While in the Peace Corps in Latin America, I learned the Spanish word for bark, which is "cascara." So, when I came across a description the other day of the "cascara tree," it piqued my interest. My old 1962 forest products textbook says that the "cascara tree" (Rhamnos purshiana DC) grows in the Pacific Northwest and neighboring Canada.
A member of the Buckthorn family, it grows up to 20' - 40' tall, 15" in diameter, and its bark produces one of the most important natural drugs in North America. It is sold internationally under the name "Cascara Sagrada" which is Spanish for sacred bark. The bark is used for laxatives and tonics and has to be harvested by cutting the tree down during the growing season -- from mid April to the end of August. Regeneration and future crops require leaving unpeeled stumps at least 6" high and cut at an angle to impede moisture intake and rot. The stumps sprout and grow to a harvestable tree in about 15 years.
A good peeler can strip 250 pounds in a day, which includes branches down to 1" in diameter. The bark should be collected during dry weather. Bark cleaned of lichens and moss commands a higher price.
Dry bark weighs half of what green does and sells for three times more. It dries best out of the weather in well-ventilated sheds as dew and rain dampen the drying process and direct sunlight can cause staining. It should be cured for at least one year and then is chopped up and put in burlap bags weighing 50 - 75 lbs.
In the 60's, supplies were running low and plantations were started -- specifically in Oregon. However, like any orchard, care and maintenance were required. Fencing was necessary as critters like deer, cattle and even mountain beaver like to munch it.
It was estimated that a tree would produce 12 - 16 lbs. of bark after 10 - 15 years, which translates into a yield of about 10,000 - 15,000 lbs. per acre. Way back in 1957, dry bark sold for 20 cents per pound.