The Bug:

Spore blossoms can be supported by non-logical blocks.

Steps to Reproduce:

• Attempt to place some hanging roots on the underside of an iron bar.
  →  Notice how you are unable to do so.
• Attempt to place a spore blossom on the underside of an iron bar.
  →  Notice how you are able to do so.

Information:

This is inconsistent with all other blocks that require support such as buttons, levers, amethyst clusters, etc.