The painter Leonardo da Vinci (1452–1519) noticed this phenomenon. He also saw that the year’s dampness can be determined by the space between the tree’s rings. The farther apart the rings, the more moisture there was in the ground around the tree.

Many scientists believe land plants evolved from green algae. Green algae, especially the charaophytes, share a number of biochemical and metabolic traits with plants. Both contain the same photosynthetic pigments—carotenes, xanthophylls, as well as chlorophylls a and b. Cellulose is a major component of the cell walls of plants and algae, and both store their excess carbohydrates as starch. In addition, some aspects of cell division, particularly the formation of new cross-walls, only occurs in plants and certain charaophytes, such as species of the genera Cerara and Colechaete.