The Power of Movement in Plants

This was Charles Darwin's final scientific work, completed when he was 71 years old and in failing health. The book documented his elegant experiment with grass seedlings and opaque caps, demonstrating that plants sense light direction and transmit signals from tip to stem.

Darwin's observation that 'some influence is transmitted from the upper to the lower part, causing the latter to bend' laid the foundation for 150 years of plant hormone research. He died two years later without knowing the 'influence' was auxin, but his experimental design and core insight remain foundational to understanding how organisms detect and grow toward resources.