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Scientific Name
Synonyms
Family
Common Names
Origin
Naturalised Distribution
Habitat
Habit
Distinguishing Features
Stems and Leaves
Flowers and Fruit
Reproduction and Dispersal
Environmental Impact
Legislation
Management
Similar Species
Print Fact Sheet
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Click on images to enlarge

large infestation (Photo: Land Protection, QDNRW)

infestation (Photo: Chris Gardiner)

habit prior to flowering (Photo: Sheldon Navie)

habit in flower (Photo: Sheldon Navie)

older plants with woody stems (Photo: Sheldon Navie)

deeply-lobed leaves (Photo: Sheldon Navie)

five-lobed leaf with tapered base (Photo: Sheldon Navie)

large flower-heads (Photo: Sheldon Navie)

bright yellow flower-head (Photo: Sheldon Navie)

old flower-head with young fruit beginning to develop (Photo: Sheldon Navie)

immature fruit (Photo: Sheldon Navie)

mature fruit (Photo: Sheldon Navie)

seedling (Photo: Sheldon Navie)

Tithonia diversifolia

Scientific Name

Tithonia diversifolia (Hemsl.) A. Gray

Synonyms

Mirasolia diversifolia Hemsl.

Family

Asteraceae (Queensland, New South Wales, the ACT, Victoria, Tasmania, Western Australia and the Northern Territory)
Compositae (South Australia)

Common Names

giant Mexican sunflower, Japanese sunflower, Mexican sunflower, shrub sunflower, tree marigold

Origin

Native to eastern Mexico and Central America (i.e. Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama). Despite its common name, this species is not native to Japan.

Naturalised Distribution

Japanese sunflower (Tithonia diversifolia) is widely naturalised in the coastal districts of Queensland and northern New South Wales. It is also present on Christmas Island.

Also widely naturalised throughout the tropical and sub-tropical regions of the world, including south-eastern USA (i.e. Florida and Texas) and several Pacific islands (i.e. the Cook Islands, the Galapagos Islands, Fiji, French Polynesia, New Caledonia, Niue, Palau, Western Samoa, Tonga and Hawaii).

Habitat

A common weed of roadsides, railway lines, creekbanks, disturbed sites, waste areas, embankments, hillsides and neglected suburban lots in tropical, sub-tropical and warmer temperate regions.

Habit

A robust and short-lived (i.e. annual) or long-lived (i.e. perennial) plant with upright (i.e. erect) stems forming shrubby bushes usually growing 2-3 m tall, but occasionally reaching up to 5 m in height.

Distinguishing Features

Stems and Leaves

The stems are slightly ridged (i.e. striate) and hairy (i.e. pubescent) when young.

The alternately arranged leaves are borne on stalks (i.e. petioles) 2-10 cm long. The leaf blades (6-33 cm long and 5-22 cm wide) have tapered (i.e. cuneate) bases and 3-7 pointed lobes with scalloped (i.e. crenate) or toothed (i.e. serrate) margins. These leaves are finely hairy (i.e. puberulent) and greyish-green in colour.

Flowers and Fruit

The large flower-heads (i.e. capitula) are borne in small groups at the ends of the leafy branches, on stalks (i.e. peduncles) 7-30 cm long. These flower-heads (5-15 cm wide) look like sunflowers, but have yellow centres (3-5 cm across). They have 7-15 bright yellow 'petals' (i.e. ray florets) that are 4-7 cm long and 9-16 mm wide, each with three small teeth at their tips. There are also numerous (80-120) tiny yellow flowers (i.e. tubular florets) in the centre of the flower-heads and they are surrounded by several rows of green bracts (i.e. an involucre). Flowering occurs during spring, but mainly during autumn and early winter (i.e. from April to June).

The 'seeds' (i.e. achenes) are 4-8 mm long and topped with a ring (i.e. pappus) of scales and two awns (about 5 mm long). These 'seeds' are covered in close-lying hairs (i.e. they are appressed pubescent), blackish in colour, and are somewhat four-angled.

Reproduction and Dispersal

This species reproduces by seed.

The seeds may be dispersed by animals, water and in clothing, They may also be spread in dumped garden waste and contaminated agricultural produce.

Environmental Impact

Japanese sunflower (Tithonia diversifolia) is regarded as an environmental weed in Queensland and New South Wales. It was also recently listed as a priority environmental weed in at least one Natural Resource Management region.

Legislation

Not declared or considered noxious by any state government authorities.

Management

For information on the management of this species see the following resources:

Similar Species

Japanese sunflower (Tithonia diversifolia) is similar to Mexican sunflower (Tithonia rotundifolia), wild sunflower (Helianthus annuus) and crownbeard (Verbesina encelioides). These species can be distinguished by the following differences: