Green apples are often assumed to be a distinct species or simply unripe fruit, but this perception is inaccurate. The green apple available for purchase is a product of human intervention and selective breeding. All modern apple varieties, whether red, yellow, or green, are cultivars—plants selected and propagated for desirable traits. The green color and tart flavor of a popular variety like the Granny Smith did not occur naturally, but arose through an accidental genetic mutation that was intentionally preserved.
The Specific History of the Granny Smith Apple
The origin of the world’s most recognized green apple, the Granny Smith, is traced back to a single moment of chance discovery. This cultivar was first propagated in 1868 by Maria Ann Smith, an orchardist in Eastwood, a suburb of Sydney, Australia. Smith, who was locally known as “Granny Smith,” often experimented with seedlings on her property.
The original tree grew from a chance seedling near a creek where Smith had dumped the decaying remains of French crab apples. This accidental hybridization between a common apple and a wild crabapple resulted in a unique fruit with a distinctively tart flavor and vibrant green skin. Smith recognized the potential of this new apple, noting its firm flesh and good keeping qualities.
After her death, local orchardists continued to cultivate the variety using cuttings from the original tree. It was officially exhibited as “Smith’s Seedling” in 1890 and later marketed under her nickname, solidifying its place in horticultural history. Every Granny Smith apple tree in the world is a genetic clone of that single, original chance seedling.
Cultivation and the Domestication of Apples
The Granny Smith exemplifies the process defining all modern apples, which are fundamentally different from their wild ancestors. Apples are genetically characterized as “extreme heterozygotes,” meaning planting a seed will not produce a tree identical to the parent fruit. The resulting tree will be a unique hybrid with unpredictable characteristics, often yielding small, unpalatable fruit.
To ensure a specific variety, or cultivar, maintains its exact traits, commercial growers rely on grafting. Grafting involves taking a small cutting, known as a scion, from the desired apple tree and fusing it onto the rootstock of another tree. This process creates a genetic clone of the parent fruit, allowing for the reliable reproduction of its flavor, color, and texture.
Reliance on grafting rather than growing from seed is why all commercial apples are considered domesticated. The initial domestication of the apple (Malus domestica) began thousands of years ago in the Tian Shan mountains of Central Asia from its wild ancestor, Malus sieversii. Through centuries of human selection for size, sweetness, and storage life, the modern apple became an entirely cultivated product.
The Science Behind the Green Color
The color of an apple is determined by the concentration and balance of three primary pigments: chlorophyll, carotenoids, and anthocyanins. Chlorophyll is the pigment responsible for the green color, and it is present in the skin of all apples when they are immature. In most apples, chlorophyll naturally breaks down during ripening, allowing other pigments to become visible.
In green apple varieties, such as the Granny Smith, a genetic characteristic causes the chlorophyll to remain stable and dominant even when the fruit is fully mature. This stability prevents the underlying yellow carotenoid pigments from being expressed. Green apples also produce very low levels of anthocyanins, the compounds that create red, purple, and blue hues.
Anthocyanin production is often stimulated by exposure to sunlight and cool temperatures, which is why red apples develop a deeper color in the fall. The genetic makeup of green apple cultivars suppresses this pathway, keeping the fruit green regardless of sun exposure. The result is an apple that is ripe for harvest, yet retains the high chlorophyll content that gives it its signature bright green appearance.