Variation on a Theme

Originally from India and found in most of the US, this velvetleaf wildflower produces the engorged, 1-inch-wide seed pod to the right, which dries and splits along its ribs, releasing perhaps a half dozen dark, round seeds from each bulge.
The green spikes harden into pin-sharp defenses as the seeds ripen and the pod dries, presumably discouraging predation. Because the pod resembles the crimped edge of a pie crust, its alternate name is pie-maker.
This bushy plant grows about four feet tall among burdock and assorted tall grasses at the edges of local fields.