Prunus maackii, the Friends’s Dividend for 1986 Gregory j. Waters Friends of the Arnold Arboretum receive the exceptionally cold-hardy Amur chokecherry as a benefit of membership All members of the Friends of the Arnold garden in St. Petersburg (now called Lenin- Arboretum will be receiving ready-to-plant grad). This was the first recorded introduc- seedlings of maackii in late April or tion of the species into the United States. early May, as this year’s plant dividend. In Prunus maackii was not introduced into mid-April, staff members and volunteers Britain until 1910. working in the Dana Greenhouses shipped Though the Amur chokecherry produces the six- to twelve-inch seedlings by U.S. small racemes of white (see the back mail. Recipients who live farther north than cover of this issue of Arnoldia) and pea-size Boston will be pleased to learn that the spe- dark-purple , the main ornamental cies is hardy to at least minus 35 degrees attraction is its bark. Golden brown and Fahrenheit. Unfortunately, Prunus maackii glossy, it peels off in thin strips when mature. does not perform well south of Zone 6 owing Lit by afternoon sun or seen against a back- to the stresses of summer heat. drop of snow, the beautiful bark of Prunus The common name, Amur chokecherry, maackii is an unforgettable sight. refers to the species’s native habitat along Few Friends of the Arboretum can have the Amur River in northeastern China (Man- missed the prominent pondside planting of churia) and southeastern Soviet Union. Prunus the species adjacent to the new Bradley Rose maackii is native to parts of as well. The Flora of the U.S.S.R. states that Prunus maackii occurs in the "[t]aiga, mixed forests, rare in conifer forests and even more rare in purely broad-leaved forests, often on moun- tain slopes, in illuminated sites, along streams, forest edges and clearings, and coarse rock taluses." Its history at the Arnold Arboretum goes back 108 years, to 1878, when the Arboretum was in its infancy. During the summer of that year, the Arboretum’s first director, Charles Sprague Sargent, and Asa Gray were actively consulting with Frederick Law Olmsted on the preliminary plans for incor- porating the Arboretum mto the City of A close-up ghmpse of the shmy bark of Prunus maackn, showing how it charactensucally peels away m thin Boston’s park system. That year, of sheets. Photograph by Hamson L. Flint. From the Prunus maackii arrived from the botanic Archives of the Arnold Arboretum. 12

Ttvo snow-covered specimens of Prunus maackn m the Arnold Arboretum Photograph by Albert W. Bussemtz. From the Archives of the Arnold Arboretum.

Garden. These are descendants of seeds of equal parts of sand and perlite, and kept in collected by the Russian botanist B. V. the humid atmosphere of a mist bench or Skvortzov from a forest east of Harbin, Man- enclosed m a plastic bag, the cuttings should churia, on September 19, 1939. Skvortzov have roots within ten to twelve weeks. sent the seed to the United States Plant Intro- Seedlings should be kept cool until they duction Station at Glenn Dale, Maryland, in are planted outdoors, preferably in mid-May. January 1940, where they were assigned They should be planted in sites with mod- Plant Introduction Number 135617 and erate to full sun, m well drained soil. Young planted. In 1961, scion material from the trees should be staked for the first two or Plant Introduction Station trees was sent to three years so that their shallow roots can the Arnold Arboretum, where it was grafted become firmly established. onto Prunus serrulata rootstalk and given Pruning and controlling insects and dis- Accession Number 388-61. Vegetative cut- eases should be easy with the Amur choke- tings from these grafted trees yielded the . During the early years, structural trees we have today. Because of their distinc- pruning performed in late winter corrects the tive glossy bark, which can be viewed year ’s naturally small branching angles and round, they are among the most commented- improves its overall shape. Proper care and upon trees in the Arboretum. maintenance keep insect and disease prob- The Arboretum’s records indicate that lems to a minimum. Prunus maackii can be propagated by seeds, cuttings, and grafts. (See Alfred J. Fordham’s detailed article on the propagation of Prunus maackii below.) Perhaps the easiest method Gregory J. Waters has worked as a horticulturist m Hol- of propagation for the general gardener would land, England, and Pennsylvama, and at the Arnold where he has been an mtern m both be to take semi-hardwood stem cuttings in Arboretum, plant propagation and horticulture. Currently a graduate stu- and to treat them with an 0.8 per- mid-July dent m ornamental horticulture at Cornell University, cent indolebutyric acid dip or with an equally he has previously wntten for Horticulture and Amencan strong powder. Placed in a rooting medium Nurseryman, as well as for Amoldia