The Olive Trees series by Vincent van Gogh is a collection of paintings created during his time at the psychiatric hospital in Saint-Rémy-de-Provence in 1889. These paintings depict the twisted shapes of olive trees in a vivid and expressive manner, reflecting van Gogh's emotional state at the time. The trees are portrayed with exaggerated forms and vibrant colors, showcasing van Gogh's unique artistic style and his ability to convey his inner turmoil through his brushstrokes.