Specimen #3: Long-beaked Storksbill, Erodium grunium
The long-beaked storksbill (Erodium grunium) is a plant that wears its seeds on its sleeve — or, technically speaking, its style. A basic component of plant anatomy, the style usually conducts pollen to the ovary, where the fruit often grows. In the storksbill, however, the style extends outward into a needle-like structure. It is on this pole that the magic of fruit happens. Five seeds grow at the base, each attached to a carpel tail, all of which are fused together, around the style,
as the seeds develop. Meanwhile,
moisture is restricted from the conjoined offspring. This causes contraction and a spiraling around the style. Further drying and further twisting, the five filaments split at their seams, and the five tails extricate themselves from each other. The dénoument of the whole choreography is truly an unraveling: the entanglement springs apart, and each of the five spiraling tails propels each of the five seeds, which fall to the ground. Here they continue to tumble and twist, directing the seeds to further recede from the parent plant.
And there’s more. This calibrated design of physics and biology propels the next phase of the storksbill’s life cycle, in a final act that is a stunning feat of patience and propulsion. Having landed on the ground and recomposed in corkscrew formation, the seed waits. If the ground is dry, there is no movement. But, at the first sense of moisture, the spiral begins to unwind. Before long, the sickle-like curvature of the upper tail is propped upright, a position which necessarily angles the seed, obliquely, towards the ground. The tail continues to straighten and, in a sequence of torque and thrust, the seed is slowly screwed into the earth. If the soil becomes dry, the whole process pauses, and the tail resumes its corkscrew configuration.
The seed itself, however, is not drawn up. Instead, the tail is drawn down to protect the seed, which is crowned with a tiny barb. This harpoon assures that the embedding process is not undone. And so the seed waits for moisture to return, at which point the tail’s movement begins again, and the seed is thrust further into the earth. Now deep enough, and damp enough, it’s poised to decorate another concrete landscape.
Addendum: With all due admiration for the storksbill’s fine-tuned response to moisture and optimal germinating conditions, a qualification should be noted. Apparently the seed can be encouraged to perform on alternate terrains: for example, bread. A drop of water on its corkscrew tail is said to send the seed deep into any sandwich. And the plant grows in many climates, providing world-wide opportunities for a science experiment on your next lunch break.