How do you define a species in botany?

Question

I know that in zoology, to be the same species, the two organisms must be able to reproduce and have fertile offspring.

What about in botany?

Answer 1

It's the same.  Zoology and botany are both subcategories of biology which is where the definition you have comes from.

Answer 2

It's the same, but frequently more complicated.  Many hybrid plants are fertile, meaning different species can interbreed freely.

Unfortunately, the word species is rather poorly defined.  In some cases, it just means they look different, in other cases, it means that different species can not interbreed and have fertile offspring (this is not always true, particularly in plants, which frequently hybridize).

My biology teacher told me that ultimately, species just means "whatever the experts currently say", because there are so many weird exceptions.

see wikipedia for a more complete explanation.