GrowApp helps you track and visualize changes in the appearance - the 'phenology' - of trees and other vegetation. The phenology of a particular tree at a certain location and a certain moment in time is stored in the GrowApp cloud-database by adding a photo taken with this app. The app presents a geographic map with the locations of all photos taken by all users. A photo can be viewed by tapping the corresponding photo location. If the photo location happens to be near your current location, you can add new photos of the same subject. The app then shows a semi-transparent version of the previous photo on top of the camera view so that camera and photo can be visually aligned. Once more than one photo of the same subject at the same location has been taken, the app automatically constructs time-lapsed versions of these photos. If enough photos are taken over sufficiently large intervals, the resulting animations should clearly show all aspects of the changing vegetation phenology over time.