What is the largest organism on Earth?
An elementary student might respond with, “The blue whale.” Let us face it, most of us think about animals when it comes to biology.
Someone who has grown passed the childhood obsession with animals or expanded upon it might respond with, “The redwoods,” or “The sequoia.” I know growing up I read how the redwoods are the tallest trees but the sequoias are wider and heavier.
However, my natural history knowledge expanded greatly thanks to Dr. Stephenson, my favorite biology professor. He has traveled the world studying plants and fungi, and particularly appreciates Australia.
Why does that matter? Well, the southern hemisphere has a large, infamous genus of trees known as the eucalyptus. Of the 700 species in this genus several compete with the redwoods and sequoias.
Go to areas of southeastern Australia or 150 miles south of the mainland to Tasmania and you can find Eucalyptus regnans, the mountain ash. You will recognize it by its shaggy bark, sickle-shaped leafs and, well, height. Historically this is the tallest tree in the world. Many specimens has been measured beyond 400 ft tall. The tallest redwood, Hyperion, is 379 ft.
Unfortunately, Eucalyptus are ideal for logging, so the more typical height for this species is now 270 ft. So the redwood can rightfully claim the tallest tree right now.
But neither are the largest organism on earth.
It might be a plant that scientists do not always acknowledge as a single organism. Does it count?
A lot of plant and fungi produce or reproduce vegetatively. By that I ask, if a tree spurts an additional trunk from its roots, is that the same individual? They come from the same seed. The nutrients are absorbed and distributed between both. They are genetically identical. At this point, if the root systems are indeed still intact then the tree produced a second stem and if the root systems separate then the tree reproduced a clone.
Now here is the panda, as MinuteEarth’s Youtube video puts it. A seed from 80,000 or more years ago found itself on a plateau in Utah. It has expanded into a 106 acre forest. The 40,000 trunks might weigh upward of 13 million pounds.
This quaking aspen is called Pando, which is Latin for “I spread.” Although the most wide-spread of trees, it does not compete with a forest fungus in Oregon. That organism grows across 2400 acres.
Overall the fungus (Armillaria solidipes) is the heaviest organism. However, biologists like to measure by biomass, which is the weight of the organism without water. In this sense, Pando is bigger.
Pando also competes to be the oldest living organism.
Other competitors include other vegetatively producing organisms such as a jurupa oak potentially 30,000 years old; a creosete bush around 13,000 years; and a marine plant (Posidonia oceanica) in the Mediterranean for mayhap 80,000 years.
Much of this I learned in a university forest ecology class, so I very much appreciate going over the material in a 3 minute YouTube video a year later. While the Eucalyptus were very much ignored and thus partly responsible for my rant, the video easily explains and illustrates these natural phenomenons.