Roots.

They hold the plant in place, keep it in line, hold it up straight.
If a strong wind blows, the roots hold on.
They are essential to the health and growth of the plant.
If the roots are confined in a small pot, the plant will never reach her full potential.
Stuck under the earth, the roots trust the plant is doing her job above.

So down they stay, humble in all their glory; for that is enough to satisfy.