I don't think there is an answer, but I can estimate that the Greeks believed that the grass was the replication of Gaia's green hair. Gaia was the earth goddess.
i thought demeter was the earth goddess ;
In Greek mythology, green grass can be symbolically linked to Gaia, the earth goddess, who represents fertility and the nurturing aspect of the earth. The lushness of the grass signifies the abundance and life that Gaia supports. Through various myths and connections with other goddesses like Demeter, grass can be seen as a representation of Gaia's nurturing qualities.
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