Most magazines require a writer to provide images. That means taking photographs. Depending on how they turn out, you might have to change your writing.
Lets say you wanted to write about rhododendrons, azaleas, and camellias. Problem is, when you got to the arboretum the camellias were bloomed out. But perhaps a Redbud was in full bloom. You better take its picture and get ready to write about Redbuds. Or omit any mention of camellias.
While finding images on the web is easy, don’t count on a Google search to save your article. You’ll need a high resolution image, something around 300 dpi, which ordinarily isn’t available unless you subscribe to a stock image service. Make sure you can use it in a for-profit magazine in case your editor asks.
With someone else’s image you’ll need a release unless there is language with the photo to indicate otherwise. Wikipedia and some other services release photos if proper credit is given.
A complicating factor is that you don’t often know which photograph an editor may use. You may slave to find that camellia photo only to learn the editor and layout person decided against it.
I am currently submitting an article to a magazine. They want 12 to 15 photos to accompany it. Three or four photos might eventually be used. On a field trip I’ll take 25 to 50 photographs, some with my iPhone and some with my Sony point and shoot camera. I’ve even take photographs with the camera built into my GPS unit.
Between all three cameras I stand a good chance of of producing something useful. But I am always prepared to rewrite, especially if a great photograph gives me the chance to write about something I hadn’t originally planned.