After two consecutive years of incessant rains, floods and landslides in the month of August, the smallest district in Karnataka, Kodagu, was in for a surprise this year.

The famous Neelakurinji flowered gregariously across a few hills. It soon caught the media’s attention and both tourists and local residents thronged the hills of Kotte Betta and Mandalpatti to take in the beautiful sight. After the 2018 mass flowering in Kerala, this was the first time that Neelakurinji was blooming on a large scale.

Social media buzzed with photos of tiny blue flowers that had flowered in unison, unrolling a breathtaking lilac carpet across the hills. Private tour companies rose to the occasion and went all out to help tourists get a glimpse of the rare event, even making choppers available for those who were willing to spend to get an aerial view of the bloom that happens once in a blue moon.

National media too caught on to the news and it was reported widely that the flower is the neelakurinji (Strobilanthes kunthiana) that blooms every 12 years at many places across the Western Ghats but most famously in the high ranges of Kerala. Botanists, however, differed, saying the Kodagu mass bloom is another species of Kurinji belonging to the same Strobilanthes family, Strobilanthes sessilis var sessiloides (a sub-species of Strobilanthes sessilis) which blooms once in seven years.

Both S sessilis and S kunthiana are grassland species but isolated to different altitudes – S kunthiana occurs in grasslands of above 1,500 metres whereas S sessilis occurs in the grasslands below 1,200 metres.

Marked by diversity

Local residents of Kodagu were baffled at the sudden attention to an occurrence that they have grown up seeing. “Neelakurinji flowers bloom in my cardamom estate too but a lighter blue flower than the ones flowered in Mandalpatti,” Said Bettathoor resident Kountinya Thammaiah. “The last time I saw a flowering in my estate was eight years ago. It is likely to flower again in the next few years. It is not unusual to see these flowers.”

This casual spotting of a monocarpic plant is best explained by its species variety, said Kerala-based botanist Jomy Augustine who has been tailing this flower for the last 25 years to study the species. “Kodagu has three species of Strobilanthes that are endemic to the district,” Augustine said. “You will not find these species anywhere else in the world.”

The other two species endemic to Kodagu, Strobilanthes carnatica and Strobilanthes canaricus, flower once in four years. Apart from them, there are other species that bloom occasionally. “Sometimes, species like S sessilis have rhizomatous rootstock from which new shoots come up every year as a natural way to get rid of fire events but giving a perennial appearance to the plant,” he said.

Neelakurinji in bloom. Photo credit: Abhishek N Chinnappa

Karnataka is home to many Strobilanthes species. Two species that flower in Pushpagiri wildlife sanctuary are named S Pushpagiriensis and S Lakshminarasimhanii. In 2019, the journal Plant Science Today published a study that revealed two new species in Karnataka, S mullayanagiriensis and S bislei, both take eight to 16 years to reach maturity. S mullayanagiriensis borrows its name from the Mullayanagiri peak of the Baba Budan Giri Hill ranges where the plant commonly grows whereas S bislei is found in Bisle Ghat in Hassan, a biodiversity hotspot that is a part of the central Western Ghats.

A shrubby flowering plant that belongs to the family Acanthaceae, Strobilanthes is the second largest genus in the family. Among various unique characteristics, species diversity sets Strobilanthes apart. The genus comprises about 350-400 species and the Indian subcontinent has more than 150 species. It is second in diversity in plants, next only to Balsams (Impatiens) which has over 1,000 species recorded, said Augustine. This also makes it difficult for ordinary flower enthusiasts to keep track of this amazing plant species.

Western Ghats’ biodiversity

The Western Ghats is the hotspot of Strobilanthes with 99% of all species found in India being endemic to the Ghats, said Augustine. “Western Ghats has about 66 species-67 species endemic to the region. We do not get to see four-five species which are believed to be extinct but one cannot be sure,” he said.

Augustine dedicates the plant’s species diversity to its ability to evolve and adapt. Since the plant species is hugely dependent on microclimatic conditions, the blooming of Neelakurinji in the Western Ghats is an indicator of its habitat diversity and presence of specific microclimatic conditions that are congenial to the survival of rare species of plants like Strobilanthes.

The Nilgiris (or the “blue mountains”), which takes its name from the blue Kurinji flowers, perhaps have the most number of species in the Western Ghats. Restoration ecologist in the Nilgiris, Godwin Vasanth Bosco said that the Nilgiris has more than 60 species of which 10-15 are endemic and some of them are endangered.

Augustine said that Kerala has 45 species to its credit of which 41 species are endemic to the southern Western Ghats, most of which are seen in evergreen forests and shola forests above 1,000 metres altitude. “The largest protected area in Kerala Periyar Tiger Reserve is with 23 species including S kunthiana and Eravikulam National Park has at least 18 species,” Augustine said.

Strobilanthes sessilis var sessilioides. Photo credit: Abhishek N Chinnappa

The different shrubby species of Strobilanthes grow vegetatively for three to 15 years and attain one to seven metres of height. They reach the reproductive stage in between four and 16 years at the end of their life span, burst into synchronised blooming, and cover the entire hill range or the area where they occur.

The flowers of Neelakurinji turn to fruits and seeds and the plants dry up after the distribution of the seeds in the same year. The seeds germinate and grow into seedlings about 700 per sq metre in the following monsoon. Those that survive environmental challenges fall asleep, growing silently and continuously, preparing themselves physically and physiologically for the next floral celebration.

Scientists, however, warn that mass blooming of Strobilanthes and synchronous flowering of various species can have several ecological consequences which need to be studied more thoroughly. The mass death of the plants after flowering produces enormous combustible material within and around the shola forests which are very susceptible to forest fires.

A fire can destroy the dispersed seeds, the paper titled Special Habitats and Threatened Plants of India noted. Marked by its monocarpic nature, gregarious flowering, seeding and then dying en masse, Strobilanthes, said Augustine, plays a major role in stopping soil erosion during rainy seasons in hilly areas where they bloom. “But if the rains happen during their wilting phase, it paves way for increased erosion,” he said.

Rare occurrence

Despite the species variety, why do are mass blooms, a characteristic of the species, so rare now? Has climate change got anything to do with it?

“The last big bloom happened at Eravikulam National Park in 2018,” said KA Sreejith, who is the principal investigator of a study on the species at Kerala Forest Research Institute. “The disastrous Kerala floods also happened around the same time. We are monitoring the plant here to develop a base level map to understand the species better.”

He said he believes the study will give a better understanding of the effect of climate change and other variables on the species and also get an idea of what effect natural disasters like floods can have on its phenology.

An Indian blue mormon (Papilio polymnestor polymnestor). Photo credit: Abhishek N Chinnappa

Researchers agree that grassland conservation is paramount to conserving many Strobilanthes species. Grasslands, a dynamic vegetation that possesses multiple ecological niches and hence more species diversity, are in fact the cradle of Neelakurinji. The popularity of the flower also inspired conservationists in Kerala to put forward an appeal to the government to conserve the habitat of S.kunthiana that resulted in declaring a 32 sq km grassland area in the region called Kurinjimala (a mountain for Kurinji) as a sanctuary in 2006.

“In the Nilgiris, only 10% of the original shola grassland is left,” said Bosco. “Habitat loss is one of the prime reasons why Strobilanthes is not seen as much as before. Road networks that make way for invasive species push the endemic ones away.”

Augustine squarely blames it on altering grasslands for plantations and in the name of tourism. He said various land-use changes contribute to habitat loss.

“Native forest exploitation in the name of tourism is much less in Karnataka compared to Kerala or Tamil Nadu,” shared Augustine, giving us hope that we may continue to see the hills of Kodagu wear the blue cape every few years.

This article first appeared on Mongabay.