Sappanwood, the red wood of the Southern Seas

Su Mu reads « the wood of Su ». The full name was Su Fang Mu, and Li Shizhen gives its origin: there was a country called Su Fang in the Southern Seas, where this wood came from. The heartwood is used, stripped of bark and white sapwood, from a small evergreen tree with yellow flowers native to South-East Asia; in China, Guangxi is said to give the best. Its sign of quality is simple: the deeper the red throughout, the older the wood.

Before entering the pharmacopoeia, this wood was a dye: under the Tang, it coloured the robes of fourth-rank officials crimson, and for a long time it was among the largest goods imported into China from South-East Asia.

Getting the Blood moving again, without warming

In Traditional Chinese Medicine, sappanwood is neutral, with a sweet, salty and pungent flavour. Saltiness reaches the level of the Blood, pungency disperses, and neutrality leans neither towards hot nor cold: a rare trait among substances that move the Blood. It is associated with the Heart, which governs the Blood, the Liver, which stores it, and the Spleen, which produces it. Its core action is to make the Blood circulate and undo stasis, that congealed Blood which, according to tradition, blocks the passage of Qi and fresh Blood.

A matter of measure

An old saying, the one most often quoted about it, states that « in a small amount it harmonises the Blood, in a large amount it breaks it up »: it is one of the rare substances of which tradition says the quantity changes the action itself, not just its strength. According to TCM, where circulation is free, nothing tightens; by setting moving again what had congealed, the wood addresses the cause. It is readily combined with ginseng, which supplements the Qi while the wood disperses, or with Sichuan lovage. Modern research is looking in particular at brazilin, its colouring compound.