''Betula uber'', the Virginia round-leaf birch, is a rare species of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

in the birch family. One of the most

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of North American trees, it is

endemic Endemism is the state of a species being found 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 found elsew ...

Smyth County Smyth County is a county located in the U.S. state of Virginia. As of the 2020 census, the population was 29,800. Its county seat is Marion. History Smyth County was formed on February 23, 1832, from Washington and Wythe counties. The county ...

, in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

. It is part of the

temperate broadleaf and mixed forests Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These fo ...

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

Description

It is a moderately sized tree, growing up to 15 meters tall. The

crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...

is compact. The bark is aromatic and dark brown or black in color.Sharik,
''Betula uber'' Revised Recovery Plan.
USFWS. 1985. The leaf is round or slightly oval with a heart-shaped base and a toothed edge and measures up to 5 centimeters long. The

catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...

is up to 2.8 centimeters long and contains tiny samaras measuring 2 millimeters in length. The tree is

wind-pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...

and reproduces by

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

. Seed production is much heavier in some years than in others. The tree's lifespan is around 50 years.

Taxonomy

The tree was first described in 1914 as a variety of ''

Betula lenta ''Betula lenta'' (sweet birch, also known as black birch, cherry birch, mahogany birch, or spice birch) is a species of birch native to eastern North America, from southern Maine west to southernmost Ontario, and south in the Appalachian Mounta ...

'',Davis, E
Five-year Review: Virginia Roundleaf Birch.
USFWS. September 2006. and elevated to species status in 1945.Flora of North America
/ref> It hybridizes with ''B. lenta'' and it has been suggested that it is actually a round-leaved mutant form of ''B. lenta''. Some authorities prefer to treat it as a variety.

Conservation

After it was first discovered in 1914, the tree was not seen again and was thought to be

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

until 1975, when some individuals were found. These 18 adult trees and 23

sapling In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s and

seedling A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (embry ...

s were in a forest along the degraded banks of Cressy Creek on Smyth County, Virginia. The tree was federally listed as an

and

conservation Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws. Conservation may also refer to: Environment and natural resources * Nature conservation, the protection and managem ...

efforts were begun. Many seedlings were sprouted in

greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of Transparent ceramics, transparent material, such as glass, in which plants requiring regulated climatic condit ...

s and planted in the forest. By 1995 there were 20 populations and it was downlisted to threatened status. The tree was propagated in order to discourage collectors from taking wild specimens, or

vandals The Vandals were a Germanic peoples, Germanic people who first inhabited what is now southern Poland. They established Vandal Kingdom, Vandal kingdoms on the Iberian Peninsula, Mediterranean islands, and North Africa in the fifth century. The ...

from destroying them. A recent count estimated 961 individuals in the wild as of 2006. Eight of these are in the original creekside population.The Nature Conservancy
/ref> The species will not be removed from the

list yet because it has not been observed reproducing sexually, and naturally, more than once. The expansion of its range is limited because the area is surrounded by

agricultural land Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other organism, forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous ...

, but the territory on which the tree occurs is not immediately threatened.

References

External links

*
USDA Plants Profile
{{Taxonbar, from=Q1343018

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Flora of Virginia Endemic flora of the United States Flora of the Appalachian Mountains Trees of the Southeastern United States Smyth County, Virginia Critically endangered flora of the United States NatureServe critically imperiled species Taxonomy articles created by Polbot Plants described in 1918 Taxobox binomials not recognized by IUCN