A bud sport is a part of a plant or tree — for example, a leaf, shoot or flower — which due to a genetic mutation clearly differs from the rest of the plant, and which can also be grafted to grow new plants which retain this genetic difference.

When bud sports are discovered on fruit trees, they are sometimes used as a new variety, for example, a nectarine is a bud sport of the peach.

Bud sports can also happen to garden plants, where for example a pink flower can appear on a genetically white-flowered plant.