ABSTRACT. The paper addresses the problem of automatic generation of natural language descriptions for ontology- described artifacts. The motivation for the work is the challenge of providing textual descriptions of auto- matically generated scientific workflows (e.g., paragraphs that scientists can include in their publications). The paper presents two systems which generate descriptions of sets of atoms derived from a collection of ontologies. The first system, called nlgPhylogeny, demonstrates the feasibility of the task in the Phylotastic project, that aims at providing evolutionary biologists with a platform for automatic generation of phylogenetic trees given some suitable inputs. nlgPhylogeny utilizes the fact that the Grammatical Framework (GF) is suitable for the natural language generation (NLG) task; the paper shows how elements of the ontologies in Phylotastic, such as web services, inputs and outputs of web services, can be encoded in GF for the NLG task. The second system, called nlgOntology^A, is a generalization of nlgPhylogeny. It eliminates the requirement that a GF needs to be defined and proposes to use annotated ontologies for NLG. Given a set of annotated ontologies, nlgOntology^A will generate a GF suitable for the generation of natural language description of a set of atoms derived from these ontologies. The paper presents the algorithms used in the development of nlgPhylogeny and nlgOntologyA and discusses potential uses of these systems.