− | 1. Leafsnap is an on-line field guide, available as a free mobile app that uses visual recognition software to help identify tree species from photos of their leaves, flowers and fruits <ref>Columbia University, University of Maryland, Smithsonian Institute. 2018. Leafsnap. http://leafsnap.com/species/</ref> | + | 1. Leafsnap is an on-line field guide, available as a free mobile app that uses visual recognition software to help identify tree species from photos of their leaves, flowers and fruits. <ref>Columbia University, University of Maryland, Smithsonian Institute. 2018. Leafsnap. http://leafsnap.com/species/</ref> |