Plant bodies are composed of organs having distinct positions on the plant body, morphological and anatomical characters, and functions. Roots obtain water and nutrients form soil, leaves assimilate carbon using the energy of the sun, and stems connect roots and leaves. Except for those basic organs and their basic functions, plant bodies need to fulfill other functions that are then provided by specialized organs (composed from these basic organs). For example, for resprouting after disturbance, plants employ organs called lignotubers composed from stems and roots deposited belowground that store carbohydrates and the bud bank. In ecology we are using traits of the organs as easy surrogates for complicated functions when comparing strategies across plant species. For example, thinner leaves are more effective in photosynthesis, so by using this measure, we can order plants according to their leaf economic spectrum from acquisitive (thin leaves) to conservative (thick leaves). The function of plant organs approximated by functional traits is tested and used in so called trait-based ecology.