Hi Reid, Here's a link to the Multi-Plant Photos home page. Just select "Add an image".
http://garden.org/apps/sets/
P.S. There's a few ways to get there.
Select "Goodies" in the left sidebar, then select "Multi-Plant Photos".
On the ATP home page scroll down to the "New Multi-Plant Photos" area and select "See more new multi-plant photos".
Open a "Multi-plant photo", under the photo select "Return to the Multi-Plant Photos homepage".