On the willows there, we hung up our lyres

There is something reassuring about that choice of metaphor. He's seen Claudius labor over his plants so many times, and he knows how much he cares for all of them, though he has his favorites. Galahad imagines himself a seedling of mimosa that Claudius has transplanted, soft as a globose flower covered in lavender filaments, shy as bipinnate leaves whose leaflets fold inward at a touch.