These photos were taken May 9th.  They are the same pairs of seedlings as in previous posts.  A few days later, I planted them out into the garden.  The seedlings were starting to send out stolons at the base of the plant.  Stolons are sideways shoots of the potato that form tubers when buried underground.  If stolons are left to grow above ground, they will usually become just another leafy stem.  Look for a few stolons in the photos below.