Another good location for lilac photos is at any local library. Many plant books will have images of the plants and shrubs discussed, and lilacs are generally included. Gardening and agriculture periodicals at a library may also contain pictures of lilacs. There may even be books that emphasize only lilacs, and these would no doubt include pictures of lilacs and their brightly colored blooms and foliage.
Nurseries and garden centers are also a good source of lilac photos. Along with pictures of lilacs, these places will also likely have live specimens of several varieties of lilac. They will also generally have catalogs or books that will contain lilac pictures.
As lilac plants come in several different varieties, any online retailer or wholesale distribution center is sure to have pictures of lilacs, and the other flowers that they offer for sale. This will no doubt make it easier for the customers to decide which plants they would like to buy. As lilac pictures greatly enhance the sale, any mail-order company will also have pictures in the catalogs that they provide.