User:Krisxing/sandbox

Explosive Dispersal
After flowering, the five pericarps on the fruits of Erodium joined together and grow into a spine shape(Galstyan 2018). The awns, which are hair like appendages, of each pericarp joined together. As the fruits dry, dehydration create tension, and elastic energy develops within the awns. The shape of the awn changes from straight to helical, causing them to explosively separate the seeds away from the maternal plant (Stamp, 1989a). During dispersal, mechanical energy stored in specialized tissues is transferred to the seeds to increase their kinetic and potential energies. The energy storage capacity of the pod tissues was determined by their level of hydration, suggesting a role for turgor pressure in the energy storage mechanism.

Self-Burial
The awn on each seed, once on the ground, respond to humidity of the environment and change its configuration accordingly. The awn coils under dehydration and uncoils when wet. This results in motor action of the seed, combined with hairs on the seed and along the length of the awn, moves the seeds across the surface, eventually positioning them into a crevice and causing them to drill themselves into the ground. The coil and uncoil of the awn tails are achieved by the hygroscopic tissue in the active layer on the awns. Hygroscopic movement happens with respond to a change in the water content of dead plant tissue, specifically in the cell wall. Water absorbed by the cell wall bind to the matrix, causing it to expand and to drive the cellulose microfibrils apart, cause the matrix to uncoil, and lead to the uncoil of the awns. On the contrary, the matrix will contract under dehydration, leading to the coil of the awns. Therefore, when the microfibrils are aligned with each other, a change in the humidity of the surrounding environment will drive the cell wall to contract or expand, causing the awns to coil and uncoil. (Elbaum 2014)

Research found no correlation found between weight of the awned fruits and the dispersal distances for Erodium species. However, Erodium species with larger seeds have a longer coil and uncoil time compare to smaller seeds. In the field, the rate of seeds burial declined throughout the season. The larger seeds buried themselves more often than the smaller diaspores. However, larger seed have a hard time finding a good place or big enough place for it seed to be buried. Smaller seeds have easier time finding a hole and drill themselves in, thus are more likely to be buried rather than lying on surface of soil (Stamp 1989). The Advantage of explosive dispersal and self-burial dispersal is to get mature seeds quickly to the ground during the most favorable period for burial by hygroscopic mechanisms.