The main structural evidence that the ferns, gymnosperms, and angiosperms evolved from an ancestor that was not an ancestor to the other plants is that all three groups have all have vascular tissue . Since this evolutionarily derived trait is not found in other plants, it provides evidence that these groups all evolved from an ancestral species (the species you selected) which evolved this trait.
Vascular tissue, as shown in the following figure, is tissue that transports fluids throughout the plant's body. It allows water to get from the roots to all parts of the plant, and transports sugars produced by photosynthesis from the leaves to the rest of the plant.
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