Cassia fistula, known as the golden shower tree and other names, is a flowering plant in the family Fabaceae, native to southern Asia, from southern Pakistan east through India to Myanmar and south to Sri Lanka. It is associated with the Mullai region of Sangam landscape. It is the national tree of Thailand, and its flower is Thailand's national flower. It is also state flower of Kerala in India and of immense importance amongst Malayali population. It is a popular ornamental plant and is an herbal medicine.

The golden shower tree is a medium-sized tree, growing to 10–20 m (33–66 ft) tall with fast growth. The leaves are deciduous, 15–60 cm (6–24 in) long, pinnate with 3–8 pairs of leaflets, each leaflet 7–21 cm (3–8 inches) long and 4–9 cm (1.5–3.5 in) broad. The flowers are produced in pendulous racemes 20–40 cm (8–15 in) long, each flower 4–7 cm diameter with five yellow petals of equal size and shape. The fruit is a legume, 30–60 cm (12–23 in) long and 1.5–2.5 cm (0.5–1 in) broad, with a pungent odor and containing several seeds. The seeds are poisonous. The tree has strong and very durable wood, and has been used to construct "Ahala Kanuwa", a place at Adams Peak, Sri Lanka, which is made of Cassia fistula ("ahala", "Ehela" or aehaela, ඇහැල in Sinhala ) heartwood.