Plant Gender
Over the course of three years, from 1691 to 1694, German botanist and physician Rudolf Jakob Camerarius discovered that plants, or plant parts, can be either male or female. When he removed the male flowers on one plant, the plant produced no seeds. He then fertilized another plant using pollen from the removed flowers, and the second plant produced seeds. Therefore, he learned, the stamens could be considered the male sexual organs and the pistil the female sexual organs of the plant. At the time, this was one of the most profound observations made in the field of botany.
Taxonomy
Augustin Pyrame de Candolle, a Swiss botanist, developed a standard plant classification system in 1813. His system used plant anatomy rather than plant physiology. Therefore, he developed the structural criteria needed to separate plants into different genera and species. The first explanation of this classification system, considered to be the start of plant taxonomy, was published in Candolle's book "Theorie elementaire de la botanique."
Cell Nucleus
Scottish botanist Robert Brown discovered the nucleus of the cell in the 1830s when observing orchids under a microscope. He determined there was only one nucleus in each cell and, while it was not fixed in a specific location, it tended to be in the center of the cell. Once he discovered the nucleus in the orchid cells, he also found it in many other monocotyledonous plants and even in some dicotyledonous plants. His discovery was published in "The Miscellaneous Botanical Works of Robert Brown" in 1866.
Photosynthesis
The discovery of photosynthesis occurred in 1779 by a Dutch physician, Jan Ingenhousz, who took a leave of absence from his physician job and conducted a series of experiments on plants when he was in England. He placed plants in clear containers and then submerged them. He saw that the undersides of the leaves produced bubbles when the plants were receiving sunlight. He eventually discovered that this gas was oxygen, although the entire mechanism of photosynthesis was not discovered until much later.