Why in news?
Observations by citizen scientists have shown that the Indian Laburnum tree is flowering earlier and for longer periods in many parts of India. Researchers attribute this shift to rising temperatures and changing rainfall patterns linked to climate change. The phenomenon is an example of how warming affects the timing of biological events, known as phenology.
Background
The Indian Laburnum (Cassia fistula), called Amaltas in Hindi, is a small to medium‑sized deciduous tree native to the Indian subcontinent and Southeast Asia. It grows to 10–12 metres tall with a spread of 10 metres. The tree bears pinnate leaves with pairs of oval leaflets and produces spectacular drooping clusters of bright yellow flowers. Because of its striking blooms, it is the state flower of Kerala and a symbol of prosperity in many cultures. Traditionally the tree flowers once a year between late spring and early summer, often coinciding with the Vishu festival in Kerala.
Observations and causes of phenological shift
- Earlier flowering: Citizen science platforms like SeasonWatch have recorded Amaltas trees blooming as early as February instead of the usual April–May timeframe.
- Prolonged blooming: In some regions the flowering period now extends over several months rather than a few weeks. Trees may produce a second flush of flowers later in the year.
- Link to climate change: Rising temperatures, erratic rainfall and urban heat islands are likely altering the cues that trigger bud formation and flowering. Warmer winters and pre‑monsoon showers can stimulate earlier growth.
Features and uses of the tree
- Ornamental value: The golden flowers appear in long, pendulous clusters up to 60 centimetres long, creating a spectacular display. The tree is commonly planted along streets and in gardens.
- Fruits and seeds: After flowering, long cylindrical pods develop, each containing many hard seeds. The pods are often used in traditional medicine, but the seeds are poisonous if eaten.
- Medicinal uses: Various parts of the tree are used in Ayurveda to treat skin diseases, constipation and fever. However, dosage and preparation must be handled carefully due to potential toxicity.
- Environmental tolerance: Amaltas is moderately drought‑tolerant and can withstand some salt and heat, making it suitable for urban landscapes.
Conclusion
Changes in the flowering behaviour of the Indian Laburnum remind us that plants are sensitive indicators of climate change. Monitoring such shifts helps scientists understand ecological responses and informs conservation planning. At the same time, the tree continues to delight people with its vibrant blossoms and holds cultural significance across India.
Sources: Mongabay, University of Florida IFAS