LOL, I haven't heard anything stating that we shouldn't upload pictures when a flash was used and I've taken many a plant/flower photo using the flash, especially plants that bloom at night, light night blooming cactus. I used to go out on my screened porch at night to take flower photos using the flash. I agree with Jay, if the photo is a good representation of the plant in question you shouldn't hesitate to add it to the database.
