crop:, sapling: or tree: section is a plant: grass, a bush, a flower or a potted plant. It’s placed and used exactly like a prop, with every prop option. The only difference is that the placement hologram is off. Turn it on for one plant with preview: true.
hitbox, a plant gets a solid hitbox worked out from its model, like a prop. For plants that players should walk through, give it interaction boxes only (see Hitboxes).
Plants don’t grow. For plants that grow stage by stage, make a crop.