Why Are Bonsai Plants Small? A Consideration of Cell Size

Abstract

Size determinants of organisms are still a great puzzle. Analysis of dwarfs or giants within a certain taxon is a promising tool for a functional understanding of size control. Bonsai cultivation techniques lead to the most extreme forms of environmentally induced plant dwarfism. It is shown that no such changes take place at the level of cell size of leaves. Leaves of four out of six species of Bonsai had even bigger cells than leaves of normal trees, which is similar to what was observed in genetically dwarf plants from high altitudes. These results illustrate the insignificance of intraspecific cell size variations for explanations of differences of size and growth of plants. Genetic control of cell size is stronger than the most severe environmental impact as it is received by Bonsais. The relevance of concepts developed for the control of cell size and cell division in unicellular organisms for meristematic plants is discussed.