| 0 | PI 635109 | 'Jefferson' | Ulmus americana L. | Maryland, United States | NC7 | | Not Available | 2004 | DEVELOPED | | | | | | Cultivar | Selected from approximately 600 elms planted on the National Mall in Washington D.C. Triploid selection released jointly by the U.S. National Arboretum and the National Park Service in 2004 because of its disease tolerance and exceptional horticultural characteristics. In experiments conducted in the District of Columbia and at Glenn Dale, Maryland, rooted cuttings have demonstrated high levels of tolerance to both species of the fungus which causes Dutch elm disease. Tolerance of this clone to Dutch elm disease is characterized by a significantly lower extent of foliar symptoms and crown dieback after fungal inoculation, compared to other American elm selections and seedlings. Although not completely immune to the disease, it has an unusually high level of disease tolerance and will contribute to the diversity of elm selections now becoming available in the nursery and landscape industries. A diversity of American elm cultivars will help sustain the species as it begins to regain its stature in the urban forest. Distinguished by dark green leaves which develop earlier in the spring and are retained later in the fall than surrounding American elms. The parent tree is approximately 70 years old (90 cm DBH, 20.6 m tall) and has an expansive umbrella-shaped crown. Branch unions are broad and U-shaped compared to the narrow V unions often found in other American elm trees. The bark is smooth, light to reddish gray in young trees becoming dark gray and fissured in older trees. Summer leaves average 106 mm long by 59 mm wide and are dark green, turning yellow in the autumn. In adaptability trials, it has grown well in the District of Columbia, Maryland, Minnesota, Missouri, New Jersey, Oklahoma, Oregon, and Tennessee, and can be considered adaptable from USDA Zones 4 through 7. Readily propagated by softwood cuttings. Using conventional techniques, 90% of the cuttings collected in mid-May in the District of Columbia usually root within 10 weeks. Excellent choice for planting in urban and suburban sites, large yards, and recreational and industrial parks. It will make a good street tree where there is a wide tree lawn, and where a high arching effect is desired. Its combination of Dutch elm disease tolerance, widespread adaptability, and umbrella-shaped crown will fill important needs of the American public. | 1662748 | PI 635109 |
| 1 | PI 590997 | 'Valley Forge' | Ulmus americana L. | District of Columbia, United States | NC7 |  | | 1995 | DEVELOPED | | | | | | Cultivar | Introduced by the U.S. National Arboretum in 1995. Tetraploid selected by A. M. Townsend and L. R. Schreiber. Unusually high levels of tolerance to both aggressive and non-aggressive strains of the fungus causing Dutch elm disease. Superior horticultural characteristics. Upright, arching, broad vase-shaped branching structure with full, dense canopy of leaves. Propagules off original parent tree (suspected origin is Nebraska) are 7.9 meters tall with average crown spread of 9.1 meters after 12 growing seasons. Summer leaves average 119 mm long x 74 mm wide and are green but gradually turn yellow in autumn. Bark divided into grayish, flat-topped ridges, separated by roughly diamond-shaped fissures, and is typical of the species. In adaptability trials, performed well in Ohio, Maryland, and the District of Columbia. Adaptable from USDA Zone 5 to 7. Easy to propagate. Excellent for planting in urban and suburban sites, large yards, and recreational and industrial parks. Good street trees where there is wide tree lawn, and where high arching effect is desired. | 1493695 | PI 590997 |
| 2 | PI 590998 | 'New Harmony' | Ulmus americana L. | District of Columbia, United States | NC7 | | Not Available | 1995 | DEVELOPED | | | | | | Cultivar | Introduced by the U.S. National Arboretum in 1995. Tetraploid selected by A. M. Townsend and L. R. Schreiber. Unusually high levels of disease tolerance to both aggressive and non-aggressive strains of the fungus causing Dutch elm disease. Superior horticultural characteristics. Broadly, vase-shaped crown, with main trunk dividing about 9 meters from the ground into several erect limbs which strongly arch above and which terminate in numerous slender, often drooping branchlets. Parent tree (origin near Springfield, Ohio) is 20.7 meters tall, with an average crown spread of 21.9 meters. Leaves average 107 mm long and 63 mm wide, and turn yellow in autumn. Bark is typical of species. Grows well in Georgia, Maryland, Minnesota, New Jersey, Ohio, Oklahoma, Pennsylvania, and Tennessee. Adaptable from USDA Zone 5 to 7, with possible cold hardiness into Zone 4. Easy to propagate. Excellent for planting in urban and suburban sites, large yards, and recreational and industrial parks. Good street trees where there is wide tree lawn, and where high arching effect is desired. | 1493745 | PI 590998 |
| 3 | PI 536050 | 'Prospector' | Ulmus davidiana Planch. var. japonica (Sarg. ex Rehder) Nakai | District of Columbia, United States | NC7 | | | 1989 | DONATED | 11/07/1989 | | | | | Cultivar | Introduced by the U.S. National Arboretum, originally selected by A.M. Townsend and L.R. Schrieber in 1975 from a 1965 planting of U. wilsoniana seedlings in Delaware, Ohio. High level of resistance in both laboratory and field trials to Dutch elm disease (Ceratocystis ulmi) and elm leaf beetle (Xanthogaleruca luteola). Plant 7.0 m tall with crown spread of 6.4 m at 9 years old. Crown vase-shaped, becoming pendulous at a lower height than American elm. Young leaves orange red (35A), maturing to yellow green (144A) to green (137B). Autumn leaf color yellow (13A). Branch angle average 53 deg. Reliably adaptable to USDA zones 4-7. Excellent street, lawn, highway, or park tree. Heat, drought, and cold tolerant. | 1430986 | PI 536050 |
| 4 | PI 313550 | 'Christine Buisman' | Ulmus minor Mill. | Netherlands | NC7 | | | 1966 | COLLECTED | | | | | | Cultivar | Tree uniform, very erect, medium leafy, much branched. Excellent winter hardiness and spring vigor. | 1234072 | PI 313550 |
| 5 | PI 138018 | 386-J | Ulmus macrocarpa Hance | Beijing Shi, China | | | Historic | 1940 | COLLECTED | | Hsieh Chu Yuan Garden, Peiping | | | | | | 1860384 | PI 138018 |
| 6 | Ames 33357 | JDC/UT/2016/018/733 | Ulmus thomasii Sarg. | Iowa, United States | NC7 |  | | 2016 | COLLECTED | 06/03/2016 | Malanaphy Springs State Preserve just northwest of Decorah, T99N R8W SW ¼ NW ¼ SE ¼ Sec. 31 | 43.34713800, -91.83840000 | 302 | Deciduous woods. Rocky substrate. 20 degree northwest-facing slope | Wild material | Ulmus thomasii (Rock elm) is an underutilized tree species both in conservation and in the urban landscape. Charles Sprague Sargent (first director of the Arnold Arboretum of Harvard University, Boston, MA) described the wood of Rock Elm as "heavy, hard, very strong and tough, closely grained, and susceptible of receiving a beautiful polish". Historically noted for a variety of uses in woodworking including furniture, heavy agricultural implements, timber frame buildings, pianos, hockey sticks, and hand tools. U. thomasii is extremely drought tolerant, adaptable to very calcareous soils, and compared to U. americana or U. rubra has a very conservative growth rate requiring minimal attention in regards to pruning. Rock elm naturally tends to develop into a nice structural specimen in the landscape, unlike other fast growing U. americana cultivars in the nursery trade needing frequent attention. Rock elm has very fissured bark and is well known for maintaining a strong central leader resulting in a very attractive, pyramidal form. Despite many literature sources stating that "wings" on the stems are a key identifiying characteristic, this trait is not reliable and many genotypes may completely lack "wings" on the stems. While growth habit and morphology of dormant buds (very pointy) are good traits to help aid in identification, fruits are the best way to confirm identity. Fruits are densly pubescent, often described as "inflated" and generally reach maturity a couple weeks after U. rubra and U. americana. U. thomasii flowering in central Iowa typically occurs the last week in April into the first week in May and are rather distinguishable from other Ulmus in being pendulous. Fruits are extremely prized treats for many birds, where fruits are often "robbed" prior to full maturity. Fruits are also highly prized by many other animals such as mice, squirrels, chipmunks, turkeys, etc. and are generally consumed within hours after fruit abscission. The native range of U. thomasii is concentrated in the northeastern United States and into Canada with disjunct populations documented in northwestern Missouri and northwestern Arkansas (Little, E. L. Jr. 1971). In the 1895 Silva of North America (vol. 7) it was stated that, “The value of the wood of the Rock Elm threatens its extinction and most of the large trees have already been cut.” Today, since rock elm is rather rare, especially in areas near the edges of its range, many states list the species as endangered or threatened warranting preservation efforts. This accession represents genetics from northeast Iowa (Winneshiek County). In an assessment of some of the largest Ulmus thomasii (native and cultivated) across Iowa, four of the nine largest specimens in Iowa are present in Malanaphy Springs State Preserve where this accession was sampled. The second largest U. thomasii in the state located in Malanaphy Springs was measured on 22 May 2020 with a circumference of 6.42', height of 86.58', and an average crown spread of 68.00' (180 points) (Rouw, M., personal communication, 8 February 2021). | 1940580 | Ames 33357 |
| 7 | NA 77501 | NA 77501 | Ulmus serotina Sarg. | Tennessee, United States | NA | | Not Available | 2008 | COLLECTED | 10/04/2005 | Cheekwood Botanical Gardens; native trees in woodland near house. | | | | | | 1951446 | NA 77501 |
| 8 | NA 76690 | NA 76690 | Ulmus crassifolia Nutt. | Louisiana, United States | NA | | Not Available | 2006 | COLLECTED | 10/2005 | Tensas River Wildlife Management Area, off Hwy. 4, along entry road. | | | | Wild material | | 1895871 | NA 76690 |
| 9 | NA 76216 | 44-95 | Ulmus castaneifolia Hemsl. | | NA | | Not Available | 2005 | | | | | | | Wild material | | 2115940 | NA 76216 |
| 10 | NA 76222 | NA 76222 | Ulmus chenmoui W. C. Cheng | | NA | | Not Available | 2005 | | | | | | | | | 1951842 | NA 76222 |
| 11 | NA 76223 | 181-84 | Ulmus sp. | | NA | | Not Available | 2005 | | | | | | | Cultivated material | Reidentified as Ulmus sp. based on examination of 76223-001 by Alan Whittemore; Alan's note: "morphology wrong for U. davidiana; need fruit for identification" | 2115962 | NA 76223 |
| 12 | NA 76224 | NA 76224 | Ulmus davidiana Planch. | | NA | | Not Available | 2005 | | | | | | | | | 1950760 | NA 76224 |
| 13 | NA 76230 | NA 76230 | Ulmus macrocarpa Hance | | NA | | Not Available | 2005 | | | | | | | | | 1952759 | NA 76230 |
| 14 | NA 76234 | NA 76234 | Ulmus davidiana Planch. var. japonica (Sarg. ex Rehder) Nakai | | NA | | Not Available | 2005 | | | | | | | Wild material | | 1951024 | NA 76234 |
| 15 | NA 76235 | NA 76235 | Ulmus szechuanica W. P. Fang | | NA | | Not Available | 2005 | | | | | | | Wild material | | 1951095 | NA 76235 |
| 16 | NA 76239 | NA 76239 | Ulmus castaneifolia Hemsl. | | NA | | Not Available | 2005 | | | | | | | Cultivated material | Possibly Morton Arboretum's 46-95 | 2115958 | NA 76239 |
| 17 | NA 76240 | NA 76240 | Ulmus sp. | | NA | | Not Available | 2005 | | | | | | | | | 1951911 | NA 76240 |
| 18 | NA 76241 | NA 76241 | Ulmus prunifolia W. C. Cheng & L. K. Fu | | NA | | Not Available | 2005 | | | | | | | | | 2113623 | NA 76241 |
| 19 | NA 76243 | NA 76243 | Ulmus castaneifolia Hemsl. | | NA | | Not Available | 2005 | | | | | | | Wild material | Received as Ulmus glaucescens. ID verified by Alan Whittemore - SBL. [Actually, of the data from Alan's herbarium specimens prepared from plants of this accession contradicts this earlier (likely 2013, the last time this record was updated) statement. Two plants, 76243-001 and 76243-003, were reidentified as U. castaneifolia. Another plant, 76243-002, was reidentified by Alan as U. davidiana var. japonica. Based on that, this accession will be reidentified as U. castaneifolia, and the 76243-002 will be assigned a new accession number, NA 86811. -SBL] Supposed to have had wild origin, but no collection locality was provided, not even a province--China is all that is known for certain. | 2113624 | NA 76243 |
| 20 | NA 76247 | GW 04-246-01 | Ulmus microcarpa L. K. Fu | | NA | | Not Available | 2005 | | | | | | | | | 2115948 | NA 76247 |
| 21 | NA 76248 | aff. U. davidiana | Ulmus davidiana Planch. | | NA | | Not Available | 2005 | | | | | | | Cultivated material | tentative ID per A. Whittemore | 2115957 | NA 76248 |
| 22 | NA 76250 | NA 76250 | Ulmus szechuanica W. P. Fang | | NA | | Not Available | 2005 | | | | | | | | | 1953489 | NA 76250 |
| 23 | NA 76255 | NA 76255 | Ulmus harbinensis S. Q. Nie & G. Q. Huang | | NA | | Not Available | 2005 | | | | | | | | | 1952807 | NA 76255 |
| 24 | WLP 1935 | GE-2004-108 | Zelkova carpinifolia (Pall.) K. Koch | Georgia | NA | | | 2004 | COLLECTED | 10/05/2004 | Imereti: Ajameti | 42.16318000, 42.74020000 | 110 | | Uncertain improvement status | | 1777542 | WLP 1935 |
| 25 | NA 73233 | NA 73233 | Ulmus rubra Muhl. | North Carolina, United States | NA | | Not Available | 2003 | COLLECTED | | Chimney Rock State Park. | | | | Wild material | | 1951161 | NA 73233 |
| 26 | NA 68915 | NA 68915 | Ulmus macrocarpa Hance | | NA | | Not Available | 1997 | | | | | | | | | 1952049 | NA 68915 |
| 27 | NA 64945 | WD178 | Zelkova schneideriana Hand.-Mazz. | Hubei Sheng, China | NA | | Not Available | 1994 | COLLECTED | 10/01/1994 | | | | | Wild material | | 1777036 | NA 64945 |
| 28 | NA 44933 | J-157-78 | Zelkova serrata (Thunb.) Makino | Honshu, Japan | NA | | Not Available | 1978 | COLLECTED | 10/17/1978 | Honshu, Ishikawa Prefecture, Saru-yama | | | Sunny trail. | Wild material | | 1776295 | NA 44933 |