Straw polls are similarly enigmatic. Auden once said* of the relationship of a poet's biography to his work that it was simultaneously too obvious to need comment (Catullus loved Lesbia) and too obscurely complex to endure analysis. The same goes for these words of grass.
You do not, as Bob Dylan correctly observed, need a weatherman to know which way the wind blows. Shakespeare agrees and adds in The Merchant of Venice that an amateur zephyrologist can manage by:
Plucking the grass to know where sits the wind,
You throw a straw in the air and see which way the wind takes it. Hence a straw vote. Hence a straw poll, which elephantine-memoried readers of this blog will remember is a headcount.
OR, it is simply a weak poll, a poll of straw. Straw has always been weak as in straw dogs and straw men and clutching at straws etc etc which is why you only need hay wire to bind it together.
Grass roots is the third of these frail etymologies. It popped up at the beginning of the twentieth century. The roots I can understand, but the grass seems unnecessary. Why not dandelion roots, which are considerably stronger? English seems to be a strangely graminivorous language. But perhaps that's a good thing: hay fever used to be called summer catarrh, which is just horrible.
Or perhaps it's that grass roots are destroyed by GOATs. Now I'm off to accuse my lawn of informing on me to the police.**
The Inky Fool's summer residence
*In his preface to Shakespeare's sonnets. I don't have a copy to hand.
** A grass hand was a jobbing printer who moved employers, hence the sense of disloyalty, probably. A grass widow is an unmarried woman with a child (although I can't for the life of me see how that could happen). All flesh is grassy, bring on the lawnmower.