Mother
From Wiki Weed
A 'mother' marijuana plant is typically a large, vegetating cannabis plant that has its limbs trimmed off to create clones, which are then grown in addition. Mother plants are what allow growers to produce so much of one strain of marijuana: they could take a half-dozen clones from one plant, grow those clones to fruition, and come harvest you have significantly more pot to sell than if you had only grown and harvested the initial plant. The loss of a mother plant could mean the potential loss of an entire genetic line of cannabis.