The Mimosa tree (Albizia julibrissin), also known as the Persian Silk Tree, is a deciduous species recognized by its distinctive, vibrant summer flowers. Its bark has been traditionally used for various properties in different cultures. Harvesting the bark requires a careful approach to ensure the material retains quality while promoting the host plant’s long-term health. This guide provides instruction on how to safely and effectively gather this botanical material.
Identifying the Correct Tree
Before harvesting, positive identification of Albizia julibrissin is mandatory to distinguish it from potentially toxic look-alikes. The leaves are a primary identification feature, appearing as long, frond-like structures that are bipinnately compound. This structure means the main leaf stalk is divided into secondary stalks, each bearing numerous small leaflets, giving the foliage a delicate, feathery appearance.
The flowers are the most recognizable trait, blooming in late spring or early summer as dense, fluffy tufts of pink filaments resembling powder puffs. The bark of a young tree is typically thin, smooth, and greenish-gray, becoming slightly furrowed and gray-brown as the tree matures.
Optimal Timing and Ethical Sourcing
The quality and ease of bark removal depend on the time of year. Late spring to early summer is the optimal period for harvesting because the tree’s sap is actively rising, a phenomenon known as “slipping the bark.” When the sap is running, the inner bark layer separates easily from the woody core, minimizing effort and reducing damage to the tree.
Responsible harvesting dictates that material should only be taken from a healthy, mature specimen, and never in a way that endangers the tree’s survival. It is recommended to only harvest from branches that are already dead or freshly pruned, or to utilize fallen limbs.
When harvesting from the main trunk or a large limb, removal must be limited to a small, vertical strip that does not encircle the entire circumference. Removing a ring of bark completely around the trunk or branch (girdling) severs the tree’s circulatory system and leads to death.
For sustainable removal, take a strip covering no more than one-third of the trunk’s circumference. This allows the remaining bark to continue transporting nutrients, enabling the tree to compartmentalize the wound and begin healing immediately. Material from trees slated for removal, such as those interfering with construction, represents an ideal and ethical source.
Step-by-Step Bark Removal Techniques
Specialized tools make the removal process easier and cleaner: a sharp utility knife, sharp pruning shears, and a clean collection container. Always wear gloves and ensure tools are sharp to make precise cuts. Focus initially on harvesting from smaller limbs (one to three inches in diameter) or from a vertical strip on a larger trunk section.
To begin, use the knife to make a shallow, circumferential cut completely around the limb or trunk section where you plan to start and stop. The cut must penetrate the outer bark and the phloem layer, reaching the cambium, but should not cut deeply into the wood. Next, make a single, straight vertical cut connecting the two circumferential lines, creating a removable section.
With the bark “scored,” begin physical separation using a blunt, thin tool like a bark spud or the dull side of a knife blade. Gently pry the bark away from the wood, starting at the edge of the vertical cut. The inner bark (phloem) is the desired layer, located directly beneath the outer bark.
When harvesting from a larger trunk, remove the outer bark and phloem while leaving the thin, moist cambium layer adhered to the wood. This cambium layer is the living tissue responsible for the tree’s growth and healing. Removing bark only in small vertical sections allows the tree to seal the wound and prevent infection. Once separated, use the pruning shears to cut the strip into smaller sections.
Post-Harvest Preparation and Storage
Immediate preparation is necessary after removal to ensure preservation and quality. Begin by carefully scraping off any remaining rough outer bark, moss, or debris from the harvested pieces using a clean knife or brush. The goal is to isolate the desirable inner bark, which contains the highest concentration of active compounds.
The bark pieces should then be cut into small, uniform lengths, typically one to two inches long, to facilitate thorough and even drying. Proper drying reduces the moisture content below 10%, preventing the growth of mold and mildew during storage.
Spread the prepared bark pieces in a single layer on a drying screen or clean paper in a warm, dark, and well-ventilated area. Avoid direct sunlight, as this can degrade the chemical constituents. Ensure air circulates freely around the pieces.
Depending on humidity and temperature, this air-drying process may take several days to a week. The bark is sufficiently dry when it snaps cleanly instead of bending. Store the dried material in an airtight glass jar or container, placed away from direct light and excessive heat, to maintain potency.