Plant research has often been done with plants. In genetics, the breeding of pea plants allowed Gregor Mendel to derive the basic laws governing inheritance, and examination of chromosomes in maize allowed Barbara McClintock to demonstrate their connection to inherited traits. The plant "Arabidopsis thaliana" is used in laboratories as a model organism to understand how genes control the growth and development of plant structures. NASA predicts that space stations or space colonies will one day rely on plants for life support. Ancient trees are revered and many are famous. Tree rings themselves are an important method of dating in archeology,
Plant breeding agricultural plants, a practice which is estimated to date back 9,000 to 11,000 years. Initially early farmers simply selected food plants with particular desirable characteristics, and employed these as progenitors for subsequent generations, resulting in an accumulation of valuable traits over time. Grafting technology had been practiced in China before 2000 BCE. By 500 BCE grafting was well established and practiced. Gregor Mendel (1822–84) is considered the "father of modern genetics". His experiments with plant hybridization led to his establishing laws of inheritance. Genetics stimulated research to improve crop production through plant breeding. Modern plant breeding is applied genetics, but