It would have been something like 2005 or so. It may have been a known fact at the time, but they mentioned specifically that they were caught by surprise by the phenomenon. I didn’t fault them for it - the whole project was kind of a mess. I’m a biologist and I wasn’t aware of that, so it wouldn’t have occurred to me, either.
That’s weird though. You’d think they would have had multiple botanists on the design team who could have pointed that out.