How do Janina and Misha react to the milkweed plant?

From the text:

It was thrilling just to see a plant, a spot of green in the ghetto desert.

She plucked it from my shirt. She held it by the seed up to the light. She dusted her nose with it and giggled. She brushed the fluff across her cheek, closing her eyes. She stood on tiptoes and held it as high as she could and let it go. It sailed toward the sky.
“That’s my angel,” she said.