Our friend Liz provided a lovely photo of hydrangea, or ajisai in Japanese. Their blooms coincide with rainy season and thus symbolize it. According to Wikipedia, their flowers can be white, blue, red, pink, light purple, or dark purple according to soil acidity. I have heard that hydrangea flowers are also very unusual in their ability to change color as they age, sometimes passing from a white through blue to purple stage - though I can’t vouch for this veracity. I have noticed that the hydrangea flowers in my local park which were white a few days ago are now blue, though, so unless someone replaced the shrub with one the same size, I suppose it must be true. Thank you, Liz!