Article (magazine)  (Jan 1955)  Page(s) 17.  
 
In Nara and in Yamata there was a variety called "Thousand Petals," and there were stories of plants selling for a hundred ounces of silver, and of a black peony, 'Kurobotan'. Wilson believed many of these stories were copied from older Chinese stories such as have been mentioned before. (There is, however, a modern Japanese deep crimson-purple variety named 'Kuro-botan.')

Article (magazine)  (Jan 1955)  Page(s) 58.  
 
Alphabetical Check List of Tree Peony Names In  Public Collections And/or Available in Nurseries 1954-1955
Japanese, Crimson, 'Kuro-botan' (Black Peony) (Jap. bef. 1896), [Gardens] Scott Foundation, [Nurseries] Cottage Gardens, Tingle Nursery Company

Website/Catalog  (1898)  Page(s) 13.  
 
Peonies.
Paeonia Mouton. Tree Peony.
This plant is already well-known to the West. Flowers in May, widely differing in color and form. Stems either shrubby or branched from the foot. The best species are native of central Japan. The flower often attains one foot in diameter. These plants have fanciful names in Japanese, which we give with as nearly as possible the English equivalent.
Double grafted set of 20, no two alike, $4.00. 1 case of 100 peonies comprising 25 varieties, $18.50.
V. Dark Claret to Purple.
Kurobotan, Black Peonies...