''Quercus ellipsoidalis'', the northern pin oak or Hill's oak, is a 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 ...

tree native to the north-central

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and south-central

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

, primarily in the

Great Lakes region The Great Lakes region of Northern America is a binational Canadian– American region centered on the Great Lakes that includes the U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin and the Ca ...

and the Upper Mississippi Valley. It most commonly occurs on dry, sandy soils.

Description

''Quercus ellipsoidalis'' is a 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 growing to tall with an open, rounded crown. 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, ...

are glossy green, long and broad, lobed, with five or seven lobes, and deep sinuses between the lobes. Each lobe has 3–7 bristle-tipped teeth. The leaf is nearly hairless, except for small tufts of pale orange-brown down where the lobe veins join the central vein. The

acorn The acorn is the nut (fruit), nut of the oaks and their close relatives (genera ''Quercus'', ''Notholithocarpus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), en ...

s tend to be ellipsoid (

ellipse In mathematics, an ellipse is a plane curve surrounding two focus (geometry), focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special ty ...

-shaped, from which its scientific name derives), though they tend to be highly variable and range to globose, long and broad, a third to a half covered in a deep cup, green maturing pale brown about 18 months after

pollination Pollination is the transfer of pollen from an anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or bu ...

; the kernel is very bitter. The inner surface of the acorn cap is glabrous (hairless) to sparsely or moderately pubescent, and the hairs if present tend to be kinky rather than straight.

Taxonomy

Although the common name suggests a resemblance to the pin oak (''Q. palustris''), ''Q. ellipsoidalis'' has traditionally been thought to be closely related to the scarlet oak (''Q. coccinea''), and was in fact included in that species by many botanists. Recent work suggests that there is more gene flow between Hill's oak and black oak (''Q. velutina''), but the phylogenetic position of these species is still uncertain. The morphological similarity between ''Q. ellipsoidalis'' and ''Q. coccinea'' remains a source of confusion, especially in northwestern Indiana and southern Cook County, Illinois.Hipp AL, JA Weber (2008) Systematic Botany 33: 148-158
/ref>

Uses

Northern pin oak is planted as an

ornamental tree Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

, popular for its bright red fall color and tolerance of infertile sandy soils. The wood is used for fence posts, fuel and general construction. The cultivar 'Hemelrijk' has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...

References

External links

* *
Photo of herbarium specimen at Missouri Botanical Garden, collected in Illinois in 1899
{{Taxonbar, from=Q241698 ellipsoidalis Trees of Northern America Plants described in 1899 Least concern plants Least concern flora of North America Least concern flora of the United States