Thanks, and I'm still waiting to know which pronunciation I should use.
Good idea, tdol, that you'll check with a keen gardener!

or maybe a horticulturist?
Janaina, I'm also using the Longman Dictionary. It gives both pronunciation and either one is correct. I'm just not too happy with my son's teacher who INSISTED that it should be 'he' biscus.
Either she proves me wrong or I'll prove her wrong!