The Plant Ontology is a controlled vocabulary (ontology) that describes plant anatomy and morphology and stages of development for all plants. The goal of the PO is to establish a semantic framework for meaningful cross-species queries across gene expression and phenotype data sets from plant genomics and genetics experiments.
Beginning in January 2011 (Version #14), the Plant Ontology was merged into a single ontology file (from two separate files) encompassing the following two aspects:
Botanical terms describing plant structures and other anatomical entities and the relationships between them.
Examples of plant anatomical entities are plant structures (PO:0009011) such as plant organ (PO:0009008), plant cell (PO:0009002), whole plant (PO:0000003), portion of plant tissue (PO:0009007), and vascular system (PO:0000034), etc.
A controlled vocabulary of terms describing the stages of plant structure development.
Example of plant structure development stages are: plant tissue development stage (PO:0025423), leaf development stage (PO:0001050), whole plant development stage (PO:0007033), seed development stage (PO:0001170), and sporophyte development stage (PO:0028002), etc.