Quick Facts

Quick facts

• Tropical Buttonweed (Diodia sarmentosa), a native of the African and American tropics, is a scrambling herb with a tap root.
• It is a strand plant (generally found in beach ecosystems between the ocean and the land), often found near the high water mark, also growing in grassland and bushland at low altitudes.
• It is dispersed by seed.
• It is not currently naturalised in Australia, but is a weed of cultivation in other countries.

What Does It Look Like?

What is it?

Tropical Buttonweed (Diodia sarmentosa) is a scrambling perennial or annual herb with a tap root. Its stems are 1–4 m long, often with numerous lateral branches, square in cross-section with long hairs on the angles. Its leaves grow in opposite pairs and are yellowish-green, lance-shaped, 1.8–6.3 cm long and 0.7–2.8 cm wide. The upper surface of the leaf is rough to the touch with dense hairs, and the underside is smooth. The leaf stalk is 1–5 mm long.

Flowers occur in clusters of 1–8 at most nodes. Each flower is 1.5–3 mm long with four mauve or white petals, somewhat hairy on the outside.

Fruits are up to 3.5 by 2.5 mm and the seeds are dark blackish red, and 2–4 mm long by 1.5 mm wide (Hyde & Wursten 2002-8; PIER 2008).

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

Flower colour

White, Purple

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Tropical Buttonweed is a strand plant (generally found in beach ecosystems between the ocean and the land), often growing near the high water mark. It grows in grassland and bushland at low altitudes, and it is a weed of cultivation (PIER 2008). In Zimbabwe, it is found at the margins of evergreen and riverine forest and rocky areas near rivers (Hyde & Wursten 2002-2008).

Are there similar species?

Tropical Buttonweed is one of eight species in the genus Diodia. Only Diodia teres is recorded as occurring in Australia. Diodia teres is a spreading or ascending herb growing to 40 cm high. Its flowers are in clusters of 2 or 3 and are white, pink or mauve (Harden 2007). These two species may be hard to distinguish. Please contact the herbarium in your state or territory for further identification.

Why Is It A Weed?

What are its impacts?

Agriculture: Tropical Buttonweed is an important weed in Africa and India. It is also a weed of coffee, tea and Leucaena plantations in Indonesia (PIER 2008).

How does it spread?

Tropical Buttonweed disperses by seed (PIER 2008).

What is its history in Australia?

Tropical Buttonweed is not currently naturalised in Australia.

How To Manage It?

Best practice management

No information is available on control of Tropical Buttonweed.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Tropical Buttonweed is a perennial (BayScience Foundation 2004-2008).

Where Is It Found?

Which states and territories is it found?

Not currently naturalised in any Australian state or territory

What areas within states and territories is it found?

Tropical Buttonweed is not currently naturalised in Australia.

Where does it originate?

Tropical Buttonweed is widespread in tropical Africa, Asia, and America (GRIN 2008; Hyde & Wursten 2002-2008).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT

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

Diodella sarmentosa

Other scientific names (synonyms)?

• Diodia breviseta Benth.
• Diodia littoralis Peyr.
• Diodia pilosa Schumach. & Thonn.
• Diodia riparia Sagot ex K.Schum.
• Diodia sarmentosa var. bisepala Bremek.
• Spermacoce pilosa (Schumach. & Thonn.) DC.
• Spermacoce radula Willd. & Hoffmanns. ex Roem. & Schult.