Crassula ovata, also known as Jade Plant, may be the most popular plant in San Francisco. You see them EVERYWHERE - outdoors, indoors, on porches, even growing from cracks in the street. They are tenacious little oddballs, which bloom beautifully in August once mature. Outdoors they are more or less impossible to kill. Indoors, make sure they have access to very bright light, and allow the water to dry out all the way between waterings.
