Details for: Ames 36073, Ulmus thomasii Sarg., JDC/UT/2022/028/1009

Summary Data

Taxonomy:

Ulmus thomasii Sarg.

Top Name:

JDC/UT/2022/028/1009

Origin:

Collected – Iowa, United States

Maintained:

North Central Regional Plant Introduction Station

Received by NPGS:

05 Jun 2023

Improvement Status:

Wild material

Reproductive Uniformity:

Population

Form Received:

Seed

Life Cycle:

Perennial

Life Habit:

Tree

Backup Location:

National Laboratory for Genetic Resources Preservation

Availability

Form	Quantity	Note	Inventory	Cart
Seed	100 count	Sample represents seeds from a single mother tree. Seeds from additional mother trees may be provided upon request.	Ames 36073 23ncao01 SD

Images (19 total. Click on image for more.)

Core Passport Data

Taxonomy:

Ulmus thomasii Sarg.

Top Name:

JDC/UT/2022/028/1009

Origin:

Collected – Iowa, United States

Maintained:

North Central Regional Plant Introduction Station

Received by NPGS:

05 Jun 2023

Improvement Status:

Wild material

Reproductive Uniformity:

Population

Form Received:

Seed

Life Cycle:

Perennial

Life Habit:

Tree

Source History

Collected

05 June 2023.
Boone County, Iowa, United States
Locality: Ledges State Park approximately 4.75 miles south of Boone, T83N R26W (Madrid NW Quad.) near center of SE ¼ Sec. 16 and also NW ¼ SW ¼ Sec. 21.
Coordinates: 41.9978, -93.8797 (Map it)
Elevation: 288m.
Georeference protocol: Lat/lon determined by GPS
Habitat: Wild Habitat
Environment description: Moist deciduous woods typically on mid-slopes to base of slopes and also well-drained floodplains.
Number of plants sampled: 4
Associated species: Quercus rubra, Ostrya virginiana, Staphylea trifolia, Ulmus americana, Fraxinus nigra (dead or dying), Ulmus rubra (rare), Anemonella thalictroides, Podophyllum peltatum, Erythronium albidum, Cardamine sp., Claytonia virginica, Carpinus caroliniana, Celtis occidentalis, Carya cordiformis, Carya ovata, Tilia americana, Acer saccharum subsp. nigrum, Carex pensylvanica, Dicentra cucullaria, and Ribes missouriense.
Slope: 45
Comment: Specimens approximately sampled approximately 2-3 days past peak maturity. The largest specimen noted measured 21" DBH with a height of 75' 5" and a spread of 43' 5" (data captured on 4 May 2022 by M. Rouw). Sampled two areas separated by 0.97 miles with two trees sampled in each area separated by approximately 100 yards from each other. Coordinates provided represent sample #1. Coordinates for other trees sampled may be provided upon request. In terms of abundance, U. americana, U. thomasii, and U. rubra may be termed in abundance as common, infrequent, and rare, respectively.
Collector(s):

Donated

05 June 2023.
Iowa, United States

Donor(s):

Accession Names and Identifiers

JDC/UT/2022/028/1009

Type: Collector identifier

Carstens, Jeffrey D. USDA ARS NCRPIS

Ledges State Park

Type: Local name

Ames 36073

Type: Site identifier

Group: AMES

NC-7 Research Numbers

23ncao01 SD (2023)/Core sample #005(2024)

Type: Other or unclassified name

Single mother tree measuring 6.8" DBH and estimated at 40' in height.

Carstens, Jeffrey D. USDA ARS NCRPIS

23ncao02 SD (2023)/Core sample #007(2024)

Type: Other or unclassified name

Single mother tree measuring 21" DBH with a height of 75' 5" and a spread of 43' 5" (data captured on 4 May 2022 by M. Rouw).

Carstens, Jeffrey D. USDA ARS NCRPIS

23ncao04 SD (2023)/Core sample #001(2024)

Type: Other or unclassified name

Single mother tree measuring 7.0" DBH and estimated at 55' in height.

Carstens, Jeffrey D. USDA ARS NCRPIS

Narrative

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. Genetics of this accession would be representative of the species southwestern edge of its native range. Out of approximately 100 specimens noted throughout Ledges State Park only 1-2% of specimens had characteristic "wings" on the stems. Research was executed (Moore, P., 2024) involving the core sampling of U. thomasii and U. americana specimens in Ledges State Park to make growth ring widths and basal area increment comparisons. Results determined that the average age of cored trees U. thomasii (n=4) and U. americana (n=4) of both species was roughly 80 years, excluding the exceptional case of tree #007 (Ames 36073 23ncao02 SD). Tree #007 was aged at 300 years of age and currently (2025) ranks as the 14th largest U. thomasii in Iowa measuring 21" DBH with a height of 75' 5" and a spread of 43' 5" totalling 152.21 points (Rouw, M., personal communication, 4 May 2022). The computed mean density at 𝑀𝑀 = 12% for U. thomasii was 0.80 g/cm3, and for U. americana was 0.672 g/cm3. These values are both higher than the representative values inferred from the Woods Database which are 0.755 g/cm3 for U. thomasii and 0.56 g/cm3 for U. americana. To date, there is little to no information regarding U. thomasii resistance to Dutch Elm Disease. Collections of U. thomasii at the Arnold Arboretum have over-time succumbed to DED (Pruka, B., 2016). However, data recorded by Moore (2024) indicates that U. thomasii growing in central Iowa can surpass 300 years in age verifying it's long-term utilization in the landscape.

Ulmus thomasii Sarg.

Genus:

Ulmus

Subgenus:

Oreoptelea

Section:

Trichoptelea

Family:

Ulmaceae

Nomen number:

101705

Place of publication:

Silva 14:102. 1902 "thomasi"

Verified:

05/06/2009 by ARS Systematic Botanists.

Other conspecific taxa

Autonyms (not in current use), synonyms and invalid designations

Heterotypic Synonym(s)
Ulmus racemosa D. Thomas

Common names

Language	Name	seq	Citation
English	cork elm	1	Voss, E. 1972-. Michigan flora.
English	rock elm	1	Wiersema, J. H. & B. León. 1999. World economic plants: a standard reference CRC Press, Boca Raton, FL.
French	orme de Thomas	2	FNA Editorial Committee. 1993-. Flora of North America.
German	Felsenulme	2	Encke, F. et al. 1993. Zander: Handwörterbuch der Pflanzennamen, 14. Auflage
Swedish	klippalm	2	Aldén, B., S. Ryman, & M. Hjertson. 2012. Svensk Kulturväxtdatabas, SKUD (Swedish Cultivated and Utility Plants Database; online resource)

Annotations

Observations

Phenotype Data

Category	Descriptor	Description	Value	Sample Size	Study	Inventory	Availability
MORPHOLOGY	SEED LENGTH	Length of seed (samara) in milimeters, including the membranous wing.	17.9787	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao03 SD	Not Available
MORPHOLOGY	SEED LENGTH	Length of seed (samara) in milimeters, including the membranous wing.	18.5998	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao02 SD	Not Available
MORPHOLOGY	SEED LENGTH	Length of seed (samara) in milimeters, including the membranous wing.	19.1369	31	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao01 SD
MORPHOLOGY	SEED LENGTH	Length of seed (samara) in milimeters, including the membranous wing.	19.8744	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao04 SD	Not Available
MORPHOLOGY	SEED WIDTH	Width of seed (samara) in millimeters, including the membranous wing.	11.5776	31	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao01 SD
MORPHOLOGY	SEED WIDTH	Width of seed (samara) in millimeters, including the membranous wing.	12.3597	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao04 SD	Not Available
MORPHOLOGY	SEED WIDTH	Width of seed (samara) in millimeters, including the membranous wing.	13.1213	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao03 SD	Not Available
MORPHOLOGY	SEED WIDTH	Width of seed (samara) in millimeters, including the membranous wing.	13.5217	50	WOODY-ORNAMENTALS.ULMUS.SEEDS	Ames 36073 23ncao02 SD	Not Available