Tip of the titan arum flower bud showing the emergence of the yellow spadix (15th June).

Being the largest flower head is one of the titan arum’s claims to fame. The Guinness World Record height for this species is an impressive 3.1 metres, so this Indonesian plant would seem to have a pretty strong claim to the crown. However, the devil is in the detail and we need to define what we mean by a ‘flower head.’

The first thing to say is that this massive structure is not a single flower. In fact, hidden at the base, behind the skirt-like spathe, are a large number of male and female flowers that mature at different times to reduce the chances of self-fertilisation. To a botanist a shoot that bears flowers and no leaves is an ‘inflorescence’ and it may support one to many flowers and take various forms. In some palms the inflorescence can be much longer than that of titan arum, but they are always branched so the titan arum can lay claim to the title of longest unbranched inflorescence in the plant world.

Herbarium specimen of titan arum collected by Odoardo Beccari showing the central spadix and the skirt-like spathe.

Getting any plant to thrive and ultimately flower involves replicating the conditions that it is adapted to in the wild. It is necessary to ensure that things like temperature, humidity, light level, soil moisture and soil nutrients are all within the range that the plant needs. Some plants are more fussy than others and keeping them happy becomes a real challenge. One reason that a titan arum flower is such big news is that getting the plant to flower in the first place is quite an achievement. The developing flower at the Botanics will be the first flowering of this species in Scotland, and is the result of 12 years of careful cultivation.

A brief history of New Reekie’s time:

• 2002 – Seeds sown at Hortus Botanicus Leiden in the Netherlands
• 2003 – Orange-sized corm (underground storage organ) sent to the Botanics
• 2010 – Corm weighed in at a record breaking 153.9 kg (not an official Guinness World Record)
• 2010 – Leaf cuttings taken to produce a new generation of young plants
• 2013 – Emergence of what turned out to be the last of seven leaves
• 2015 – Emergence of a flower bud on 12th May

The giant corm is potted in a 1,000 litre pot containing a compost mix including bark, pumice, sand, charcoal, perlite and slow-release fertiliser. As titan arum is a tropical forest species from Sumatra in Indonesia it is kept warm and humid at all times. The daytime temperature is in the region of 21-25 degrees centigrade, falling to around 19 degrees centigrade at night. High humidity is maintained by regular watering in the glasshouse.

Find out more at the Garden’s website.

The corm weighed in at a 153.9 kg in 2008 and is an unofficial world record weight for this species.