Will a Thundercloud Plum Pollinate Satsuma?

The Right Pollen

• Cross-pollination is a natural mechanism for maintaining greater genetic diversity because the offspring of cross-pollinated species receive a mixture of traits from two dissimilar parent plants. (see References 3) The flowers of a self-unfruitful plant will not allow themselves to be fertilized by pollen that they recognize as originating from the same plant or a plant of the same variety. (see References 4, page 1) Pollen can be transferred in a variety of ways, but for tree fruits, pollination is largely dependent on bees. (see References 4, page 1) Bees in this case are termed the pollinators, and the tree that provides the pollen is known as the pollinizer. (see References 4, page 1)

The Right Species

• A species is commonly perceived as a group of organisms that are very similar in appearance, but the scientific definition of "species" is actually more precise: a species includes all of the organisms that are able to reproduce with each other. (see References 5) As a general rule, breeding is impossible among members of different species. In the context of fruit trees, this means that only trees within the same species can cross-pollinate. You can quickly determine the species of any plant by looking at its scientific name. The first word indicates the genus, and the second word indicates the species. E.g., Prunus domestica -- Prunus is the genus and domestica is the species name. (see References 6)

The Many Species of Plums

• Common names for plants are often imprecise, and this is certainly the case with plums. The generic term "plum" includes trees belonging to over 100 different species. (see References 2) The standard edible plums are Prunus domestica, commonly known as European plums, and Prunus salicina, commonly known as Japanese plums. Both of these species are adapted to U.S. Department of Agriculture hardiness zones 5 to 9. Thundercloud flowering plum tree (Prunus cerasifera 'Thundercloud') is a different species from the Japanese plum variety 'Satsuma' (see References 7, References 2). Consequently, 'Thundercloud' cannot serve as a pollinizer for 'Satsuma'.

A Match for Satsuma

• 'Satsuma,' along with most other Japanese plums, needs to be cross-pollinated by a tree from a different Japanese plum variety. Recommended pollinizers for 'Satsuma' are 'Santa Rosa,' 'Shiro,' and 'Burbank.' (see References 8, page 2) These compatible varieties should provide flowering periods that overlap, which ensures that the flowers of one variety are receptive to pollen while the flowers of the other variety are shedding pollen. Bees will not transfer enough pollen between trees that are far away from each other, so do not separate the two cross-pollinating varieties by more than 100 feet. (see References 4, page 1)