A Sino-American Sampler

A Sino-American Sampler Stephen A. Spongberg Plants from the 1980 Sino-American Expedition are finding their way into the living collections of the Arnold Arboretum. Ten years ago this spring, as the intensifying The results of the 1980 Sino-American rays of the sun streamed through the Dana Botanical Expedition have been presented in Greenhouses at the Arnold Arboretum to a scientific report (Bartholomew et al., 1983), warm seed flats on the benches, there was and a listing of the germplasm brought back great anticipation among the staff who care- to the United States was prepared shortly after fully inspected the trays for germinating seed- the expedition had been completed (Dudley, lings. Not since the halcyon days of E. H. 1982, 1983). In addition, a catalogue was pub- Wilson earlier in this century had the green- lished (Hebb, 1982) of the excess plant house staff attempted to coax so many seeds material distributed through the American from China to germinate and grow in the New Association of Botanical Gardens and England climate. Arboreta in the spring of 1982. While it has It was in the spring of 1981 that the rich har- not been possible to trace the ultimate suc- vest of seeds collected by the Sino-American cess or failure of all of the living plants that Botanical Expedition to Western Hubei resulted from the expedition, it seems Province during the fall of 1980 began to ger- appropriate to focus briefly on the results of minate in the Arboretum’s greenhouses. Spe- this ongoing experiment, which has tested the cifically, the expedition spent six weeks hardiness of many Asian taxa in various local- during August and September of 1980 collect- ities and has allowed botanists and horticul- ing in the Shennongjia Forest District of turists both here and abroad to assess the northwestern Hubei Province, in a high, ornamental and landscape attributes of these mountainous region north of the Chang Jiang Chinese species. Included in these introduc- (Yangtze) River and on the border of Sichuan tions are some that represent the first of their Province. Additional collections were made in kind to be cultivated in western gardens. the Metasequoia region of southwestern The following summary features a few of Hubei Province during October of that year. the plants that now grow at the Arnold Many of the seedlings that resulted from these Arboretum. Over 450 accessions of seeds and collections were destined to enter the Arbore- other propagules collected by the expedition tum’s nurseries adjacent to the greenhouse were processed at the Dana Greenhouses, and complex and, ultimately, to join their North as of this writing 103 accessions have been American and other Asian cohorts on the incorporated into the living collections. At grounds of the Arnold Arboretum, where they first glance, this may seem like a low success have added significantly to the diversity of the rate, but a fair proportion of the collections Arboretum’s living collections. failed to germinate at all, and many of the 3 accessions that did germinate have proved not quently, the Arboretum’s collections will con- to be hardy. Finally, many of the slower- tinue to enlarge as additional material is growing accessions, such as the hollies and added in the future, and we can look forward rhododendrons, are still being grown in the to more new Chinese plants in our already Arboretum’s nurseries and will be planted out rich collections of woody Asian plants. in the collections in coming years. Conse- The ghost bramble, Rubus lasiostylus var. hubeiensis, in winter. Photo by R Del Tiedici. 4 The flowers of Sorbus yuana. Photo by Rdcz and Debreczy. Sorbus yuana Originally thought to represent Sorbus zahl- leading Chinese plant taxonomist and student bruckneri, this simple-leaved mountain ash of the genus Sorbus, who was a staunch sup- proved to represent a new species, which was porter of the 1980 Sino-American Expedition subsequently named Sorbus yuana Spong- and of continued cooperation between berg. The specific epithet, yuana, was given Chinese and American botanists. Sorbus to this species to honor Professor T. T. Yii, the yuana has thus far proven hardy in the Arnold 5 The fruits of Sorbus yuana. Photo by Rdcz and Debreczy. Arboretum, and trees in the living collections large, cherry-red, ovoid fruits in fall. Its beau- (AA #1539-80 and #1894-80) are approaching tiful dark green, alder-like leaves turn golden fifteen feet (4.5 meters) in height. Closely yellow in fall, and the species promises to be related to S. alnifolia, the celebrated Korean an outstanding ornamental tree. mountain ash, S. yuana produces large corymbs of pure white flowers in spring and 6 The author with Sorbus hemsleyi. Photo by 1. Racz. Sorbus hemsleyi More a botanical curiosity than a promising tury, this species was described as new by ornamental, Sorbus hemsleyi is another of the Camillo Schneider and also, somewhat later, simple-leaved mountain ashes collected by by Alfred Rehder as S. xanthoneura. It was not the 1980 Sino-American Expedition (AA realized, however, that the two species were #1771-80, #1878-80, and #1981-80). Originally one and the same until the collections of the discovered in Hubei Province by Augustine Sino-American Expedition were studied, and Henry toward the end of the nineteenth cen- the seeds brought back by the expedition con- 7 ~f The flowers of Sorbus hemsleyi. Photo by Rdcz and Debreczy. stitute its first introduction into western with a white tomentum on the lower surfaces. gardens and arboreta. Producing small As a consequence, the plants provide interest corymbs of pale green flowers in spring, which in the landscape, particularly when the leaves are followed by small clusters of greenish- are put in motion by a slight breeze. yellow fruits, S. hemsleyi is most notable for its bold, simple leaves. These are dark emer- ald green on the upper surfaces but covered 8 The leaves of Liquidambar acalycina. Photo by Rjcz and Debreczy. Liquidambar acalycina To my mind one of the most exciting new trict of southwestern Hubei Province. At the introductions of the 1980 Sino-American time of collection, we assumed that the tree Expedition is a plant that had only recently represented Liquidambar formosana, the been described as constituting a new species common and widely distributed Chinese by a Chinese taxonomist. We collected seeds sweetgum. But on close examination of the of this plant, Liquidambar acalycina, from a voucher herbarium specimens, it became venerable old tree growing by the roadside in apparent that our collection represented L. the fabled Metasequoia Valley in a remote dis- acalycina Chang, a species first described as 9 The habit of Liquidambar acalycina. Photo by Racz and Debreczy. recently as 1959. Ours was undoubtedly its cies, L. formosana. And unlike L. formosana, first introduction to western gardens, and in which-despite repeated attempts-has never the Arnold Arboretum a small grove of trees been hardy in the Boston area, L. acalycina grown from this seed lot (AA #1634-80) now has withstood winters outside in the Arnold occupies space close to the American sweet- Arboretum since 1984. gums. Ironically, this new Chinese species is more closely related to our American sweetgum than it is to the common Chinese spe- 10 Rhus chinensis in full bloom. Photo by Rdcz and Debreczy. Rhus chinensis Chinese sumac, Rhus chinensis, was first cul- the plants that resulted from the Sino- tivated in western gardens by Philip Miller in American Expedition constitute our only cur- the Chelsea Physic Garden in London during rent accession of this taxon from China. One the middle of the eighteenth century. And plant (AA #475-80-C) has become well estab- while we grow several accessions of this wide- lished along Meadow Road adjacent to the ranging Asian shrub at the Arnold Arboretum, Cotinus collection, where it has grown into The handsome foliage of Rhus chinensis. Photo by Rdcz and Debreczy. a large, multiple-stemmed shrub, already bees. Its compound leaves-each with a upwards of fifteen feet (4.5 meters) in height. winged rachis and seven to thirteen leaflets- In flower from late August into September, the add interest to the plants in the late summer ornamental value of this shrub centers on its landscape, and particularly in fall when they large panicles of creamy-white flowers, which turn a brilliant red. provide a rich source of nectar for foraging 12 Malus baccata Malus baccata, the so-called Siberian crab, Among the several species of crabapples col- and its occurrence in western Hubei Province lected in the Shennongjia Forest District in represents a considerable extension of its Hubei Province, a number were introduced by known range. Its unexpected occurrence far seed collections, and a group of these proved south of its usual range in northern Asia con- difficult to determine based only on their fused us when we attempted to identify it at fruiting voucher specimens. One collection in the time of collection, and we thought it particular (SABE #1298, now grown as AA might represent a new species. It was only #1843-80) represented a small tree that was through recourse to the flowering material particularly attractive in fruit, the small but from the plants grown in the Arboretum that abundantly produced, fire-engine red pomes its correct identity has been ascertained. As suspended on extremely long stalks. Plants can be seen in the accompanying photograph, from this gathering have now flowered in the the flowers, too, are produced on very long Arnold Arboretum, and by using both flower- pedicels, and en masse transform each limb ing and fruiting material, we have been able of the flowering tree into a beautiful bower of to determine the plant’s identity.

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