A natural heater hidden in India’s ‘sacred lotus’ flowers
The ‘sacred lotus’ plant is native to North and Central India and grows in ponds, lakes and slowly flowing water. | Photo Credit: T. Voekler (CC BY-SA)
Thermogenesis is the name given to the way living things create their own body heat. While we often think of only birds and mammals as warm-blooded, all complex life forms produce some heat. Tiny power plants in cells called mitochondria convert food into adenosine triphosphate (ATP), a biofuel. But only a quarter of the energy in your food actually turns into ATP; the rest escapes as heat.
Sometimes mitochondria can convert all the energy in sugars into heat. The enzyme that can do this in plants is even called alternative oxidase. But only a few plants produce heat for very clever uses.
‘Sacred lotus’ plant (nelumbo core)It is native to Northern and Central India and grows in ponds, lakes and slowly flowing water. Flowering begins in early summer at mild ambient temperatures. The beautiful flower blooms for three to four days. During this period, the internal temperature of the flower is around 30-35°C, but the environmental temperature can drop to 10°C.
Thermogenesis is triggered when the petal tips of the unopened flower turn pink. The flower, which opens early the next day, radiates heat, which helps spread an attractive scent. The lotus flower has a central cone-shaped chamber, and the flat top of this chamber contains 10-30 female organs, namely pistils. As in other thermogenic plants, the pistils mature first. The scent attracts pollinating insects (bees and beetles) to its receptive pistils. The leaves close at noon, creating a cozy, insulated room for insects to shelter in for the night.
Before the flower opens on the second morning, the stamens, the male organs of the flower, mature. Insects that feed on pollen and become covered with it fly away and move to other recipient plants. The system was designed to enable cross-pollination between plants; This offers many advantages to their offspring, including greater genetic diversity and increased pest resistance. Each pistil grows into a lotus nut, and the chamber matures into a showerhead-shaped seed pod.
The flat top where the pistil is located is approximately 4-5°C warmer than the rest of the flower. Calcium ions act as an ‘on’ switch. When it is time to warm up, the calcium level in the cells in this area increases fourfold. This calcium travels to the mitochondria and signals them to shift into high gear. Large amounts of stored starch and fat are used to generate heat (Plant Physiology198, 2025, kiaf173).
Some plants of the Arum family also use thermogenesis to attract insects and other strange purposes. Eastern skunk cabbage, not related to cabbage, grows in colder regions of North America and gets its name from its skunk-like odor, with a hint of mustard. The flowering stem of this plant emerges in early spring, producing heat to melt the snow covering the soil. Insects find warm respite in this flower along with pollen. Even spiders notice insect traffic and weave their webs near the flower.
A putrid smell is associated with the flowers of the dead horse arum lily, found in Geranium. This herb uses heat to strongly disperse compounds such as dimethyl disulfide, which smells like a leaky gas cylinder with a garlicky odor at the top. Scavenger flies find this smell completely irresistible and come in large numbers.
(The article was co-authored with Sushil Chandani, who works in molecular modelling.)
It was published – 23 January 2026 05:30 IST
