PEONIES, The Manual of the American Peony Society, ed. by James Boyd, Copyright 1928 by American Peony Society: Tree Peony Check-list.
Henry & Lee, Japanese Importers, New York, N. Y., 1925.
Nisshoki. (originated in Japan, 1926.) offered by Henry & Lee 1926. (Presumed to be in commerce, 1927.)
The Chugai Nursery, Yamamoto, Japan, Catalog 1940-1941: Tree peony, Tree peony, Winter-Flowering Peonies, (Everblooming Peonies) Winter flowering peonies have their beautiful flowers from the beginning of November till January and again they flower in spring together with ordinary spring flowering peonies, hence the name of ever-blooming peonies. Their flowers are as large and beautiful as spring flowering varieties. There is very rare exception of not flowering in winter. however, but in whitch case it will flower in next winter
Wister (1961):
'Nisshoko' (Flag of the Rising Sun) (Jap. bef. 1934)
