《植物变形记》是歌德写的一篇关于花叶变形的理论。歌德对植物学情有独钟，他认为动物和植物都存在一种"原形态"。动物的原形是脊椎骨，而植物的原形是叶子，动植物都是从各自的"原形"经过漫长的演变进化而来，这几乎就是进化论的观点。1790年歌德在《植物变形记》这篇论文中阐述了他的观点。他创造了"形态学"（morphology）一词，意为"对生物结构的系统研究"，该词一直沿用到现在。(The Metamorphosis of Plants introduces a theory written by Goethe about how leaves and flowers change forms. Goethe who had a particular liking for botany, held the belief that both animals and plants took shape in an original form, which were spines and leaves correspondingly, and evolved into their current forms after a long phase, which is almost Darwinism. In The Metamorphosis of Plants, a paper written by Goethe in 1790, he coined the word "morphology" meaning a systematic research on biological structure, which has been used so far. )