Please refer to "An Introduction to Plant Taxonomy - Page 92 - Google Books" for detail explanation, and a very good example. [ https://books.google.com/books?id=vqw8AAAAIAAJ&pg=PA92&lpg=PA92&dq=synonym+and+homonym+in+plants&source=bl&ots=QzUXHxBe7y&sig=ieI80bEXLd_aK79i72R6f0LNP8g&hl=en&sa=X&ei=wKfZVN6jIomMNpvKgcAL&ved=0CEwQ6AEwBw#v=onepage&q=synonym%20and%20homonym%20in%20plants&f=false ]