Cassia fistula

Common name: Shower of gold

Other common names: Golden shower, Indian laburnum, Indian senna, Pudding pipe tree, Purging cassia

Names in non-English languages: India Spanish

Description

Shower Of Gold is a spectacular flowering tree originating in India, its distribution scattered over most of the subcontinent, where it occurs in both dry and moist deciduous forests. 

It is typically 10 to 15 m (30 to 50) tall, usually with a single trunk, though is occasionally multi-trunked, and develops a moderately branched crown of variable shape, from narrow to round or wide-spreading, depending on the growing conditions. The bark smooth and yellowish when young becoming dark grey, cracked and flaking off in patches on older trees.

The leaves are large and feather-like, made up of medium-green, oval leaflets arranged in opposite pairs along the length. Most fall from the tree in the dry season, leaving the branches bare until the start of the rainy season when the new leaflets emerge, which are at first copper-coloured and softly hairy.

While the new leaves are emerging the tree bursts into bloom, producing masses of bright yellow flowers held in long, hanging clusters. They are followed by thin, round cigar-shaped seedpods up to 70 cm (2.3 ft) long. Near black when ripe, they persist unopened on the tree for months.

Use

It is commonly cultivated in gardens and landscapes, including streetscapes and in coastal areas for its showy flowering and tolerance to salt spray.

It produces a heavy wood, averaging out at around 800 kgs per cubic meter with brick-red heartwood and moderate natural resistance to decay. Although this puts it in the durable hardwood class, the logs mostly come in diameters too small for sawing into planks. The roundwood is cut for poles and posts, turnery, tool handles, firewood and is made into charcoal.

The fresh-cut leaves are palatable to livestock and nutritious, with a dry weight protein content of around 17%.

The bark is a source of tanning in India traded under the name 'Sumari'.

Health use

In some parts of its native range the bark is stripped and prepared for use in medicines as a purgative.

Climate

Grows and flowers reliably in sub-humid to moderately humid subtropical and tropical lowland to mid-elevation climates, generally in areas with annual lows of 15 to 25 °C, annual highs of 22 to 35 °C, annual rainfall of 700 to 2300 mm and a dry season of 8 months or less.

Growing

New plants are usually grown from seed which remain viable for months when dried and stored under cool, dry, airtight conditions. Germination is improved by soaking the seed in pre-boiled, hot water for five minutes prior to planting. Growth is best on free-draining sand and loam soils of a slightly acid to neutral nature, generally with a pH of 6.0 to 7.0 and on sites with full- to partial-sun exposure.

Problem features

Reports on its weediness are conflicting. It is assessed as a low weed risk species for Hawaii and Florida, respectively by the Hawaii Pacific Weed Risk Assessment project (HPWRA) and the IFAS Assessment of Non-Native Plants in Florida's Natural Areas. However, in Australia it is recorded as a weed of agriculture, a serious weed class.

In India, it is reported as a major source of irritating pollen that contributes to causing hay fever in some people. The roots are moderately vigorous and a minimum planting distance of six meters from underground pipes is recommended.

Where it will grow

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