and if you see something like: (random, arbitrary example off the top of my head)
Nepenthes alata (Hort ex. Veitch)
That means that Hort named the species, but may have placed it in the wrong category or given it an improper name, and Veitch fixed it. Or maybe its the other way around? haha. You won't encounter that unless you are reading some (probably) technical botanical texts like species descriptions and whatnot.
The reason the binomial is so great, is that, if you refer to a species just as "sibuyanensis", it could be a Nepenthes, or a bush, or a tree, or a mammal, or a frog, or a...
Which is why the genus is always attached, so you know the exact subject of conversation