*stebh-

The core idea of this root was:

stemming, putting down firmly, a solid stem

The theme is definitely a bit vague, but we can see aspects of it in the English offspring

• step (putting down the foot)
• staff (putting down a walking aid)
• staple (originally, this could be a pillar or tree trunk and even a stairstep – basically something you can rest on.)
• stamp (“put down firmly”)

The word stem, even though it would fit right in here, does not belong to this family and instead comes from a different root.