.
  • Plants under 4 metres in height should be fully and continuously suppressed and destroyed.
  • The spread of this plant should be adequately contained to prevent spread impacting on priority assets. Weed notices will only be issued for these weeds under special circumstances.

For more info

For key points on these techniques:
  • Gloved hand using adapted tongs with sponge to wipe herbicide onto leaves

    Montbretia wiping