Prunus × nudiflora

Prunus × nudiflora (king cherry, 왕벚 wangbeot, 왕벚나무 wangbeonnamu or 왕벚꽃 wangbeotkkot) is a Korean native cherry tree originating from Jeju Island. It is a distinct species from Japanese native Yoshino cherry. King cherry is a rare plant and listed as an endangered species. As of April 2017, 194 king cherry trees were growing around Mt. Halla in Jeju Island. According to Gen-ichi Koidzumi, king cherry is erroneously believed to be discovered by a French missionary Émile Joseph Taquet although what he discovered was a different species.
There have been disputes over the origin of king cherry and Yoshino cherry. Both are suspected hybrids, with doubts about the parent species. In 2007, a study conducted on the comparison of king cherry and Yoshino cherry concluded that these trees were categorized as distinct species. However, South Korean media assert that king cherry is the same species as Yoshino cherry. In Korea most of the places for cherry blossom festivals, including Yeouido and Jinhae, are still planted with Japanese Yoshino cherry trees.
In 1901, Yoshino cherry was given a scientific name Prunus yedoensis by Jinzō Matsumura after its place of origin Yedo (current day Tokyo). In the early 1900s, king cherry was thought to be the same species as Yoshino cherry, it is called Prunus yedoensis, the same scientific name as Yoshino cherry. After Ernest Henry Wilson suggested Yoshino cherry is a hybrid between Prunus subhirtella var. ascendens (Edo higan) and Prunus lannesiana (Oshima zakura) in 1916, Yoshino cherry came to be called Prunus × yedoensis. However king cherry still remained to be called Prunus yedoensis which is originally given to Yoshino cherry. In 2016, Katsuki et al. proposed a new name Cerasus × nudiflora after king cherry was found to be a hybrid by Cho in 2014 and shown to be genetically distinct from Prunus × yedoensis.
The Korean name wangbeonnamu (왕벚나무, king cherry) was created in 1963 when the Korean official plant resource survey team found three trees, until then it was called sakuranamu (사쿠라나무, sakura) or teolbeonnamu (털벚나무, hairy cherry). Wangbeonnamu means "king cherry tree" while wangbeotkkot means "king cherry blossom". The Korean name wangbeonnamu or wangbeotkkot does not distinguish Yoshino cherry from king cherry because they have been thought to be the same species. If necessary, Yoshino cherry is referred to as someiyosino (소메이요시노), a transliteration of a Japanese name for Yoshino cherry.
King cherry is quite rare in number in its habitat. In 1908, a single tree was discovered in the north slope of Mt. Halla near Gwaneumsa Temple by Taquet although according to Koidzumi it was a different species. In 1932, Koidzumi discovered a single tree in the south slope of Mt.Halla. In 1962, the first Korean official plant resource survey team was established and found three trees. Next year in 1963, the team found another three trees. In 1965, Han Chang-yeol reported that wild cherry trees which grow in Mt. Halla in Jeju Island are mostly Prunus subhirtella var. pendula form. ascendens (Edo higan) and Prunus donarium (Yamazakura) and king cherry is rare in number, around 10 individuals, having been found in a half century. In 1998, Kim Chan-soo reported that 33 king cherry trees were found around Mt. Halla. From March 2015 to October 2016, Warm-Temperate and Subtropical Forest Research Center, Korea Forest Research Institute conducted a survey of king cherry on Mt. Halla. The center found 194 king cherry trees are growing in 173 locations. The trees are located at altitudes between 165 m and 853 m. The trees range 5–19 m in height, 15–145 cm in diameter and 15–265 year old.
King cherry is morphologically similar to Yoshino cherry. When Yo Takenaka went to the Jeju Island in 1933, he observed that the king cherry's hairs on calyx lobes and on the lower side of leaves were less numerous, and the peduncles were shorter. In 1998, Chan-soo Kim studied the morphological variation on 18 characters in flowers, leaves, fruits, and seeds. Most characters of king cherry were smaller in size than those of Yoshino cherry although the limits of variation of the characters were somewhat wide in king cherry. The most prominent difference is that the calyx tube of Yoshino cherry is cup-shaped, whereas it is wedge-shaped in king cherry, in addition, the inflorescences of Yoshino cherry are corymbose while those of king cherry are umbelliferous.
As of 2017, most of the cherry trees planted in South Korea are Yoshino cherry trees known to have come from Japan or have been grafted from trees planted during the Japanese colonial period. In hopes to replace these trees with Korean native king cherry trees, efforts are undertaken to propagate the excellent varieties of king cherry.
In 1996, the Timber Breeding Research Institute, former Warm-Temperate and Subtropical Forest Research Center planted 40 king cherry trees artificially bred by the tissue culturing. They bloomed in 2003 for the first time. The Warm-Temperate and Subtropical Forest Research Center has developed a conservation area of 90,000 m since 2000 and is now cultivating 3,000 king cherry trees. In April 2017, the center announced that it has developed 100,000 m of king cherry tree cultivation farm at Hannam Experimental Forest and planted 4,150 four to five year old king cherry trees. The center plans to expand the area to 250,000 m by 2022 and to cultivate a total of 20,000 king cherry trees.
King cherry tree habitats are designated to the Natural monument. There are three Natural monuments.
Koehne described the variation of Prunus yedoensis var. nudiflora from Yoshino cherry when he proposed a new variation Prunus yedoensis var. nudiflora.
According to Park Man-Kyu (1965), king cherry trees found until 1965 are as follows:
According to Koidzumi, he found a king cherry and an Eishu zakura (Prunus yedoensis var. nudiflora) not two king cherry trees.
According to Takenaka, the tree he observed was the same tree Koidzumi found.