Rafflesia, the plant that has always been entertaining and astounding the world with its world’s largest flower, is found to have evolved from a plant-family whose blossoms are nearly all tiny.
Rafflesia – with a flower typically a full meter across, with a bud the size of a basketball — is closely related to a family that includes poinsettias. Poinsettias are the trees that produce natural rubber, castor oil plants, and the tropical root crop cassava. Botanists have discovered this from the genetic analysis of the plant.
Confounding plant scientists for nearly 200 years, the rafflesia blooms over an estimated 46 million years, now weighing up to 15 lbs! It is found to have evolved at an accelerated pace. As being published this week in the journal Science, the rafflesia has increased in size by a factor of roughly 79. The plant then reverted to a more sedate evolutionary pace.
Harvard’s Charles C. Davis, an assistant professor of organismic and evolutionary biology in Harvard’s Faculty of Arts and Sciences said,
For nearly 200 years rafflesia’s lineage has confounded plant scientists. As a parasite living inside the tissue of a tropical vine, the plant lacks leaves, shoots, or roots, making it difficult to compare to more conventional plants.
Most efforts to place plants in the botanical tree of life in the past 25 years have tracked ancestry using molecular markers in genes governing photosynthesis. Rafflesia is a non-photosynthetic parasite, and those genes have apparently been abandoned, meaning that to determine its lineage we had to look at other parts of the plant’s genome.
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Photo Credit: Jeremy Holden, July 2005