GMAT Verbal Section | Re: Use of THE after Verb-ing ?

I would appreciate if someone could explain to me how "the" changes the meaning here, perhaps with another example.

"She is the most dedicated gardener on the block, every day wateringthe more than 50 plants in her yard".
"She is the most dedicated gardener on the block, every day watering more than 50 plants in her yard".
"She is the most dedicated gardener on the block, every day watering more thanthe 50 plants in her yard".

I understand that the