Green willow signified lost love, or being forsaken by a false lover. In Ault's 'Elizabethan Lyrics' is a song or poem about it, five verses, by John Heywood, c 1545 entitled:

All a green willow, willow, willow
All a green willow is my garland.

John Cutts printed a fuller manuscript version of the willow song in Shakespeare's 'Othell' in Journal of the American Musicological Society X, #1 (Spring) 1957. Another version expanded version is on a broadside ballad, ZN2222, in my broadside ballad index. Other songs using the green willow motif as can be found in the broadside ballad index by searching on 'willow'. Burl Ives used to sing one, "How now shepherd what means that, Why wearst willow in thy hat".

From "A Nosegay always sweet" in 'A Handefull of Pleasant Delites', 1584:

Sage is for sustenance..
Rosemary is for remembrance...
Thyme is to try me...
Marigold is for marriage..
+ others

In "Love in a Maze", ZN1606:

She stuck the bush of May in the Time and did present it
Unto this young man, which was so discontented....

This May stuck in Time which is to me presenting
Shews that I may, in time gain your love with sweet consenting.