The term clone is used in horticulture to refer to descendants of a single plant which were produced by vegetative reproduction or apomixis. Many horticultural plant cultivars are clones, having been derived from a single individual, multiplied by some process other than sexual reproduction. As an example, some European cultivars of grapes represent clones that have been propagated for over two millennia. Other examples are potato and banana.
Grafting can be regarded as cloning, since all the shoots and branches coming from the graft are genetically a clone of a single individual, but this particular kind of cloning has not come under ethical scrutiny and is generally treated as an entirely different kind of operation.
Many trees, shrubs, vines, ferns and other herbaceous perennials form clonal colonies naturally. Parts of an individual plant may become detached by fragmentation and grow on to become separate clonal individuals. A common example is in the vegetative reproduction of moss and liverwort gametophyte clones by means of gemmae. Some vascular plants e.g. dandelion and certain viviparous grasses also form seeds asexually, termed apomixis, resulting in clonal populations of genetically identical individuals.
Cloning trees is fundamentally different from cloning animals, bypassing high-tech laboratory embryo manipulation to rely on the natural, built-in capacity of plant cells to regenerate entire organisms from a single piece of tissue. While nature has used tree cloning for millions of years to preserve massive forest networks, modern arborists use advanced micropropagation to preserve ancient genetics and fight climate change.
Nature's Built-In Clones
Long before human science, some of the planet's largest organisms survived entirely through natural cloning:
The Pando Aspen Grove: Located in Utah, Pando is a massive forest of 47,000 quaking aspen trees spanning over 100 acres. DNA testing proved that every single tree is a "ramet" - an identical genetic clone sharing a massive, single underground root system estimated to be up to 14,000 years old.
Redwood Fairy Rings: Coastal redwoods possess specialized, bulbous tissue called "burls". When a parent redwood is stressed, burned, or logged, the dormant buds within the burl send out sprouts. These sprouts grow into a perfect circle of identical clone trees - often referred to as a cathedral ring surrounding the original stump.
Scientific Methods of Tree Cloning
Arborists and industrial foresters rely on three primary artificial cloning methods, ranging from basic backyard techniques to advanced sterile laboratories:
1. Air Layering: This manual method involves scraping away the outer bark of a living branch to expose its inner cambium cells. Propagators wrap the wound in moist sphagnum moss and plastic. Once roots form directly on the branch, it is sawed off and planted as a freestanding clone.
2. Grafting: To clone delicate or stubborn species, scientists cut a young branch (a scion) from a target tree and physically fuse it onto the rooted stem of a hardy seedling. The cambium layers grow together, creating a tree with a generic root system but the exact crown genetics of the parent.
3. Somatic Embryogenesis: In high-tech forestry labs, scientists take a single seed embryo or tissue sample and place it in a petri dish filled with custom plant-growth hormones. The treatments force the cells to continuously multiply into thousands of identical embryos, allowing a single seed to mass-produce millions of identical trees.
Cloning the "Monarchs" to Fight Climate Change
One of the most ambitious applications of tree cloning is spearheaded by nonprofits like the Archangel Ancient Tree Archive.
The Mission: Arborists scale massive heights or locate the living tissue on centuries-old stumps of ancient coast redwoods and giant sequoias that were logged in the 19th and 20th centuries.
The Carbon Weapon: Old-growth redwoods sequester up to 250 tons of carbon dioxide over their lifespans compared to just 1 ton for a standard tree. By cloning the exact genetic survivors that withstood thousands of years of pests, droughts, and fires, scientists are planting "supergroves" designed to maximize global carbon capture.
The Ecological Risk
Despite the benefits, relying too heavily on cloned trees introduces a major vulnerability: monoculture. In a natural forest, genetic diversity ensures that if a new disease or pest arrives, some trees will have a random genetic immunity to survive. If an entire commercial timber forest or urban park consists of the exact same tree clone, a single pathogen could instantly wipe out every single tree simultaneously.
California: World's oldest tree cutting collected for cloning
October 2002 - CNN
A nonprofit group has snipped some cuttings to clone what is believed to be the world's oldest tree, a bristlecone pine they say has grown for 4,767 years on a wind-swept mountain in eastern California. With the guidance of a U.S. Forest Service ranger, representatives from Michigan-based Champion Tree Project International hiked Tuesday to the tree, at an elevation of 10,400 feet in the White Mountains on the California-Nevada border. The tree was dubbed Methuselah after scientist Edmund Schulman found it and age-dated it by a core sample in the 1950s. Although the name is biblical, the tree is believed to predate Christ by almost 3,000 years. "It's healthy," said David Milarch, co-founder with his son of the tree project. "It's gnarly from almost 5,000 years of harsh weather. But they got plenty of good material."
The specimens to Chris Friel, a doctoral student in plant pathology at UC Davis who is trying to clone the tree. "Within a year, either I'll have an itty bitty little tree or I won't," Friel said. "Frankly, the chances on an ancient tree are extremely slim." David Milarch said the Methuselah tree stands about 55 feet tall, with a misshapen oval-shaped trunk measuring about 41/2 feet wide.
Jared Milarch and Mock also took samples for cloning from a bristlecone pine believed to be the largest of the species and growing in the same forest -- a 60-foot tall tree known as "the Patriarch." Richard Harris, a forestry specialist at the University of California, Berkeley, said it was possible that the Methuselah tree was the oldest in the world. However, he said boring provides only an age estimate, and noted the difficulty of accurately counting 4,767 rings in a core sample from a twisted bristlecone trunk just 41/2 feet across.
The Forest Service backed the Champion Tree Project's efforts to clone prized trees for research and to restock sparse forest areas, Payne said. The nonprofit National Tree Trust also helped the effort. The Milarches began the Champion Tree Project in 1996, and have attempted to clone more than 70 trees nationwide. The organization provided a clone from a 450-year-old champion red ash for planting at a September 11 Pentagon memorial. It also collected bits of poplar trees said to have been planted by George Washington on his estate, Mount Vernon, and expect to return clones for replanting. "We're finding the last genetic links to forests that were here for tens of thousands of years," David Milarch said.