The origins of Japanese cherry species

Discussion in 'Ornamental Cherries' started by SoCal2warm, Mar 27, 2019.

  1. SoCal2warm

    SoCal2warm Member

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    Olympia, WA
    Are sweet cherries in the same species as flowering cherries? I have actually done some research into this, and it turns out the answer is very complicated, it's not an easy yes or no question, for a variety of reasons. As it turns out, it is possible to crossbreed sweet cherries with flowering cherries, and importantly the second generation offspring will be fertile (that's not the case when sweet cherries are crossed with sour cherries). The reason generally has to do with chromosome count. Sweet cherries have 16 chromosomes. Wild Japanese flowering cherry trees also have 16 chromosomes. Black cherries and sour cherries, on the other hand, have 32 chromosomes. (There are also several ornamental cultivars in Japan which resulted from hybridization, which have 24 chromosomes) If you crossbreed sweet cherries with sour cherries, the resulting hybrid tree will have 24 chromosomes, and will still be able to produce fruit, but the seeds will be sterile (like breeding a horse and donkey together resulting in a mule, there will be no third generation).

    Many ornamental cherry varieties such as 'kanzan' resulted from hybridization many hundreds of years ago and are sterile, they will not produce any fruit. One of the indicators that a cultivar will be sterile is if it has blossoms are double-flowered (2 rows of petals). This phenomena is common in other species as well (such as the yellow cotton tree, for example). (This might not always be the case however, but is an indicator)Particular cultivars of cherry are propagated by cuttings, so the fact that they cannot produce seed does not matter.

    By far the most common ornamental cherry variety is Yoshino. I was watching a documentary and there was an elderly Japanese expert who lamented that Yoshino is not really a natural variety. Wild cherry blossom trees in Japan do produce tiny drupelet fruits. They are not very edible (the birds like eating them though). But the Yoshino cultivar is a terrible pollinator, it does not even attract bees. Those little fruits often cannot even form when there is inadequate pollination.

    For anyone who may be interested, I came across a published reference to Prunus campanulata being crossbred with sweet cherries. Here is the excerpt:

    "Since there is no low-chill germplasm avaialable for sweet cherry, the only other alternative is to go to another species of cherry for this trait. Several species have been used in crosses with sweet cherry with occasional success with Prunus pleiocerasus and Prunus campanulata. In 1957, W.E. Lammerts made a cross between P. pleiocerasus and P. avium 'Black Tartarian'. This hybrid is very low-chilling (<200 CU ) but not self fruitful. The hybrid was repeatedly crossed with sweet cherry and P. campanulata. In the mid 1970s, the Florida program developed several seedlings by using mixed pollen (P. campanulata and 'Stella'). All the hybrids had pink blooms and thus were probably hybrids with P. campanulata. Several of these seedlings were fruitful. Although the size is still small, this germplasm is useful for the development of low-chill sweet cherries."

    Temperate Fruit Crops in Warm Climates, edited by Amnon Erez, p216

    Prunus campanulata is the Formosan cherry, called kanhizakura in Japanese. It is distinct from the other cherries with its deep magenta colored blossoms. Several hybrids of kanhizakura with other Japanese flowering cherries exist: kanzakura, okame, and youkouzakura being the three most prominent. The Formasan cherry is remarkable for being the only flowering cherry not originally native to Japan, and its ability to thrive in the Southernmost part of Japan where there is very little chill.

    There are nine different varieties of cherry that grow in the wild in Japan, from which all other cultivated flowering cherry varieties originate:

    Yamazakura (Prunus jamasakura)

    Oyamazakura (Prunus sargentii)

    Kasumisakura (Prunus verecunda)

    Oshimazakura (Prunus speciosa)

    Edohigan (Prunus Ascendens spachiana)

    Mamesakura (Prunus incise)

    Choujizakura (Prunus apetala) (means "clove cherry" because blossoms have a faint odor of cloves)

    Minezakura (Prunus nipponica)

    Miyamazakura (Prunus maximowiczii)

    Japanese cherries are believed to have originated, on an evolutionary timescale, in the Himalayas, but they had become indigenous to the Japanese islands before the first peoples arrived. Flowering cherries also existed in China but flowering "plum" - actually closer related to apricot - has always been much more popular there than cherry, this probably has a fair amount to do with climatic considerations.

    Some of you may be wondering about grafting. Can you graft Japanese flowering cherry onto Sweet cherry (Prunus Avium) ?
    The answer is yes you can. In fact flowering cherry is commonly grafted onto P. avium rootstock by many nurseries to dwarf it. My personal opinion is this is probably not the best for the tree in the long term, it will cut the tree's lifespan short. Both sweet cherry and flowering cherry can eventually grow to become quite big if grown on their own roots (not grafted), the size of an oak tree. It is also possible to graft sweet cherry onto sour cherry, but they are generally not considered graft compatible (have poor compatibility). A big part of this may have to do with differing growth rates, since sweet cherry grows much faster than sour cherry. If the rootstock side of a graft union outgrows the scion, the scion will wither and eventually die. Graft incompatibility can take 2 or 3 years to show up. A scion with very poor compatibility will be unhealthy and severely dwarfed.

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