Aesculus

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Aesculus

For the South African Thoroughbred racehorse see: Horse Chestnut (horse)
Horse Chestnut (horse)

Horse Chestnut is a champion thoroughbred racehorse bred in South Africa by Harry Frederick Oppenheimer at his Mauritzfontein Stud in Kimberley, Northern Cape....
.

The genus Aesculus, the buckeyes and Horse Chestnuts, comprises 13-19 species of woody tree

TREE

TREE was a Boston hardcore punk band formed in the summer of 1990. They were active in the Boston music scene until disbanding in 2002....
s and shrub

Shrub

A shrub or bush is a horticulture rather than strictly Botany category of woody plant, distinguished from a tree by its multiple stems and lower height, usually less than 5-6 m tall....
s native to the temperate northern hemisphere

Northern Hemisphere

The Northern Hemisphere is the half of a planet that is north of the equator?the word sphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator....
, with 6 species native to North America

North America

North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and almost totally in the western hemisphere....
and 7-13 species native to Eurasia

Eurasia

Eurasia is a large landmass covering about 53,990,000 km? or about 10.6% of the Earth's surface . Often considered a single continent, Eurasia comprises the traditional continents of Europe and Asia, concepts which date back to classical antiquity and the borders for which are somewhat arbitrary....
; there are also several hybrids. Species are deciduous or evergreen. This genus has traditionally been treated in the ditypic family Hippocastanaceae

Hippocastanaceae

Hippocastanaceae is the name given to a small group of trees and shrubs, when this group is treated as a familiy. Its most widespread genus is Aesculus ....
along with Billia, but recent phylogenetic analysis of morphological and molecular data has led to this family, along with the Aceraceae

Aceraceae

Aceraceae is a family of flowering plants also called the Maple Family. It contains two to four genera, depending upon the circumscription, of some 120 species of trees and shrubs....
(Maple

Maple

Acer is a genus of trees or shrubs commonly known as Maple. Maples are variously classified in a family of their own, the Aceraceae, or included in the family Sapindaceae....
s and Dipteronia

Dipteronia

Dipteronia is a genus of two living and one extinct species, regarded in the soapberry family Sapindaceae sensu lato after Angiosperm Phylogeny Group and more recently )or traditionally by several authors in Aceraceae, related to the maples....
), being included in the soapberry family (Sapindaceae
Sapindaceae

Sapindaceae, also known as the soapberry family, is a family of flowering plants in the order Sapindales. There are about 140-150 genera with 1400-2000 species, including maple, Aesculus and lychee....
).

The North American species are known as buckeyes and the Eurasian species as Horse Chestnuts. Some are also called white chestnut or red chestnut (as in some of the Bach flower remedies
Bach flower remedies

Bach flower remedies are dilutions of flower material developed by Edward Bach, an English physician and homeopath, in the 1930s. The remedies are used primarily for emotional and spiritual conditions, including but not limited to clinical depression, anxiety, insomnia and stress ....
). In Britain, they are sometimes called conker trees because of their link with the game of conkers, played with the seeds, also called conkers.

Etymology

The name Horse Chestnut is also often given as "horse chestnut" or "horsechestnut". One species very popular in cultivation, the Common Horse Chestnut Aesculus hippocastanum is also often known as just "Horse Chestnut". Linnaeus named the genus Aesculus after the Roman name for an edible acorn. The use of the term "horse" refers to their strength or inedibility, and does not here refer to their fitness as fodder for horses, except in folk etymology. The name buckeye derives from the resemblance of the seed to the brown eye of a buck (male deer
Deer

Deer are the ruminant mammals forming the family Cervidae . A number of broadly similar animals from related families within the order even-toed ungulate are often also called deer....
), and Horse Chestnut from the external resemblance of the seed to a chestnut, but being inedible. The buckeye blooms in summer and the Horse Chestnut in late spring.

Description
Aesculus are woody plant
Woody plant

A woody plant is a Vascular tissue plant that has a Perennial plant Plant stem that is above ground and covered by a layer of thickened bark. Woody plants are adapted to survive from one year to the next; the stem supports continued vegetative growth above ground from one year to next....
s from 4 to 36m tall (depending on species), and have stout shoots with resinous, often sticky, buds; opposite, palmately divided leaves, often very large (to 65 cm across in the Japanese Horse Chestnut Aesculus turbinata). Flowers showy, insect-pollinated, with four or five petal
Petal

A petal is one member or part of the Corolla of a flower. The corolla is the name for all of the petals of a flower; the inner perianth whorl, term used when this is not the same in appearance as the outermost whorl and is used to attract pollinators based on its advertising coloration....
s fused into a lobed corolla tube, arranged in a panicle inflorescence. Flowering starts after 80–110 growing degree day
Growing degree day

Growing degree days are a heuristic tool in phenology. GDD are used by horticulture and gardeners to predict the date that a flower will bloom or a crop reach maturity....
s. The fruit matures to a capsule 2–5 cm diameter, usually globose with 1-3 seeds (often erroneously called nuts) per capsule, more than 2 results in seeds being flat on one side; the point of attachment of the seed in the capsule (hilum) shows as a large circular whitish scar. The capsule epidermis has "spines" (botanically: prickles) in some species, other capsules are warty or smooth; capsule splits into three sections to release the seeds.

Cultivation

The most familiar member of the genus worldwide is the Common Horse Chestnut Aesculus hippocastanum, native to a small area of the Balkans
Balkans

The Balkans is the historical name of a geographic subregion of southeastern Europe. The region takes its name from the Balkan Mountains, which run through the centre of Bulgaria into eastern Serbia....
in southeast Europe
Europe

Europe is, conventionally, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural , the Caspian Sea, and by the Caucasus Mountains to the southeast....
, but widely cultivated throughout the temperate world. The yellow buckeye Aesculus flava (syn. A. octandra) is also a valuable ornamental tree with yellow flowers, but is less widely planted. Among the smaller species, the bottlebrush buckeye Aesculus parviflora also makes a very interesting and unusual flowering shrub. Several other members of the genus are used as ornamentals, and several horticultural hybrids have also been developed, most notably the red Horse Chestnut A. × carnea, a hybrid between A. hippocastanum and A. pavia.

They are generally fairly problem-free, though a recently discovered leaf-mining moth
Moth

A moth is an insect closely related to the butterfly, both being of the Order Lepidoptera. The differences between butterflies and moths are more than just taxonomy....
Cameraria ohridella is currently causing major problems in much of Europe, causing premature leaf fall which looks very unattractive. The symptoms (brown blotches on the leaves) can be confused with damage caused by the leaf fungus Guignardia aesculi, which is also very common but usually less serious. Common Horse Chestnut is also used as a food plant by the sycamore
Sycamore (moth)

The sycamore is a moth of the family Noctuidae. It is distributed through most of Europe.The forewings of this species are pale to dark grey with rather indistinct markings apart from a thin black basal streak....
, another species of moth.

Another disease in parts of North West Europe and North America is bleeding canker.

Uses
The nuts contain high concentrations of a saponin
Saponin

Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species....
-class toxin called aesculin
Aesculin

Aesculin is a glucoside that naturally occurs in the Horse-chestnut , California Buckeye and in daphnin ....
, which is toxic to many animals including humans because it causes hemolysis
Hemolysis

Hemolysis ?from the Greek Hemo-, Greek language meaning blood, -lysis, meaning to break open?is the breaking open of red blood cells and the release of hemoglobin into the surrounding fluid ....
(destruction of red blood cell
Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood....
s). The saponin can be eliminated by leaching the pulverized nuts in multiple changes of boiling water, to yield a wholesome starch
Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
y porridge
Porridge

Porridge, or porage, is a simple dish made by boiling oats or another cereal in water, milk, or both. It is eaten in a flat bowl or a dish....
once important to some Native American
Indigenous peoples of the Americas

The indigenous peoples of the Americas are the pre-Columbian inhabitants of the Americas, their descendants, and many ethnic groups who identify with those peoples....
peoples. Some animals, notably deer
Deer

Deer are the ruminant mammals forming the family Cervidae . A number of broadly similar animals from related families within the order even-toed ungulate are often also called deer....
and squirrel
Squirrel

File:Eichh?rnchen D?sseldorf Hofgarten edit.jpgA squirrel is one of many small or medium-sized rodents in the family Sciuridae. In the English language-speaking world, squirrel commonly refers to members of this family's genus Sciurus and Tamiasciurus, which are tree squirrels with large bushy tails, indigenous to Asia, the America...
s, are resistant to the toxins and can eat the nuts directly. An interesting side-note is that aesculin is a natural pH indicator
PH indicator

A pH indicator is a halochromism chemical chemical compound that is added in small amounts to a solution so that the pH of the solution can be determined easily....
which, when extracted turns from colorless to fluorescent blue under UV light in an acidic pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
range.

California buckeye Aesculus californica

Aesculus californica

Aesculus californica is a species of Aesculus endemic to California, and the only buckeye native to the state.It is a large shrub or small tree growing to 4-12 m tall, with gray bark often coated with lichens or mosses....
is known to cause poisoning of honeybees from toxic nectar (native bee
Bee

Bees are flying insects closely related to wasps and ants. Bees are a monophyly lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila....
species not being affected). Other buckeye species are thought to have the same effect, but the toxins are diluted because the trees are not usually abundant enough in any one area.

The wood is very pale whitish-brown, fairly soft and little-used. Uses include cheap furniture, boxes and firewood.

In Britain
United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
and Ireland
Ireland

Ireland is the List of islands by area in Europe, and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islet....
the game of conkers remains a common childhood pastime.

In some cultures, the buckeye tree is thought to bring good luck.

The Mexican buckeye
Mexican Buckeye

Ungnadia speciosa, the Mexican Buckeye, is a shrub or small tree native to northeastern Mexico and adjacent western Texas and southern New Mexico in the USA....
is related to Aesculus, but is in a separate genus, Ungnadia.

Extractives of the seeds have been shown to be useful for the treatment of chronic venous insufficiency.

Gallery

External links

Forest, F., Drouin, J. N., Charest, R., Brouillet, L., & Bruneau A. (2001). A morphological phylogenetic analysis of Aesculus L. and Billia Peyr. (Sapindaceae). Canad. J. Botany 79 (2): 154-169. .
King's American Dispensatory