If they AREN'T his parents, and someone planted them in his YARD(hence the garden hose/compost pile), then they are the dumbest guerilla grower ever. And fir3dragon, isn't it a possibility that they DO die every year, and in spring the new seeds(as a result of males and females growing together) just pop, some turn male, some turn female, and they pollinate, create seeds, drop them in the fall, and the cycle of life begins anew? I don't think anyone was trying to say that these particular plants have been there for years...but are perhaps the offspring of the seeds some former pothead homeowner threw in the garden before he moved...