Use specific nutrients as keywords, such as nitrogen, phosphorus, potassium, if necessary. Often, the categories of reproduction, flowering and germination are used as well. Further refinements to the search can be made by using keywords such as phytochemistry, crassulacean acid metabolism, gas flow or gas transport, rubisco, etc. An ecosystem level of research can also be found using physiology as a category especially if primary production and photosynthesis are both investigated, or if nutrient cycling is the focus of research. Very often, surveys are involved and the keywords phytosociology, species composition, associations, communities, competition and populations will locate this kind of research.
Pollution control is used to indicate a method of controlling pollution with plants.
Wastewater and pollution control brings up sites about using plants for sewage treatment. If a new technique or equipment is involved, then method is used as a keyword. Reproduction used in conjunction with ontogeny can be used to identify research at the micro level, especially when keywords such as sporogenesis, embryogenesis, etc. are added. Yet another use of reproduction is to locate articles on micropropagation or tissue culture . If the research is describing a new procedure, then the word method can be added in the list of search keywords.