What endurance? IIRC, the story (not a competition at all) of the oak & the willow is one of Aesop's. Except that it's not the oak & the willow, it's the oak & the reeds! I may have the bendy plant wrong, but the story (in its older forms) is invariably "Why am I, who was so strong, being borne broken down the stream?" "Why, brother? Because I bend before the storm & thus weather it!"

Or words to that effect.