Botany is the scientific study of plants, plant organisms, and how they function. Most botany majors in college either continue on to receive a masters or Ph.D. in botany or go on to med or pharmacy school.
Joe was a botanist for a while, and then decided to get his pharmaceutical license.
In any "plant the bomb in the enemy base" type gametype such as Sabotage in an online multiplayer 1st person shooter, in this case Call of Duty 4, botany is the act of running into enemy territory and heroically planting the bomb while under enemy fire ("Planting" the Bomb, thus Botany).
There is a certain amount of skill involved in this endeavor, and only the most skillful Botanists can achieve the highest title of the field, Grandmaster of Botany.
The Masters of the Botanical Arts (Botany) are able to slip in with a well-placed smoke grenade and arm the bomb with the entire enemy team still alive, avoiding a barrage of bullets and most likely an air strike right on top of the target. They then proceed to protect their "plant" and will most likely die in the bomb explosion, presumably taking a few of the opposition with him.
A place a person would prefer not to live in, an area in which mentally, physically or emotionally diturbed people - if you can call them that - reside
I hate Botany, never go to Botany