Cassia fistula aka Golden Shower Tree

Cassia fistula is a tropical tree in the pea family. Gardeners call it golden shower tree or Indian laburnum. Kew places its native range in western and southern India, plus Sri Lanka. Other garden sources extend this range into Southeast Asia. It grows in dry forests at low heights above sea level. People now plant it across the tropics for flowers and medicine. Useful Tropical Plants reports its conservation status as Least Concern.

Garden trees often reach 30–40 feet [9.1–12.2 metres] tall and wide. Some sources give heights of 50–66 feet [15.2–20 metres]. The crown may be narrow, spreading, or open at the top. Branches droop from a trunk that lacks thorns. Young bark is smooth and gray. It turns rough and brown with age. Green, pinnate leaves bear paired oval leaflets. The tree sheds its leaves for a short spell. Sources differ on growth speed, from slow to fast.

Yellow flowers hang in long racemes from the branch tips. Each flower has five petals and a light scent. The main display falls from May through early July. Broader reports span April to September, with another flush in early fall. Flowers can cover bare branches before new leaves grow. Butterflies visit the blooms, and insects pollinate them. Hard, round pods reach 1–2 feet [0.3–0.6 metres] long. They darken as they ripen and may hang through winter. Fallen pods and leaves can make a mess.

Grow this tree in full sun with soil that drains well. It accepts sand, loam, clay, and acid or alkaline soil. Give it moderate water; established trees can withstand some drought. Choose a site sheltered from drying winds. Hardiness reports range from USDA zones 10–12 to sheltered zone 9b sites. Frost can cause damage, though brief light frost may be survived. Young trees need pruning to build a sound crown. Gardens use it for shade, street planting, and as a specimen. Caterpillars, mildew, leaf spot, and root rot may occur.

Safety reports conflict, so food uses need caution. PFAF lists cooked young leaves, flower buds, flowers, and pod pulp as edible. That source also warns that all parts are poisonous when eaten. UF/IFAS warns that the seeds are poisonous. Pods and seeds have a history of use as laxatives. Bark also supplies dyes and tanning material.