|Photo © Marty Horowitz|
You've probably walked right by this plant a time or two. Twin Seed (Dicliptera resupinata) likes a bit of shade; look under other plants (especially along the road into Sabino Canyon).
Click on the photo for a larger view and note the leaves (thin) versus the sepals (spade shaped).(Sepals basically hold the flower to the stem.) The ovary (where the seed forms) is at the bottom of the tube of the flower. The sepals close around the developing seed (see the reddish spot in the middle of the sepals in the lower left) and dry to a tan color (two to the left of the aforementioned).
Twin Seed can bloom year round. Go out and look for some today.