On the big photo stock pages you get a very small commission on your own photos and you might very well drown in a huge ocean of choices. Having your own photo stock site would require you to promote your stock photo yourself, but you would also be able to charge more, or even quite a bit more!
The owner of Rareplants.eu sell a very large variety of plant seeds, that can be browsed by Family or Genus, but he also run his own stock photo website on plants - Pixelflora.eu His pictures are really pretty good I must say!
Maybe this is what you should look into if you have - or will have - a good stock photo portfolio? I certainly hope to do something similar some day when I move back to the tropics!