Cart-wheel heading off-course into ‘monstrous’ plant (6,4)

'monstrous plant' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps you can see a link between them that I can't see?

'cart-wheel heading off-course' is the wordplay.
'cart' becomes 'drag' (synonyms).
'wheel' becomes 'O' (O looks like a wheel).
'heading off' means to remove the first letter.
'course' becomes 'entree' (course of a meal).
'entree' with its first letter removed is 'ntree'.
'drag'+'o'+'ntree'='DRAGON-TREE'

'into' is the link.

Can you help me to learn more?