Scotland’s world-beating Amorphophallus titanum (titan arum) looks set to bloom for an incredible third time, prompting fresh opportunities for scientific, horticultural and entomological studies into this smelliest and most contradictory of plants at the Royal Botanic Garden Edinburgh (RBGE) – and calling-in strategies to ensure a warm welcome for considerably increased visitor numbers in the Glasshouses!
Both a celebrity – with its own social media following – and an enigma to everyone who knows it, the RBGE specimen continues to offer as many questions as answers to the leading scientists and horticulturists who have tended it for 17 years.
When the corm was last measured, in 2010, it weighed 153.9kg, making it the largest ever recorded. Research on the plant during two previous flowerings at RBGE – in 2015 and 2017 – gave the scientists in Edinburgh, working with counterparts in South East Asia, the information they required to ensure the species is now classified as Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Plants, through natural habitat loss.
The new bud emerged on May 12, exactly four years to the day from the first flower bud. When it first flowered, in June 2015, 19,000 people made their way through the Lowland Tropics House over four days days to see the spectacle.
Tropical Botanist Dr Mark Hughes, who specialises in the plants of SE Asia, said: “The Amorphophallus titanum only grows naturally on the Indonesian island of Sumatra. Its flowering here, at RBGE, for the third time symbolises our long-term commitment to the research and conservation efforts in that region.
“In the past five years our scientists have described 35 new species from Indonesian forests, showing how much remains to be discovered and protected for the future. This flowering provides an amazing opportunity to speak about the incredible plant diversity of the world.’’
The Amorphophallus titanum is a giant among plants, with a massive flowering structure that can rise some three metres above the ground. Even in its native Sumatra, its flowering is rare and unpredictable. The short-lived, night time bloom initially emits a pungent smell to attract pollinating insects such as carrion beetles and flies, hence the common name “corpse plant”.
Successfully bringing it to the point of flowering involves replicating the conditions it would experience in the rainforests. The Lowland Tropics House provides the required high humidity and temperatures. On two consecutive nights during flowering certain parts of the inflorescence heat up by 10 degrees centigrade. This heating coincides with the opening of first the female and then the male flowers, and helps to spread the smell and attract pollinators.
Glasshouse Supervisor Louise Galloway, whose team cares for the plant on a day-to-day basis concluded: “The Amorphophallus titanum can be difficult to grow to flowering stage and they usually take about seven to 10 years to reach maturity.
“Often after flowering and setting seed in the wild the plant’s energy is exhausted and it dies. We have been very lucky to have a stable corm, which has produced a consistent flower every two years since maturing.
“Its survival may be partly a result of it not being pollinated; however, our plants get a lot of TLC and, as a result, our corm has a circumference of 2.5m and a depth of nearly a metre. This massive energy reserve keeps it thriving and blooming successively. We have pollen stored and hope to pollinate successfully this time around.
“We are asking other botanic gardens what happens with their corm after blooming and setting seed. By sharing information, we hope to learn more about these increasingly rare and unusual plants and how the plants lifecycle can differ between growing in the wild and in cultivation.”
Sumatra is a key area of research and conservation work for RBGE scientists and horticulturists. Working widely with their counterparts in Southeast Asia they are making major impact on world knowledge of diverse tropical plant families.
On June 26 a significant representation of the research institute’s Tropical Team fly out to Universiti Brunei, Darussalam, for the 11th Flora Malesiana Symposium for international debate on the development of the taxonomic studies pivotal in understanding the incredible plant diversity of South East Asia.
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