Seeds from wild wheat are shaped like spears with the length of the shaft split in two. Each half of the shaft has little appendages angled upward, like the threads of a feather but sturdier. The point of the spear—the actual seed—lands on the ground. When moisture in the air shifts, the shaft-halves spread apart as they grow dry, then pull together as they grow damp. This opening and closing gives the little spurs the opportunity to grip deeper and deeper into the earth.

Thus, it’s a seed that plants itself.

(See Smithsonian, July, 2007.)