The world’s largest plant is a single organism of Posidonia oceanica, a species of seagrass found in the Mediterranean Sea. This particular Posidonia oceanica is a vast clonal colony that covers an area of around 180,000 square meters (about 45 acres) and is located off the coast of the Spanish island of Ibiza.

Key Features of the Largest Plant:

1. Clonal Growth: The plant is not a single individual organism in the traditional sense but rather a large clonal colony. Posidonia oceanica spreads through horizontal growth of its roots (rhizomes), allowing it to cover an extensive area. The colony is genetically identical, with each shoot coming from the same original plant.
2. Age and Size: This Posidonia oceanica colony is believed to be around 100,000 years old, making it not only the largest but also one of the oldest living organisms on Earth. It grows very slowly, adding just a few centimeters per year, which is why its size is so impressive.
3. Ecological Importance: As a seagrass, Posidonia oceanica plays a vital role in the ecosystem. It provides habitats for a wide variety of marine species, helps stabilize the sea floor, and improves water quality by trapping sediments and producing oxygen.

While Posidonia oceanica holds the record for the largest plant, in terms of individual size, the giant sequoia trees (Sequoiadendron giganteum) in California are often considered the largest trees and living organisms by volume. The largest known giant sequoia, named General Sherman, stands about 275 feet (83 meters) tall and has a volume of around 52,500 cubic feet (1,487 cubic meters), though this tree is still not larger in terms of land area than the seaweed colony.

So, while Posidonia oceanica holds the title for the largest plant in terms of area covered, the giant sequoia holds records in terms of volume and height.