Book  (Jan 2000)  Page(s) 229.  
 
Kao. See 'Kaow'.
Kaow Tree Peony. ex Japan [no date given]. Also sold as 'King of Flowers'... red

Article (website)  (1998)  Page(s) 1.  
 
The peony 'Kao' (Queen of Flowers) is said to have been imported in the Nara-era [710-794] from China as a medicinal plant. In the Heian-era [794-1185] it was cultivated as an ornamental in temples and the imperial court, but in the Edo-era [1603-1868] it spread among the simple public. It was especially popular in the Genroki to Heoei-era (1688-1711), and specialist books on peonies were published.