''Quercus acerifolia'' (also called maple-leaf oak) is a rare North American species of

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

in the red oak section of ''Quercus'' (known as ''Lobatae''). The species was first described in 1927 from samples collected by E.J. Palmer in the

Ozark Mountains The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, and Oklahoma, as well as a small area in the southeastern corner of Kansas. The Ozarks cover ...

. The initial documentation classified the species as '' Quercus shumardii var. acerifolia.'' "Maple-leaf Oak". ''Arnold Arboretum''. Retrieved 2025-03-03. The species was first perceived as a variant of Shumard oak due to its similar foliage and ranges. Over two decades later, the tree was re-evaluated by botanists Nick Alan Stoynoff and William J. Hess, who determined that it was a distinct species. Their case for reclassification was presented in the paper, "A New Status for ''Quercus shumardii'' var. ''acerifolia'' (Fagaceae)," published in the journal ''Sida'' in 1990.Stoynoff, Nick; Hess, William J. (1990). "A New Status for Quercus Shumardii Var. Acerifolia (fagaceae)". ''SIDA, Contributions to Botany''. 14 (2): 267–271.

ISSN An International Standard Serial Number (ISSN) is an eight-digit to uniquely identify a periodical publication (periodical), such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs a ...

0036-1488. The reclassification was based on the tree's unique

ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

and morphological characteristics including leaf shape, acorn size, and

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

. The species was renamed ''Quercus acerifolia'', due to its leaf shape which resembles that of a maple tree.

Description

Foliage

Maple-leaf Oak is often mistaken as a variant of other oak species due to its similar leaf shape and general appearance, but its subtle morphological and genetic traits distinguish it from other oaks. The venation of the

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

shows them to be technically pinnately five-lobed but with the two middle lobes larger than the other three. This makes the leaves appear palmately lobed at first glance, similar to those of the

Norway maple ''Acer platanoides'', commonly known as the Norway maple, is a species of maple native to eastern and central Europe and western Asia, from Spain east to Russia, north to southern Scandinavia and southeast to northern Iran. It was introduced to ...

tree (''Acer platanoides)''."Quercus acerifolia: Wenzell, K., Kenny, L. & Beckman, E." ''IUCN Red List of Threatened Species''. 2015-03-10. Retrieved 2025-03-03. The leaves are broader and shorter than the typical ''Q. shumardii'' leaves. The epithet ''acerifolia'' means "maple-leaved." This medium-sized

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

tree has distinctive fall coloration, with its leaves transitioning from green to vibrant shades of red."Mapleleaf Oak – CornellBotanicGardens". ''cornellbotanicgardens.org''. Retrieved 2025-04-01.

Growth patterns

The tree sometimes reaches a height of 15 meters (50 feet). This species appears in both stemmed shrub and single trunk tree versions. Maple-leaf Oak produces insignificant yellowish-green flowers in spring with emerging foliage. This species of oak also produces acorns which are typically no more than seventeen mm long, about 1/3 smaller than ''Q. shumardii'' acorns. The tree bark is smoother when the tree is young, but pronounced dark ridging occurs as the tree ages.

Habitat and distribution

Maple-leaf Oak is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Ouachita Mountains The Ouachita Mountains (), simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thru ...

of the State of

Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...

. The geographic distribution of this species is remarkably limited. Its range covers just 24 square kilometers across locations including Sugarloaf Mountain, Magazine Mountain, Pryor Mountain, and Porter Mountain within the Ouachita Mountains (Fig. 1). This species grows primarily on

xeric Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (Ancient Greek 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this habita ...

sites, occupying high elevation

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

habitats with dry and rocky soils. This restricted distribution is a significant contributing factor to its endangerment status.

Ecology

The Maple-leaf Oak serves as a keystone species in its native ecosystems, contributing to many key ecological processes. Oak trees play a vital ecological role by contributing to

nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...

and

soil fertility Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.

, regulating

water cycle The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth across different reservoirs. The mass of water on Earth remains fai ...

s, providing habitats and food for wildlife, and sequestering carbon. The decomposition of large oak leaves provides a nutrient-rich substrate which improves soil quality and supports the

microbiota Microbiota are the range of microorganisms that may be commensal, mutualistic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found ...

communities. Oak trees also provide critical wildlife habitat in

temperate forest A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest terrestrial biome, covering 25% of the world's forest area, only behind the boreal forest, which covers about 3 ...

s, providing canopy shelter and nesting sites for birds and habitat for other mammals and fungi. Species of woodpeckeers, thrushes, and warblers rely on these oak trees for habitat and feed on caterpillars found on the trees during the breeding season (Fig. 2). The acorns produced by the tree also serve as a food source for a range of wildlife in the

Endangerment status and threats

The Maple-leaf Oak is listed as a critically endangered tree species in the Red List of US Oaks."Quercus grisea: Kenny, L., Wenzell, K., Beckman, E. & Jerome, D." ''IUCN Red List of Threatened Species''. 2017-01-24. Retrieved 2025-03-03. The Red list of US Oaks was developed to identify the oak species of highest extinction concern globally. This rating scale was determined using species characteristics including geographic range, rate of decline, fragmentation, and population size. This species is considered critically imperiled due to its highly fragmented population distribution and its small population size. Fewer than 600 individuals are present in the wild, making it extremely vulnerable to extinction pressures.''Subedi, Suresh C.; Ruston, Boone; Hogan, J. Aaron; Coggeshall, Mark V. (2023-09-05). "Defining the extent of suitable habitat for the endangered Maple-Leaf oak (Quercus acerifolia)". Frontiers of Biogeography. 15 (3). doi:10.21425/F5FBG58763.

1948-6596.'' Oak species such as the maple-leaf oak are at risk of extinction primarily due to climate change induced habitat shifts,

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...

and

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

. This species is threatened by

habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

throughout its fragmented range, largely attributed to anthropogenic activities such as logging and development in the

. Climate change induced range shifts also threaten the maple-leaf oak. Climate shifts throughout the world have resulted in protected habitat of endangered species becoming uninhabitable. As sessile organisms, trees often struggle to relocate establish themselves in new suitable habitat quickly enough before widespread mortality occurs. This relocation process that often results in high tree mortality. Other risk factors for this species are likely to be intensified by the impacts of climate change such as pest and pathogen pressures, drought, and fire. With a population of fewer than 600 individuals and its highly fragmented range, the maple-leaf oak is also highly susceptible to genetic bottlenecks. With fewer individuals, the genetic pool becomes smaller, increasing the likelihood of inbreeding. Under these circumstances,

inbreeding depression Inbreeding depression is the reduced biological fitness caused by loss of genetic diversity as a consequence of inbreeding, the breeding of individuals closely related genetically. This loss of genetic diversity results from small population siz ...

s can occur, where deleterious traits spread throughout the population and reduce fitness of the species as a whole.

Conservation

Challenges

Preserving the biodiversity of oak trees is particularly challenging due to seed type. Acorns produced by oak trees are not viable for

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ...

once they have been dried, meaning they cannot be preserved in seedbanks unlike many other tree species.Kramer, Andrea T.; Pence, Valerie (2001). "The Challenges of Ex Situ Conservation for Threatened Oaks" (PDF). ''International Oak Journal''. 23. This can make ''ex-situ'' conservation efforts more intensive and costly because all reforestation must be done with living specimens.

Current efforts

There are various conservation efforts for the Maple-leaf Oak, but they have had limited success. The four identified native subpopulations of the species are protected; these are Sugarloaf Mountains-Midland Peak Natural Area, Mount Magazine State Park, and the

Ouachita National Forest The Ouachita National Forest is a vast congressionally-designated United States National Forest, National Forest that lies in the western portion of Arkansas and portions of extreme-eastern Oklahoma, USA. History The Ouachita National Forest is ...

. There are also ''ex-situ'' conservation efforts in place at the

Cincinnati Zoo The Cincinnati Zoo & Botanical Garden is the second oldest zoo in the United States, founded in 1873 and officially opening in 1875. It is located in the Avondale neighborhood of Cincinnati, Ohio. It originally began with in the middle of the ...

, U.S. National Arboretum,

Morton Arboretum The Morton Arboretum, in Lisle, Illinois, United States, is a public garden and outdoor museum with a library, herbarium, and program in tree research including the Center for Tree Science. Its grounds, covering 1,700 acres (6.9 square kilometre ...

and

Missouri Botanical Garden The Missouri Botanical Garden is a botanical garden located at 4344 Shaw Boulevard in St. Louis, Missouri. It is also known informally as Shaw's Garden for founder and philanthropy, philanthropist Henry Shaw (philanthropist), Henry Shaw. I ...

. Groves of the tree are under cultivation in several locations, notably Stephens Lake Park Arboretum in

Columbia, Missouri Columbia is a city in Missouri, United States. It was founded in 1821 as the county seat of Boone County, Missouri, Boone County and had a population of 126,254 as recorded in the 2020 United States census, making it the List of cities in Misso ...

. Though the species range is extremely limited, new research has identified other suitable habitat for proposed recovery efforts. Recent ecological niche modeling has identified predicted suitable habitat for ''Q. acerifolia'' in 20 counties across Arkansas and Oklahoma. Bioclimatic and

topographic Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scienc ...

variables were among the most influential range predictors of the species. The results of this niche modeling have informed conservation and restoration efforts as to where ''Q. acerifolia'' can survive, providing a basis for new protected areas and human-assisted migration efforts. Genetic research is also fundamental to the conservation efforts of ''Q. acerifolia''. The Morton Arboretum Conservation Biology lab is conducting a detailed genetic study to assess the

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

within the species. In this study, 19 microsatellite regions, specific

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

sequences used as genetic markers, were identified and analyzed to compare the genetic diversity between 316 garden and 148 wild individuals. This study will determine how well the

of wild populations has been preserved in ''ex-situ'' populations and can influence collection strategies to uphold the species’ genetic integrity.

Future directions

Conservation efforts for endangered oak species are necessary to maintain biodiversity within the genus, and protect the many ecosystems that rely on the presence of oak species. Successful conservation efforts must involve establishing more protected areas, restoration projects, community awareness, and continued research.

References

External links

photo of herbarium specimen at Missouri Botanical Garden, collected in Arkansas in 1924
{{Taxonbar, from=Q3081804 acerifolia Flora of Arkansas Endemic flora of the United States Trees of Northern America Plants described in 1927 Endangered flora of the United States Taxonomy articles created by Polbot