Hou Po (officinal magnolia bark) has been used since ancient times, and a wide variety of processing methods have emerged to maximize its clinical effects. Many different adjuvants have been historically used in the pao zhi of Hou Po, including ginger, dates, honey, vinegar, congee, and salt, and many methods such as boiling, baking, soaking, and stir-frying have been documented. At least 14 different processed forms of Hou Po exist, but ginger-processed Hou Po has the broadest use and remains the most common form in clinical practice.
Ginger-processing for Hou Po first emerged in the Northern and Southern Dynasties period, in Lei Gong’s Pao Zhi Lun (Grandfather Lei’s Treatise on Medicinal Processing), and also appeared in Tang dynasty texts. Today, ginger-processing is often achieved by soaking Hou Po slices in ginger juice until the juice is absorbed, then stir-frying the Hou Po slices at low heat until they are dry. Alternatively, fresh ginger slices can be boiled and then bundled Hou Po can be submerged in the water; the Hou Po is then boiled in the ginger decoction until the decoction is absorbed into the bark, then it is removed, sliced, and dried (10 kg of ginger slices are used for each 100 kg of Hou Po). Ginger-processed Hou Po has a darker, deeper color than the crude product.
Hou Po is a bitter, acrid, and warm medicinal that enters the spleen, stomach, lung, and large intestine. It dries dampness and disperses phlegm while descending qi and eliminating fullness. The medicinal power of the crude medicinal is relatively drastic, and its acrid flavor is irritating to the throat; thus, the unprocessed form of Hou Po is rarely used. After processing with ginger, the throat-irritating side-effect is eliminated and Hou Po’s ability to harmonize the stomach is enhanced. It is traditionally said that “Hou Po has a bitter flavor; if not processed with ginger, it prickles the throat and tongue.”
Beyond the differences in pao zhi, differences in the plant part used and the initial processing method after harvest also affects the medicinal nature of Hou Po. Root bark, stem bark, and branch bark are all used, and differences in the drying method and the use or absence of the traditional “sweating” method create differences in the chemistry of the final product. Further explorations into the nature and significance of these differences are necessary for an enhanced understanding of Hou Po.
The Hou Po sold at Legendary Herbs is Hou Po (Jiang), the traditional ginger-processed Hou Po.