Available space theory

{{Short description|Theory explaining plant leaf patterns}}

In botany, available space theory (also known as first available space theory) is a theory used to explain why most plants have an alternating leaf pattern on their stems. The theory states that the location of a new leaf on a stem is determined by the physical space between existing leaves. In other words, the location of a new leaf on a growing stem is directly related to the amount of space between the previous two leaves.{{cite web| title=Available space theory| publisher=Dictionary of Botany| accessdate=2012-05-24| url=http://botanydictionary.org/available-space-theory.html}} Building on ideas first put forth by Wilhelm Hofmeister in 1868, Snow and Snow hypothesized in 1947 that leaves sprouted in the first available space on the stem.{{cite book| title=Meristems, Growth, and Development in Woody Plants: An Analytical Review of Anatomical, Physiological, and Morphogenic Aspects| last=Romberger| first=John| publisher=U.S. Government Printing Office| year=1963| page=37}}