Its drooping clusters of bright fragrant yellow flowers with five petals and characteristic cylindrical fruits, the Amaltas is known by so many names — Indian Laburnum, Golden Shower, Purging Fistula, Pudding-pipe tree, Girmala, Rajbrikh, Alash, Kiar, Kirwara, Ali — showing us how common and loved it is. It is both the national tree and the national flower of Thailand and is also the state flower of Kerala.
The Amaltas ( Cassia fistula linn ), native to South-East Asia is one of the most widespread trees in India and South-East Asia, with their presence both in cities as well as in moist and dry forests. The tree is mostly known to be ornamental and few know of its benefits as a medicinal plant, and one that’s loved by some mammals, bees, and butterflies (it plays host to the Lemon Emigrant).
This middle-sized deciduous tree is leafless only for a brief time, between March and May. The new leaves are glossy, a trait that they lose on maturing, and are mostly bright green, though sometimes a rich copper too. It flowers from April to June, partly alongside the emergence of new leaves, but it’s not uncommon to find the Amaltas in flower as late as September.
The bark is yellowish at first, slowly coarsens with age and turning dark grey. The naturalist in me made me open one of the seed pods that ripen in April, only to discover the seeds in small compartments surrounded by a strong-smelling pulp, which was sweet to taste.
Considering the fruit’s hard exterior (someone jokingly threw it at me once!) what bewildered me, when I was a young naturalist, was how the seeds were dispersed. The answer came much later, when I read British forestry expert Robert Scott Troup’s book Silviculture of Indian Trees (published in 1921). He had carried out an interesting experiment in 1911, around pollination of the Amaltas and jackals in the vicinity. He merely collected ripe fruit pods from the tree and placed them at a plot picked randomly. These were discovered by a pack of jackals a week later, who were found trying to get to the sweet pulp inside the pod.
With the natural reproduction of the tree being somewhat of a mystery, Troup went to the length of stating that “the reproduction of Amaltas is effected mainly, and perhaps entirely, through the agency of animals like monkeys, jackals, bears, pigs and a few others, that break open the pods to eat the pulp and thus scatter the seeds or swallow them and disseminate them via their excreta.”
Troup worked at what was then the Imperial Forest Research Institute and College at Dehradun ( now Forest Research Institute, Dehradun). Later in 1920, he returned to England to join the University of Oxford as the Chair of Forestry. His book, in three volumes, containing detailed silviculture accounts of several important trees of the Indian Subcontinent.
Considering the dearth of jackals in the city, I have only observed Neelgais feeding on the leaves of the tree, but not the fruit. I’ve observed several specimens of this tree (Aravalli Biodiversity Park, Vasant Kunj) with chew and nibble marks around the lower end of the bark near the roots, suggesting porcupine presence. The bark is used to make dye and the pulp in the fruit pod also serves as a strong purgative agent, which also helps animals that feed on it. A medicinal preparation with the roots of the tree is used to cure leprosy and skin diseases and the leaves are used to get rid ulcers, in traditional medicine.
Many years ago, when I had spoken to villagers on the outskirts of Delhi, they told me that they place these seedpods in the house to keep bedbugs and insects at bay, though we have no scientific evidence of this.
The writer is the founder of NINOX - Owl About Nature, a nature-awareness initiative. He is the Delhi-NCR reviewer for Ebird, a Cornell University initiative, monitoring rare sightings of birds. He formerly led a programme of WWF India.
