Pando: World’s most massive organism

Move over blue whales and mammoths! Plants rule the world, and they also bag the coveted title of the world’s most massive organism on the planet. Would you believe the grove of aspen trees shown above is actually one organism? It’s called the Pando, which is Latin for “I spread”. And that’s what the tree has been doing since the last ice age! It’s also nicknamed The Trembling Giant, after the trembling aspen (Populus tremuloides), a deciduous tree native to the cooler areas of North America, whose seeds seeded the Pando.

A very long time ago in the planet’s history (scientists are yet to give a number on how old Pando is, estimates vary from a million years to 80,000 years), a single seed of the trembling aspen began to grow in the Fishlake National Forest in Utah, USA. Its underground root system became massive and the plant started to reproduce through ‘suckering’—the expanding roots sent out erect stems that grew into individual trees above the ground but were connected to a single root system below. The plant continues to thus create clones that are genetically identical—a fact confirmed in recent years although scientists first observed this unique grove in the 1970s.

Today, the Pando has expanded to over 108 acres, or the size of 62 football fields, in its area. It weighs over 6,000 metric tonnes (a blue whale, for comparison, weighs only 200 metric tonnes on average!). The entire grove is estimated to have about 40,000 individual stems or trunks, each living for about 100-130 years before being replaced by newer stems for thousands of years.

In the last few decades, however, scientists say the Pando is dying, with fewer new stems replacing the older ones. It’s partly due to overgrazing on nearby ranches, and the wild mule deer, whose numbers have skyrocketed without apex predators like grizzly bears, wolves or mountain lions, that have been hunted to near-extinction. Insects like bark beetles, and diseases like root rot and cankers, are also slowly eating up the remaining stems. The lack of genetic diversity among the clones in the grove puts the Pando in a vulnerable spot.

- Spoorthy Raman