I would add that there isn't a person who decides if you get an acorn. Dave's software does the deciding. You can get one acorn for the first photo added to any category for the plant. By category I mean the form that comes up when you first submit a photo (entire plant, leaves, seeds, bulb, bloom are categories). You get an acorn for the first photo you submit in a category but not for additional photos for that category. So if you submit say three photos that you designate as "Bloom" you get just one acorn. The idea is to encourage folks to take photos of different parts of the plant.
Scroll to the bottom of the page and click on "Acorns" for the rules.