Quick Facts

Quick facts

• Originally from the southern USA, Clockweed (Oenothera lindheimeri) is a perennial herb, with white turning to pink flowers, that grows in clumps to about 1.5 m high.
• It is very drought tolerant and has the potential to become an environmental weed.
• It has been planted in gardens and is spreading from seed into surrounding bushland areas.
• Unknown if it is a weed of agriculture.
• Control with foliar application of herbicides while actively growing.

What Does It Look Like?

What is it?

Clockweed (Oenothera lindheimeri) [as Gaura lindheimeri] is a many-stemmed and branched soft perennial herb which grows in clumps to about 1.5 m high. It has numerous slender, wiry stems which are covered with coarse hairs. The leaves are hairy and alternately arranged on stems, with a basal rosette (ground-level arrangement of leaves around the plant's central stem where it joins the roots) with or without a very short leaf-stalk. Leaves are elongated, 0.5–9 cm long and 0.5–1.5 cm wide with a tapering base, and the margins are wavy and often minutely toothed.

The flowers are zygomorphic (laterally symmetrical) and arranged in narrow inflorescence's (groups of flowers arranged along a stem) up to 80 cm long and are initially white but become pink as they age. The four petals (sometimes three) are 10–15 mm long, and joined at the base. Each flower has eight protruding stamens.

The fruit is a hairless strongly four-angled capsule that is 5–8 mm long, about 3 mm wide , containing 2-4  seeds (Western Australian Herbarium 1998; Harden 2007; VicFlora 2021).

For further information and assistance with identification of Clockweed contact the herbarium in your state or territory.

Flower colour

White, Pink

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Clockweed grows in grassland and grassy fields, in sand or clay, drainage pits, road verges and disturbed natural vegetation (Western Australian Herbarium 1998). It is drought and heat tolerant. This species has escaped from gardens around towns, and is present increasingly along roadsides (Southern Tablelands and South Coast Noxious Plants Committee undated).

Are there similar species?

Two species of Oenothera [as Gaura] are naturalised in Australia. 

Oenothera curtiflora [as Gaura parviflora] is an unbranched annual that is softly hairy and has symmetrical flowers with petals less than 2 mm long, whereas Clockweed is a branched perennial that is coarsely hairy and has asymmetrical flowers with longer petals (Western Australian Herbarium 1998; SGA undated).

Why Is It A Weed?

What are its impacts?

Clockweed has the potential to become an environmental weed (Southern Tablelands and South Coast Noxious Plants Committee undated).

Agriculture: Not yet known to be a weed of agriculture. However, as this is spreading along roads and from rural gardens, could spread in to poorly managed paddocks and horticultural crops.

Native ecosystems: At present it is mainly a weed of disturbed sites and roadsides close to where it has been cultivated, however it is also beginning to spread into more natural areas e.g. sandy sites and riparian zones (Queensland Government 2016). 

How does it spread?

Clockweed produces fine seed which is spread by wind (Southern Tablelands and South Coast Noxious Plants Committee undated).

What is its history in Australia?

Clockweed is grown in many gardens around Australia. It has become an occasional garden escapee around towns, and is present increasingly along roadsides (SGA undated).

How To Manage It?

Best practice management

Non-chemical control: In a garden environment, to prevent Clockweed from seeding it is important to cut the plant right back after flowering (SGA undated).

Chemical control: Can be controlled with broadleaf and other herbicides when applied as a foliar spray.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Clockweed is a perennial herb that dies down over winter and flowers from December to January. It produces prolifically amounts of seed (Western Australian Herbarium 1998; SGA undated).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, SA, VIC WA

What areas within states and territories is it found?

Clockweed occurs in New South Wales (Harden 2007), around Canberra in the ACT, the south-east corner of Queensland; around Melbourne in Victoria; in the Adelaide area and the south-east of South Australia, the south-west of Western Australia (AVH 2021; Western Australian Herbarium 1998).

Where does it originate?

Clockweed is native to southern parts of North America, from Louisiana, Texas (POWO 2021; USDA, 2021). 

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

Not declared in an states or territories. 

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Oenothera lindheimeri

Other scientific names (synonyms)?

Gaura lindheimeri Engelm. & A.Gray

Does it have other known common name(s)?

Clock-weed, Beeblossom, Gaura, Butterfly Bush