Dr. Plantmore was running late to his Botany 101 class.  Rushing out his front door and through his flower garden, the good doctor tripped head over heels on his garden hose! Tumbling through air, he landed face first in the dirt!  His head went smack into the garden hoe! 

Dr. Plantmore was laying unconscious for a few minutes when Miss Lilly came charging over, from across the street, to see if the professor was all right.   Dr. Plantmore slowly came to, but he was rambling on and on about being late for his class.  As Miss Lilly talked with him she noticed one horrifying fact, Dr. Plantmore lost his memory!  He couldn't teach his class, because he couldn't remember ANYTHING about plants! 

What are the most important basics plant facts that Dr. Plantmore must know in order to teach Botany 101?