Plant Ontology (PO)

Plant Ontology (PO)


The main objective of the Plant Ontology Consortium (POC) is to develop, curate and share controlled vocabularies (ontologies) that describe plant structures and growth and developmental stages, providing a semantic framework for meaningful cross-species queries across databases. The Plant Ontology (PO) has been developed and maintained with the primary goal to facilitate and accommodate functional annotation efforts in plant databases and by the plant research community at large. As a part of the POC project, participating databases such as TAIR, NASC, Gramene and MaizeGDB have been using PO to describe expression patterns of genes and phenotypes of mutants and natural variants. The Plant Ontology Consortium (POC) is funded by the National Science Foundation.

Plant Structure

A controlled vocabulary of botanical terms describing morphological and anatomical structures representing organ, tissue and cell types and their relationships. Examples are gametophyte, parenchyma, guard cell, etc.


Growth and developmental stages

A controlled vocabulary of terms describing (i) whole plant growth stages and (ii) plant structure developmental stages. Examples are seedling growth, rosette growth, leaf development stages, embryo development stages, flower development stages, etc.


Plant ontology is not an extensive collection of botanical terms, but rather a complex hierarchical structure in which botanical concepts are described by their meaning and by relationship to each other. The main purpose of these vocabularies is to facilitate cross database querying and to foster consistent use of these vocabularies in the annotation of tissue and/or growth stage specific expression of genes, proteins and phenotypes. Educational aspect of the plant ontology is to some extent limited; this is imposed by the structure of the ontology itself and the limitations of the current software.