An aerobic gram-positive organism that develops aerial and vegetative branched filaments. The colonies are small, leathery, gray to white and have a granular, powdery or velvety appearance due to the aerial mycelium present. Some strains produce a deep blue diffusible pigment in the medium. Colonies produce an earthy odor. It has been isolated from soil, plants, dust, water, compost, and manure. It causes human infections following .inhalation, or by contamination of an area of trauma.