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Question What is the largest flower in the world?

Answer

The Rafflesia arnoldii.

Rafflesia arnoldii (corpse flower) growing to the east of the Lake Maninjau, Sumatra, Indonesia. Henrik Hansson. External link Plants of the World Online, Kewscience.

The flower with the world’s largest bloom is the Rafflesia arnoldii. This rare flower is found in the rainforests of Indonesia. It can grow to be 3 feet across and weigh up to 15 pounds! It is a parasitic plant, with no visible leaves, roots, or stem. It attaches itself to a host plant to obtain water and nutrients.

Rafflesia arnoldii (corpse flower). From An account of a new genus of plants, named Rafflesia. London: Printed by Richard and Arthur Taylor, 1821. External link Biodiversity Heritage Library.

When in bloom, the Rafflesia emits a repulsive odor, similar to that of rotting meat. This odor attracts insects that pollinate the plant.

Titan arum close-up. Architect of the Capitol Flickr Photostream

Another enormous flower found in Indonesia is the Amorphophallus titanum, or Titan arum. It is also known as the “corpse flower” for its unpleasant odor. Like the Rafflesia, the Titan emits the smell of rotting flesh to attract pollinators. Technically, the Titan arum is not a single flower. It is a cluster of many tiny flowers, called an inflorescence. The Titan arum has the largest unbranched inflorescence of all flowering plants. The plant can reach heights of 7 to 12 feet and weigh as much as 170 pounds!

Three corpse flowers bloomed at USBG in 2017: Illustration by Chicago Botanic Garden. United States Botanic Garden (USBG). 

Published: 11/19/2019. Author: Science Reference Section, Library of Congress

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