The elderly represent the largest medical marijuana consumer group. However, more and more senior citizens are turning to marijuana for recreational purposes — and it’s not just the aging baby boomers that left the substance behind in college. Some retirees are trying marijuana for the first time. In 2011, the National Survey on Drug Use and Health found that 6.3% of adults between the ages of 50 and 59 used marijuana, more than double the percentage that reported it 10 years ago. HuffPost Live streamed…