Essential Question : what adaptations can be made to a crawling vine that would allow them to obtain as much energy as a top level consumer if the vine was on a planet 1 au from a sun sized star?
Typical Earth plants convert about 1% of the solar energy into useful "work", which explains why we need about one acre of cropland to feed one person under ideal conditions.
The typical "top" of the food chain creatures are omnivores (like us) or carnivores (like our house cats) gain advantage by concentrating the diffuse solar energy gathered by plants through the mechanism of eating creatures which eat plants (the typical retort to an obnoxious vegetarian is to say "my food eats your food", which summarizes the process).
So your plant would have to somehow become far more efficient at collecting and using solar energy.
The first modification would be to make the energy collection mechanism work at more than one wavelength of light. In a plant, this might require using multiple different molecules of Chlorophyl analogues, so the resulting leaves would be black, as they would absorb light rather than reflecting many wavelengths.
The internal mechanisms of energy collection and transfer would also have to be made more efficient, although our current understanding of photosynthesis is incomplete, so exactly how this would be done isn't entirely clear.
One issue with a high efficiency plant would be waste heat rejection. Absorbing and converting a higher percentage of energy from the sun will potentially heat the internal structure of the cells to the point that biological structures could fail. A highly energy efficient plant might need to invest in some sort of active cooling system. You could imagine a series of leaf like radiators which always turn edge on to the sun and pump hot sap for cooling. In an aquatic environment, plants might have "open cycle" cooling and transpire a great deal of water to reject waste heat. Other mechanisms might be evolved to take advantage of the local environment.
Other adaptations might be to make more use of fruiting or tuber like bodies as energy reservoirs for the plant metabolism, rather than for the seed. In this case the plant could consume the fruit or tubers during periods of winter, in order to remain active and "alert".
What the plant does with the extra energy is up to you, but "warm blooded" plants would certainly thrive in an arctic environment, while regular plants are already adapted to most of the existing biomes of the Earth.
They would essentially need to have high end solar panels converting sunlight to electricity for the needed energy transfer.
Have Dark Plants
Have it be completely black. Black plants absorb more light, meaning less,is reflected to your eyes and it looks dark.
Make Them More Efficient
Make your plants have a more efficient chemical in them, other than the normal clorophyll.
Make the plant have certain growths, coverings, or just parts of the plant which store energy for later use in times of need. In animals, fat would store a lot of energy. You could have something similar in your plants, or draw sustenance from your fruits in time of need.
Don't Kill The Whole Plant
There are some trees, such as a juniper/cedar tree, which, when water is scarce, cuts off nutrients to parts of itself. That way, instead of the entire tree withering, a single limb dries out and dies, allowing the rest of it to go about its business.