The wiki states:
Growth Tokens
These tokens are used for all plants and specify growths growing on a plant.
Edible or otherwise usable growths should have [STOCKPILE_PLANT_GROWTH] in their material definitions for proper stockpiling, and must have both [STOCKPILE_PLANT_GROWTH] and [STRUCTURAL_PLANT_MAT] to be picked in fortress mode. This also lets them be collected from plant gathering and farming jobs, unless the growth is linked to the plant itself through a reaction, as in quarry bushes.
And tree tags are in a different section with a primary focus on tree growth and size
The GROWTH_DROPS_OFF tags are only expressed on wild plants. In a farm plot, nothing drops off. The plant is whole until it is harvested, and the act of harvesting turns it into one of its usable parts.
Plants growing in a field are fundamentally divorced from plants growing in the wild, and the tokens that were new as of 40.01 don't apply to farming. Hell, it wasn't until 40.14 that plants with growths were farmable - originally, planting blueberry seeds would grow only a useless "blueberry bush" object.
You think what you want to change is plants, but you're incorrect. What you want to change is
farming mechanics. Which is great: farming mechanics are outdated and don't really make sense with the way plants work now. But you're not going to find a solution to farming mechanics in the plant raws.