Shonalu or Golden shower tree (Cassia fistula, family: Fabaceae) is a medium-sized deciduous tree attaining a height of 8-10 m. This fast growing tree is native to South and Southeast Asia. As an ornamental flowering tree it is planted in gardens, parks and roadsides in Bangladesh as well as Asian countries.
Common names: Shonail, Shonalu, Bandor-lathi, Flame of the forest, Golden shower tree.
Leaves are compound, rachis 10-35 cm long. Leaflets are ovate, 8-15 cm long and 3-7 cm wide.
Flowers are yellow in pedunculate racemes, 40-50 cm long. Flower is showy, big, 4-6 cm across. Flowering season is early summer (April).
Fruit is a legume, 30-60 cm long, black in color. Pungent odorous fruit contains several seeds. Monkeys used to play with the sticky fruits of cassia fistula and for this reason the local people of Bangladesh called it Bandor-lathi (Monkey stick). Propagation of the plant is caused by seeds.
The gum, seeds and bark of cassia fistula are used in skin diseases and snake poison. Fruit is effective in constipation. It has strong and very durable wood. In Bangladesh, the tree is very renowned for its fabulous golden flowers. Cassia fistula is the national flower of Thailand.