Picture Post is a phenological project created by the University of New Hampshire, that is now being run by the University of Oklahoma.
The project seeks to gather images of various locations around the globe. These images are classified and used to track plant life cycles and calibrate satellite readings used in research.
Using this app, you can take and upload photos, manage your posts, and check out other posts.
You can learn more about the project on the website:
https://picturepost.ou.edu/