A green filter does lighten foliage, at least to the extent that by subduing the other parts of the spectrum that do not pass a green filter, the greens will be among the brighter items to reach the film.
Had you a subject with bright reds and greens, and a strong green filter over the lens, the reds will be greatly subdued, while the green light will pass to the film unmolested. The net effect is that greens will become dominant where before they were not. With a less strong filter the effect becomes more subtle.
The 58 and 61 green filters are the most common strong green filters used for practical photography - as opposed to scientific. The 58 is a strong green tricolor filter and the 61 is described as a deep green - somewhat stronger. Neither is a subtle filter.
All the strong filters pass their color while suppressing other aprts of the spectrum. The 25 and 29 filters are strong reds, the 29 especcialy so, which will remove almost all green. The 47 is a stong blue which will hold back yellows and reds, and the 47B even stronger.
The 11 is a light yellow-green filter and might be the one another post describes.
A really good primer on what filter will do what to what is at:
www.crime-scene-investigator.net/filters1.html
That page lists what filter will lighten or darken what color.
A broader list of the basic filters for BW contrast and their usage is at:
www.jackspcs.com/filters.htm which also shows rough equivalents between Kodak's Wratten numbers and a couple of other filter numbering systems.
and:
www.kodak.com/global/en/professional/support/techPubs/b3akic/b3akic.jhtml
Saint Ansel's books describe the effects of filters very well.
Best
C