golden shower tree

Cassia fistula
habit (Photo: Sheldon Navie)
habit with mature fruit (Photo: Forest and Kim Starr, USGS)
large compound leaves (Photo: Sheldon Navie)
close-up of large leaflets (Photo: Sheldon Navie)
leaflet undersides (Photo: Sheldon Navie)
drooping flower clusters (Photo: Sheldon Navie)
flowers showing three long stamens, four short stamens and three partially-formed stamens (Photo: Sheldon Navie)
older flower with cuved style and stigma (Photo: Sheldon Navie)
immature fruit (Photo: Sheldon Navie)
elongated mature fruit (Photo: Sheldon Navie)
close-up of opened mature fruit showing seeds (Photo: Forest and Kim Starr, USGS)
Tree
Alternate
Compound
Yellow
Green
Discoloured

A spreading tree that loses some of its leaves in the dry season. Its alternately arranged leaves (10-50 cm long) are once-compound with 3-8 pairs of relatively large leaflets. These leaflets (5-15 cm long and 4-9 cm wide) have bright green upper surfaces and paler undersides. Its bright yellow flowers are arranged in large elongated clusters (15-65 cm long) that hang downwards. These flowers (4-7 cm across) have five petals, seven fully-formed stamens, and an elongated ovary. Its large cylindrical pods (30-60 cm long and 1.5-2.5 cm wide) turn dark brown or blackish in colour as they mature.

Common names 
Also known as: golden shower tree, golden shower, Indian laburnum, pudding-pipe tree, purging cassia,
Family 
Caesalpiniaceae
Deciduous 
No
Flowering time 
Spring - Autumn
Native/Exotic 
Exotic
Origin 
Native to south-eastern Asia.
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

Naturalised in northern, central and south-eastern Queensland and near Darwin in the north-western parts of the Northern Territory.

Habitat 

A weed of riparian vegetation, open woodlands, wetland margins, roadsides, coastal environs and offshore islands.

Habit 

A spreading tree that loses some of its leaves in the dry season (i.e. it is semi-deciduous). It usually grows less than 10 m tall, but has the capability of reaching up to 20 m in height. Plants in Australia are often attacked by borers, and may be stunted or relatively short-lived.

Impact and control methods 

"In south-eastern Queensland, this species is occasionally a weed of riparian vegetation (i.e. along the Brisbane River in St. Lucia and along the Bremer River in Ipswich) and disturbed forests (i.e. on Coochiemudlo Island). It is also listed as a weed in Maroochy Shire on the Sunshine Coast.

Golden shower (Cassia fistula) is also regarded as an environmental weed in the Northern Territory, where it is actively managed by community groups. It has also spread from cultivation on Koolan Island and in the King Leopold Range in Western Australia."

Stem and leaves 

"The bark on younger trees in relatively smooth and greyish in colour, while the main trunks of older tress may be covered in rough, dark brown coloured bark. Younger stems are green and mostly hairless (i.e. glabrous).

The alternately arranged leaves (10-50 cm long) are once-compound (i.e. pinnate) and borne on stalks (i.e. petioles) 4-7 cm long. These leaves have 3-8 pairs of relatively large leaflets (5-15 cm long and 4-9 cm wide). The leaflets oblong, oval (i.e. elliptic) or egg-shaped in outline (i.e. ovate) with entire margins and pointed tips (i.e. acute or acuminate apices). They have bright green, hairless (i.e. glabrous), upper surfaces and paler, sparsely hairy (i.e. puberulent), undersides."

Flowers and fruits 

"The flowers are arranged in large elongated clusters (i.e. racemes), each cluster containing 20-75 flowers. These clusters (15-65 cm long) hang downwards (i.e. they are pendulous) and are borne on a stalk (i.e. peduncle) 2-10 cm long. The individual flowers (4-7 cm across) are borne on short stalks (i.e. pedicels) 3-7 mm long. Each of these flowers have five green sepals (about 9 mm long), which are folded backwards, and five bright yellow petals (18-40 mm long) that are distinctly veined. The flowers also have seven fully-formed stamens, three partially formed stamens (i.e. staminodes), and a slender elongated ovary topped with a style and stigma. Four of the stamens have stalks (i.e. filaments) 24-45 mm long, while the other three have stalks only about 5 mm long. Flowering occurs from spring through to early autumn.

The large, elongated, cylindrical pods (30-60 cm long and 1.5-2.5 cm wide) are hairless (i.e. glabrous) and do not split open when mature (i.e. they are indehiscent). These fruit turn from green to dark brown or blackish in colour as they mature and contain numerous (40-100) seeds embedded in a sticky, blackish-coloured, pulp. The seeds are pale brown in colour and about 8 mm across."

Reproduction and dispersal 

This species reproduces by seed, which may be spread by water and in dumped garden waste.

Similar species 

"Golden shower (Cassia fistula) is similar to some native species, including Leichhardt bean (Cassia brewsteri), brush cassia (Cassia marksiana) and velvet cassia (Cassia tomentella). These species can be distinguished by the following differences:

■golden shower (Cassia fistula) has relatively large petals (18-40 mm long) and the stalks of its stamens (i.e. filaments) do not have a swollen section. Its fruit are hairless (i.e. glabrous) and round in cross-section (i.e. terete).

■Leichhardt bean (Cassia brewsteri) has relatively small petals (5-20 mm long) and the stalks of its stamens (i.e. filaments) have a swollen section. Its fruit are hairless (i.e. glabrous), flattened (i.e. compressed), and distinctly ribbed.

■brush cassia (Cassia marksiana) has relatively small petals (5-20 mm long) and the stalks of its stamens (i.e. filaments) have a swollen section. Its fruit are hairless (i.e. glabrous), slightly flattened or round in cross-section (i.e. terete), and weakly ribbed.

■velvet cassia (Cassia tomentella) has relatively small petals (5-20 mm long) and the stalks of its stamens (i.e. filaments) have a swollen section. Its fruit are finely hairy (i.e. puberulent), and slightly flattened or round in cross-section (i.e. terete).