Cassia fistula belongs to the Fabaceae family just like Delonix regia; the genus Cassia contains about thirty different species all from tropical locations. Synonyms for this species can be Cassia rhombifolia and Cathartatocarpus fistulus.The genus Cassia was formerly grouped with plants nowadays in a different genus known as Senna which numbers 250 to 350 different species of trees, shrubs and herbaceous plants. Senna and Cassia can be differentiated by stamen shaped in‘s' shape and leaves void of glands for Cassia. The leaves in Cassia are pinnate (compound) and the twelve to sixteen leaflets are ovate.
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Impressive flowering Close-up of flowers Pinnate leaves

Known as "golden shower," "golden rain," "Indian laburnum," "purging cassia," "pluie d'or," "bâton casse," "caneficier," "faux sénné," "fleur cavadee," "lluvia de oro," and "chacara" this is a briefly deciduous tree which can grow to ten or twenty meters with a trunk up to one meter in diameter. It comes from deciduous low altitude dry forests areas (but has also adapted to somewhat rainy places) in south Asia and India but can still be found growing as high as 1300 m in the Himalayas. It is such a stunning tree when it is in full bloom that is can nowadays be found in most tropical countries, somewhat like the flame of the forest mentioned above; it is recorded since 1880 in Hawaii. The bright yellow vibrant flowers have seduced Thailand enough so that is has become the national tree.
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Same tree but in various locations...

Leaves are pinnate and alternate; they shed during the dry season. The very showy flowers come in drooping pendulous racemes (clusters) of scented luminous yellow up to thirty cm long or more. Individual flowers have five petals and ten stamens. The fruits appearing after pollination by insects (bees will visit) are long rounded black pods 40 to 60cm long and 2cm in diameter, considered by some people as good luck charms. They contain 40 to 80 shiny rounded seeds with a rather hard coat, they are toxic if ingested but nevertheless largely put to use for making necklaces and other ornaments. Those seeds are contained in a strongly scented black sticky sweet pulp which is used because of its natural laxative and vermifuge properties. Many ailments are treated with various parts of the plant in India, like bark for skin infections, leaves for rheumatism, pulp for bowel disorders as stated already, flowers as a purgative, etc. Ash from the leaves is put to use by mixing with magical herbs in Africa and Australia and is said to be effective in such special trade. The wood has a nice red color; it is quite strong and used in many ways such as props, carts and even for paving. It also makes good quality fuel. Bark is pale grey when the tree is young and turns dark brown with aging. It is used in parts of India for skin tanning.
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Long pods of various shapes showing seeds and pulp

You can grow your own Cassia fistula either from cuttings, layering or seeds. If you choose the seed way you will have to scarify them by using sulfur acid (to be washed thoroughly afterwards of course) and soaked in water for twenty-four hours before sowing. Those seeds have a quite long shelf-life of up to thirteen years at room temperature so keeping them refrigerated should allow to very long stocking if need be. You will need some patience as it usually takes eight to ten years between sowing and the first flowers to appear, the tree will thrive in zones ten to eleven. It is a fast growing species which required full sun and will do better in deep rich soil but can easily adapt to dry ones.
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Old cracked bark Elegant clusters

Blooming takes place at the end of warm season in the southern hemisphere (January to March) and between April and July in the northern hemisphere so make sure to check your world map before you set for travel and do not want to miss the spectacular flowering of Cassia fistula.