Obviously, this is toned paper*, on which I used a 3B pencil and a white pastel pencil.
The greenhouse was a bit too warm, so I wandered back outside (a comfortable 50 degrees) to the nearby Medicinal Herb garden. Most of the plants there are withered and in decay, with lots of dead foliage about, very captivating, and I found a large dried pod on the ground which turned out to be Cynara syriaca, or Wild Artichoke.
A very pleasant way to spend a lunch hour!
*Strathmore Toned Gray sketch paper (400 Series) 50-sheet spiral notebook, 5.5 in. x 8.5in.