Guikao 桂考

Guikao 桂考 is a book on cinnamon written during the late Qing period 清 (1644-1911) by Zhang Guangyu 張光裕.

The brief book was written according to Zhang's own experience and inspection of the regions where the cinnamon tree (Cinnamomum verum) is growing, mainly Chenzhou 郴州, Hunan. He also consulted medical experts about the medical use of the tree. The Guikao, finished in 1889, describes the environment where the tree grows, markers of quality, colour and fragrance (with classes like tianchun 田醇, tianhou 田厚 or tianxin 田馨), harvest, storing and the use of the bark.

It was first printed in 1891 by the Xiangxia Studio 湘霞仙館 and in 1925 published in a joint print with the sequel Guikao xu 桂考續, written by Huang Renheng 黃任恆 (1876–1953). It is part of the series Xushuke zazuan 續述窠雜纂.