This has occurred to me due to conflict between Fabricate and Blight.
Fabricate says it can not target creatures and lists trees as example targets.
Blight on the other hand can only target creatures and lists mundane normal plants as example targets.
Which of these conflicting spell descriptions is correct?
Note:
It also occurred to me that plants might also be whichever one is convenient, unlikely but possible.
Best Answer
Which spell description is correct?
Both
Fabricate
The description of Fabricate states that:
(Emphasis Mine)
The spell converts raw materials into products and as stated in the description you can make a bridge from trees. That is 100% correct. Trees are considered objects and their wood is a raw material.
Blight
The description of Blight states that:
(Emphasis Mine)
There are two different plants in DnD as I have written below. There are the "creature" or/and "magical" plants and the "object" or "non-sentient" plants.
The creature/magical plants are, as you may have already guessed, creatures. They have stats and abilities just like any other creature in the DnD universe.
The object/non-sentient plants are, again, non-sentient. For example, the flower inside a flowerpot is not a creature. Anything that cannot do at least one of the following shouldn't be considered a creature:
Move, eat, speak, breathe, see, hear
What are plants: creatures or objects?
Both
Let me explain...
Plant "creatures"
There are plant creatures such as Myconids or Treants who breathe, walk, eat just like any other creature. These are considered creatures. You can find a list of them here.
They have stats and abilities like any other monster in D&D 5e. As stated in the description of the "plant" creature type (Monster Manual, p. 7):
(Credit: MikeQ)
Plant "objects"
There are also 'normal' plants, what we call non-sentient plants such as Trees (Ash, Birch, Oak) or flowers such as Orchids. These are considered 'objects' or non-sentient beings. You can find a list here.
Generally, any plant that doesn't come with a stat block should not be considered a creature.