Bois de Arc

On the way home today I pulled into a quick stop down in the black prairie. I saw fruit on the ground and immediately recognized the big grapefruit like balls. (stay with me to the end) They are not for human consumption, but the plant has always interested me. The French called the brushy tree "bois de arc" or wood of the bow. Botanists believe that the original growing region was in the Oklahoma Arkansas area. Native americans used them to make their bows as you may have guessed. The local tribes traded the wood to other tribes out of the area. The plant has spread to several southern states and perhaps some midwestern areas. It grows along fence rows where it bares its long thorns and drops its fruit. Cattle, deer and squirrel will eat the fruit if there is nothing else around and spread the seed with their patties pills and scat.
English speaking pioneers translated bois de arc to bo-dark, board arc or bo-dock. This stuff is one of the hardest woods I have come across. Farmers cut them to use as fence posts, but they nail the fence to them while they are still green otherwise it may be impossible later. This is the only tree when dead and dried that has ever caused sparks to fly from my chain-saw bar.

We have a hardness scale not unlike the one geologists use: examples

"harder than Japanise arithmetic" is that politically incorrect?
"harder than, how do I say, a preacher's anatomy"
"harder than a bo-dock chunk"