Botanical illustration is the art of depicting the form, color, and details of plant species. They are generally meant to be scientifically descriptive about subjects depicted and are often found printed alongside a botanical description in books, magazines, and other media. Some are sold as artworks. Often composed by a botanical illustrator in consultation with a scientific author, their creation requires an understanding of plant morphology and access to specimens and references.

Many illustrations are in watercolour, but may also be in oils, ink, or pencil, or a combination of these and other media. The image may be life-size or not, though at times a scale is shown, and may show the life cycle and/or habitat of the plant and its neighbors, the upper and reverse sides of leaves, and details of flowers, bud, seed and root system.

Botanical illustration is sometimes used as a type for attribution of a botanical name to a taxon. The fragility of dried or otherwise preserved specimens, or restrictions on transport, have made illustrations viable alternative visual references for taxonomists. Many minute plants or botanic specimens, which may only be visible under a microscope, are often identified by an illustration to overcome the difficulties in submitting slide-mounted type specimens. The standards for this are by international agreement (Art 37.5 of the Vienna Code, 2006).