A mother line is a line you keep on purpose as stock, to start new lines from. Mother is a role, not a stage: a mother line still has its stage and status like any other.
Pro plan
Open the line and choose Make mother line. A purple Mother line badge appears, and Start new line becomes its main button.
Not a mother line takes the role off again.
The Cultures tab shows Mother lines as cards above the list, each with its jars on the shelf and how many lines it has started.
All lines / Mothers filters the list to mothers only. Mothers always sort to the top.
Lines started from a mother say so: βfrom mother TC-000001β.
Archiving a mother line asks twice, and deflasking from one reminds you to leave jars on the shelf.
Mother lines on their own shelf, with the Mothers filter beside the stage filter.
On the phone, the role is under Change status or role on the line.
Mothers are marked in the phone's culture list as well.