Amorphophallus titanum

Amorphophallus titanum derives its name from Ancient Greek (άμορφος – amorphos, "without form, misshapen" + φαλλός – phallos, "phallus", and titan, "giant"). The popular name "titan arum" was coined by W.H. Hodge.[2]

Two titan arum in Sumatra, Indonesia (ca. 1900–40); one in leaf, which can reach up to 6 m (20 ft) tall, and one in bloom

The titan arum's inflorescence can reach over 3 metres (10 ft) in height. Like the related cuckoo pint and calla lily, it consists of a fragrant spadix of flowers wrapped by a spathe, which looks like a large petal. In the case of the titan arum, the spathe is a deep green on the outside and dark burgundy red on the inside, with a deeply furrowed texture. The spadix is hollow and resembles a large baguette. Near the bottom of the spadix, hidden from view inside the sheath of the spathe, the spadix bears two rings of small flowers. The upper ring bears the male flowers, the lower ring is spangled with bright red-orange carpels. The "fragrance" of the titan arum resembles rotting meat, attracting carrion-eating beetles and flesh flies (family Sarcophagidae) that pollinate it. The inflorescence's deep red color and texture contribute to the illusion that the spathe is a piece of meat. During bloom, the tip of the spadix is approximately human body temperature, which helps the perfume volatilize; this heat is also believed to assist in the illusion that attracts carcass-eating insects.

Both male and female flowers grow in the same inflorescence. The female flowers open first, then a day or two following, the male flowers open. This usually prevents the flower from self-pollinating.

After the flower dies back, a single leaf, which reaches the size of a small tree, grows from the underground corm. The leaf grows on a somewhat green stalk that branches into three sections at the top, each containing many leaflets. The leaf structure can reach up to 6 m (20 ft) tall and 5 m (16 ft) across. Each year, the old leaf dies and a new one grows in its place. When the corm has stored enough energy, it becomes dormant for about four months. Then the process repeats.

Small corm of A. titanum, Muttart Conservatory, Edmonton, Canada

The corm is the largest known, typically weighing around 50 kg (110 lb).[3] When a specimen at the Princess of Wales Conservatory, Kew Gardens, was repotted after its dormant period, the weight was recorded as 91 kg (201 lb).[4] In 2006, a corm in the Botanical Garden of Bonn, Germany was recorded at 117 kg (258 lb),[5] and an A. titanum grown in Gilford, New Hampshire by Dr. Louis Ricciardiello in 2010 weighed 138 kg (305 lb).[6][7] However, the current record is held by a corm grown at the Royal Botanic Garden Edinburgh, weighing 153.9 kg (339 lb) after 7 years' growth from an initial corm the size of an orange.[8]

Amorphophallus titanum is native solely to western Sumatra, and western Java where it grows in openings in rainforests on limestone hills.[9] However, the plant is cultivated by botanical gardens and private collectors around the world.[1]

The titan arum grows in the wild only in the equatorial rainforests of Sumatra, Indonesia. It was first scientifically described in 1878 by Italian botanist Odoardo Beccari. The plant flowers only infrequently in the wild and even more rarely when cultivated. It first flowered in cultivation at the Royal Botanic Gardens, Kew, London, UK in 1889, with over one hundred cultivated blossoms since then. The first documented flowerings in the United States were at the New York Botanical Garden in 1937 and 1939. This flowering also inspired the designation of the titan arum as the official flower of the Bronx in 1939, only to be replaced in 2000 by the day lily. The number of cultivated plants has increased in recent years, and it is not uncommon for there to be five or more flowering events in gardens around the world in a single year. Advanced pollination techniques mean that this plant is rarely cultivated by amateur gardeners. However In 2011, Roseville High School (Roseville, California) became the first high school in the world to successfully bring a titan arum to bloom.[10][11]

The pollen area as seen from the inside (UC Davis, California)

In 2003, the tallest bloom in cultivation, some 2.74 m (9 ft 0 in) high, was achieved at the Botanical Garden of the University of Bonn in Germany. The event was acknowledged by Guinness World Records.[12] On 20 October 2005, this record was broken at the botanical and zoological garden Wilhelma in Stuttgart, Germany; the bloom reached a height of 2.94 m (9 ft 8 in). The record was broken again by Louis Ricciardiello, whose specimen measured 3.1 m (10 ft 2 in) tall on 18 June 2010, when it was on display at Winnipesaukee Orchids in Gilford, New Hampshire, US. This event, too, was acknowledged by Guinness World Records.[13][14]

See also List of publicised titan arum blooms in cultivation

Visitors photograph a blooming corpse flower on display at Phipps Conservatory in the United States in August 2013

In cultivation, the titan arum generally requires 7 to 10 years of vegetative growth before blooming for the first time. After its initial blooming, there can be considerable variation in blooming frequency. Some plants may not bloom again for another 7 to 10 years while others may bloom every two to three years. A plant has been flowering every second year (2014,16, 18 and 2020) in the Botanical Garden in Copenhagen. [15] There have also been documented cases of back-to-back blooms occurring within a year[16] and corms simultaneously sending up both a leaf (or two) and an inflorescence.[17] There has also been an occasion when a corm produced multiple simultaneous blooms.[18]

The spathe generally begins to open between mid-afternoon[19] and late evening and remains open all night. At this time, the female flowers are receptive to pollination. Although most spathes begin to wilt within twelve hours, some have been known to remain open for 24 to 48 hours. As the spathe wilts, the female flowers lose receptivity to pollination.

Self-pollination is normally considered impossible, but in 1999, Huntington Botanical Garden botanists hand-pollinated their plant with its own pollen from ground-up male flowers. The procedure was successful, resulting in fruit and ten fertile seeds from which several seedlings eventually were produced.[20] Additionally, a titan arum at Gustavus Adolphus College, in Minnesota, unexpectedly produced viable seed through self-pollination in 2011.[21]

• Images of Amorphophallus titanum
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  Plant finishing blooming, showing the male and female flowers at the base of the spadix
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  First of two plants, Kew Gardens, London, May 1, 2009
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  Second of two plants, Kew Gardens, London, May 1, 2009
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  "Morticia", Franklin Park Zoo, Boston, Massachusetts, USA, June 20, 2012
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  Titan Arum, Royal Botanic Gardens, Melbourne, Victoria, Australia, December 27, 2012
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  "Morty", Buffalo and Erie County Botanical Gardens, Buffalo, NY, USA, August 8, 2014
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  Huntington Library, San Marino, California August 24, 2014
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  A. titanum close up, Bayreuth University, Germany, June 7, 2015
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  A. titanum close up, Bayreuth University, Germany, June 6, 2015
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  A. titanum, Bayreuth University, Germany, June 7, 2015
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  A. titanum close up, Bayreuth University, Germany, June 6, 2015
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  "Putrella", Muttart Conservatory, Edmonton, Canada, April 7, 2015
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  A. titanum leaflets, Muttart Conservatory, Edmonton, Canada
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  A. titanum with fruits, Liberec, Czech Republic

• Bown, Deni (2000). Aroids: Plants of the Arum Family. Timber Press. ISBN 0-88192-485-7
• Association of Education and Research Greenhouse Newsletter, volume 15 number 1.

Wikimedia Commons has media related to Amorphophallus titanum.

• Three Webcams of Titan plus time-lapse videos at Gustavus Adolphus College in Saint Peter, Minnesota
• 3D Photo of 2004 bloom at Walt Disney World (Requires red/cyan 3D Glasses)
• List of bloomings in the US since 1937
• How to grow a Titan Arum
• Titan Arum at the Flower Park Kagoshima of Kagoshima Prefecture, Japan (in Japanese)
• Amorphophallus titanum YouTube video