Her theme is texture. Turning to my trusty iMac dictionary dashboard widget, it's defined as "the feel, appearance, or consistency of a surface or substance" (italics added) and further defined under the category of art as, "the tactile quality of a surface of a work of art."
While it seems so "random" to be posting photos of grass, looking through my most recent photos, these seem to jump out at me for that theme. The frost-covered blades of grass seem to have a tactile quality to them. They appear brittle and rough, but delicate and breakable at the same time. Hence, the textural quality to satisfy the theme. How fun! :)