I obviously am not a lawyer

Not only am I not a lawyer, I'm not even a very legally-aware layperson. I'm a systems software engineer. But I truly don't understand how an apple can be intellectual property. What branch of intellectual property law covers apples? Are they registered trademarks? Are they copyrighted? Are they patented?

It must be patent law. This article in AgWeek says:

As the university’s lucrative patent on the Honeycrisp was about to expire, the school launched the SweeTango — a cross between the Honeycrisp and its Zestar! — to keep revenue flowing to support its cold-climate fruit research.

According to About.com, plants were not considered to be patentable until 1930, after Luther Burbank had already died.

But somehow he received a number of patents on his plants after he was dead.

Another article on About.com says that plant patents last for 20 years, and give the inventor:

the right to exclude others from asexually reproducing, selling, or using the plant so reproduced.

I guess I should stick to writing systems software :)