Original Plant of Shosoin “Koboku”

<p>In A. D. 756, 60 drugs were dedicated to the Great Buddha of Todaiji Temple with many treasures and stored in Shosoin (正倉院), a treasure house attached to Todaiji Temple. At present, 38 of the original 60 drugs still remain. The origins of these drugs except "Koboku (厚朴)" and "Kodoritsu (胡同律)" were clarified during the first (1948-1950) and the second (1994-1995) scientific investigations of Shosoin drugs. "Koboku" is a thick bark and resembles modern Koboku (Magnolia Bark, the bark of Magnolia officinalis Rehder & Wilson and its related species) in appearance but not in the following characters: "Koboku" does not have oil cells but a large quantity of druses of calcium oxalate; many lignified phloem fiber bundles piled tangentially; the fractured surface of "Koboku", therefore, is fibrous and multilayered. The descriptions of old Chinese herbal books suggest that several plants were used for Koboku in former times. So, we examined literature on the original plants of Koboku occurring in various places of China to obtain clues to the origin of "Koboku". Accordingly, the barks of magnoliaceous plants (Magnolia spp., Manglietia spp. and Michelia spp.) and Engelhardia roxburghiana Wall. (Juglandaceae) are frequently used as Koboku. In anatomical comparisons of these barks with "Koboku", the bark of E. roxburghiana only possesses the above-stated characters of Koboku. Its appearance also resembles closely that of "Koboku". Thus, "Koboku" is conclusively the bark of Engelhardia roxburghiana.</p>