It's Olly who gave the most complete answer for your taxonomical needs. You miss the links that are not like:
http:// etc.and all what it may contain.
(1)The most common of common names for plants are the ones you hear in your area/neighborhood/town. They may differ a lot locally.
(2)Look at garden centre's labels or just work you way through WIKI plant world. For repens, replens, you need to replenish your Latin.