I have just added Pine-Needle Milkweed (Asclepias linaria) to my Wildflowers of Tucson, Arizona website.

Pine-Needle Milkweeds can be found growing on rocky slopes in the upper foothills around Tucson, Arizona, and a good place to observe them is at Molino Canyon Vista Overlook off of Catalina Highway. Pine-Needle Milkweeds are quite common here, and the short nature trail conveniently has a sign to identify them.