The Plant Environment Ontology describes the treatments,growing conditions, and/or study types used in various types of plant biology experiments. The subjects of the studies may also include in vitro plant structures (PO:0000004). A plant treatment is the most specific,and may be a component of a plant growing condition, and the plant study type. The broadest classes are the plant study types where the terms can be used to identify the growth study facility. Each growth facility such as field study, growth chamber, green house etc is a environment on its own and it may also involve instances of biotic and abiotic treatments and different growing conditions.