A giant leafAfter flowering, the inflorescencedies back and in its place a singleleaf emerges. Reaching the size ofa small tree, up to 6m tall and 5macross, the leaf consists of a sturdyglossy green stalk mottled withcream which divides into three at itsapex and bears numerous leaflets.Sugars made in the leaf aretransported back to the tuber forstorage as starch. The old leafwithers before a new one develops,using the tuber’s energy stores.Eventually another inflorescenceemerges, growing upwards at a rateof some 10cm per day.

How are the flowers pollinated?At the base of the spadix, withinthe protective chamber formed bythe spathe, is a band of cream maleflowers above a ring of the largerpink female flowers. When theflowers are ready for pollination,the spadix emits a nauseatingsmell that attracts the pollinators.This stench, described by some asa mixture of rotting flesh andexcrement, is so bad that theIndonesians call the plant ‘the corpseflower’. At one time, it wasrumoured that elephants pollinatedthe flowers, but beetles weregenerally thought to be responsible.Recent observations suggest thatthe insects which transfer pollenbetween the giant inflorescencesare carrion flies.

Information sheet O10

A blooming giantThe massive inflorescence consistsof a bell-shaped spathe, up to threemetres in circumference, with ribbedsides and a frilled edge, around acentral spike-like spadix. On theoutside, the enveloping spathe isgreen speckled with cream, but itsinterior is rich crimson. At its base,the spathe forms a chamberenclosing the flowers which arecarried at the lower end of thegreyish-yellow spadix.

The inflorescence arises from anunderground tuber, a swollen stemmodified to store food for the plant.This tuber, more or less spherical inshape and weighing 50kg or more, isthe largest such structure known inthe plant kingdom.

One of the most spectacular plants to be found in the wettropics zone of the Princess of Wales Conservatory is the Titan Arum (Amorphophallus titanum). With its huge floweringstructure (inflorescence) rising some three metres above theground and its single immense leaf, it certainly is a giantamong plants, as its name suggests.

Titan Arum

The Titan Arum that flowered

at Kew in 1996 reached

nearly 3m in height

Titan Arums can also be propagatedfrom leaf cuttings.

They are grown in the wet tropicszone of the Princess of WalesConservatory. During the day, thetemperature is kept at a minimum of21ºC and at night it drops no lowerthan 16ºC. The humidity ismaintained at 70% or above –mimicking the conditions prevailingin the plant’s original rainforesthabitat. The plants are fed regularlywith a high phosphate fertiliser.

They are repotted while dormant.In winter 2004, the largest tuber,now in a 1,000L pot, weighed anastonishing 91kg (200 lb or14 stone). This plant flowered inMay 2005.

HistoryThe Titan Arum originates in themoist shaded rainforests of Sumatra.The first European botanist toencounter it was the Italian, OdoardoBeccari, who was travelling in theregion in 1878. He sent back seeds tohis patron in Italy and one of theyoung plants that germinated fromthem was subsequently dispatched to Kew, where it flowered in 1889,exciting great public interest. In 1926,

© Copyright 2006, Board of Trustees Royal Botanic Gardens, Kew

Information sheet O10

www.kew.org

when it flowered again, the crowdsattracted by the phenomenon wereso large that the police were calledto control them.

When the plant in the Princess ofWales Conservatory flowered in 1996, a scientist from Kew’s JodrellLaboratory investigated theobnoxious smells that it produced.The strongest smells occurred on two consecutive evenings, firstlywhen the female flowers were readyfor pollination and then when themale flowers were ready to shedtheir pollen. Analysis of a sample of the odour identified two sulphur-containing chemicals. A similarsulphurous compound is responsiblefor the smell of rotten eggs.

More information The Private Life of Plants by DavidAttenborough (BBC Books, 1995)

Aroids: Plants of the Arum Family byDeni Bown (Century Hutchinson,2000)

The Genera of Araceae by SimonMayo, Josef Bogner and Peter Boyce(Royal Botanic Gardens, Kew, 1997)

The flowering of the Titan Arum draws

huge crowds to Kew

Female flowers are receptive for one night

only. The male flowers, above them, produce

pollen the following day to avoid self-

pollination. Hand pollination is difficult and

must involve two inflorescences flowering in

perfect sequence or the use of frozen pollen.

The giant leaf

Attracted by the light colouration atits base, the flies enter the spathechamber, and any pollen that theyare already carrying brushes off onto the female flowers. When theyleave the flower they are dusted with pollen and fly off in search of another stinking inflorescence. As the plants rarely grow in closeproximity to one another, the giantinflorescence is thought to beessential for dispersing the scent over large areas to attract pollinators.

From the pollinated female flowers,the fruits develop inside the spathechamber. Once they are ripe, thespathe withers completely exposingthe bright scarlet fruits. These attractthe attention of hornbills and otherbirds that eat them and disperse their seeds.

Kew’s Titan ArumThe Titan Arums displayed in thePrincess of Wales Conservatory weregrown from seeds sown in 1995.It takes six years for a seed-grownplant to reach flowering size.