Your plant equivalents could turn motion into electrical charge via piezoelectricity.

https://en.wikipedia.org/wiki/Piezoelectricity

Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat. It is derived from the Greek πιέζειν piezein, which means to squeeze or press, and ἤλεκτρον ēlektron, which means amber, an ancient source of electric charge.

https://contest.techbriefs.com/2014/entries/sustainable-technologies/4092

Your wind plants would use piezoelectricity to concentrate charge in a small area. Ions then move into / out of that area in response to charge differential, and this movement can be harnessed to generate ATP. This is how chloroplasts work, using sunlight to split water and produce charge differential.

The trick will be to harness wind energy captured on a large scale (by flexing stems?) to produce charge and generate ATP. Mitochondria and chloroplasts are little but maybe the energy generating organs of these plants would be considerably larger. Given that many piezoelectric substances are crystalline, the energy organs of your dark wind plants might be jewels.