What concept did Matthias Schleiden contribute to the understanding of biology?

Matthias Schleiden is known for his pivotal contribution to the cell theory, particularly regarding plants. He proposed that all plant tissues are composed of cells, which was a significant realization in the understanding of biology. This idea was crucial because it emphasized that cells are the fundamental units of life in all living organisms, not just animals. By recognizing that plants are made up of cells, Schleiden helped to unify the study of biology under the concept that cells are the basic building blocks of both plant and animal life, laying the groundwork for future biological research and understanding of living systems. This concept formed the basis for the later developments in cell theory, alongside the contributions of other scientists like Theodor Schwann, who applied similar ideas to animals.