Leafsnap: Mobile applications for plant identification for ecologists and citizen scientists using image recognition technology

Background/Question/Methods

Both ecologists and citizen scientists need fast, reliable, and easy-to-use field guides for plant identification.  Traditional paper-based guides or more recently introduced electronic field guides essentially use the same methodology, which is based on following dichotomous keys or selecting specific information on morphological features of the focal plant. With these types of identification aids a certain level of botanical skill is often required and in many cases a specific feature needed to make a correct identification (i.e., flower, fruit) is unavailable.  We have developed a new automated identification tool that makes use of computerized image recognition technology.  The tool, called Leafsnap, employs an algorithm that establishes the contours of the leaf of an unidentified tree and uses uniquely developed visual recognition software to find a match from a previously constructed digital library of leaf images.

Results/Conclusions

This free mobile app, currently available for the iPhone and iPad, identifies trees from photographs of their leaves and contains high-resolution images of their flowers, fruits, seeds, and bark. After taking a photo of a leaf of the plant to be identified, the iPhone will compare the photograph to a central library of 8000 images that have been collected and stored in the home database server. A ranked list of possible species is returned to the user at which time Leafsnap displays high-resolution images of a branch, leaf, flower, fruit, and bark of the identified species. The app also supplies descriptive information as well as native distribution. Leafsnap returns search results in 5 to 20 seconds, depending on the speed of the network connection. Ultimately it is up to the user to make the correct determination by using the high-resolution images in the database to compare critical diagnostic features with the species under question. Once an identification is made, the image is automatically sent to Leafsnap's home database along with mapping information taken from the smart phone's GPS.  This information will eventually be used to track the geographic ranges of trees as they change over time.  Currently the app is specific to about 200 tree species of the northeastern United States.  It is planned that within two to three years Leafsnap will cover all the trees of North America, nearly 800 species in total.