'No root' is an obvious figure of speech. You've probably used it yourself before. No plant grows without any roots at all.
Recently a giant tree fell over on the land across the road from my house. I was amazed to see it had 'no root'. Of course it had roots (no plant grows without roots), but it's roots were only a few inches long, and so it was not firmly rooted in the ground. And so it is with the word of God that sprang up and was growing in soil #2:
"6Some fell on rocky ground, and when it came up (it was growing), the plants withered because they had no moisture.
13Those on the rocky ground are the ones who receive the word with joy when they hear it, but they have no root. They believe for a while, but in the time of testing they fall away.
The problem was the word of God had no
deep root in the heart of this believer and did not reach deep sources of water to sustain that word in them when the heat of the sun beat on them, and so the word dried up. If you've ever cleaned out trees starting to grow in the gutters on a house you'll see that clearly demonstrated.
The Galatians are a good example of the #2 soil believer.