Aesculus

The genus ''Aesculus'' ( or ), with notable species including buckeye and horse chestnut, comprises 13–19 species of flowering plants in the family Sapindaceae. They are trees and shrubs native to the temperate Northern Hemisphere, with six species native to North America and seven to 13 species native to Eurasia. Several hybrids occur. ''Aesculus'' exhibits a classical Arcto-Tertiary distribution.

Mexican buckeye seedpods resemble the ''Aesculus'' seedpods, but belong to a different genus.

Carl Linnaeus named the genus ''Aesculus'' after the Roman name for an edible acorn. Common names for these trees include "buckeye" and "horse chestnut", though they are not in the same order as the true chestnuts, '' Castanea'' in the Fagales. Some are also called white chestnut or red chestnut. In Britain, they are sometimes called conker trees because of their link to the game of conkers, played with the seeds, which are also called conkers.

Description

''Aesculus'' species have stout shoots with resinous, often sticky, buds, with opposite, palmately divided leaves, often very large—to across in the Japanese horse chestnut, ''A. turbinata''. Species are deciduous or evergreen. Flowers are showy, insect- or bird-pollinated, with four or five petals fused into a lobed corolla tube, arranged in a panicle inflorescence. Flowering starts after 80–110 growing degree days. The fruit matures to a capsule diameter, usually globose, containing one to three seeds (often erroneously called a nut) per capsule. Capsules containing more than one seed result in flatness on one side of the seeds. 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, while other capsules are warty or smooth. At maturity, the capsule splits into three sections to release the seeds.

''Aesculus'' seeds were traditionally eaten, after leaching, by the Jōmon people of Japan over about four millennia, until 300 AD.

All parts of the buckeye or horse chestnut tree are moderately toxic, including the nut-like seeds. The toxin affects the gastrointestinal system, causing gastrointestinal disturbances. The USDA notes that the toxicity is due to saponin aescin and glucoside aesculin, with alkaloids possibly contributing.

Native Americans used to crush the seeds and the resulting mash was thrown into still or sluggish waterbodies to stun or kill fish. They then boiled and drained (leached) the fish at least three times to dilute the toxin's effects. New shoots from the seeds also have been known to kill grazing cattle.

The genus was considered to be in the ditypic family Hippocastanaceae along with '' Billia'', but phylogenetic analyses of morphological and molecular data have more recently caused this family, along with the Aceraceae (maples and ''Dipteronia''), to be included in the soapberry family (Sapindaceae).

Selected species

The species of ''Aesculus'' include:

Cultivation

The most familiar member of the genus worldwide is the common horse chestnut, ''Aesculus hippocastanum''. 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 is the bottlebrush buckeye, ''Aesculus parviflora'', a 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 ''Aesculus'' × ''carnea'', a hybrid between ''A. hippocastanum'' and ''A. pavia''.

In art

Interpretations of the tree leaves can be seen in architectural details in the Reims Cathedral.

In history

The horse chestnut was not native to Britain and was only introduced from Europe in 1650 (on the estates of both Dawyck House and Stobo Castle).Scottish Garden Buildings by Tim Buxbaum p.11

The leaf of Aesculus was the official symbol of Kyiv on its coat of arms used from 1969 to 1995. It remains an official symbol of Kyiv to this day.

In the 1840 U.S. presidential campaign, candidate William Henry Harrison called himself the "log cabin and hard cider candidate", portraying himself sitting in a log cabin made of buckeye logs and drinking hard cider, causing Ohio to become known as "the Buckeye State".

In Geneva, Switzerland, an official chestnut tree is used to indicate the beginning of the Spring; every year since 1818, the tree is observed by the secretary of the Grand Council of Geneva (the local parliament), and the opening of the first leaf is recorded and announced publicly. Over the years, four different horse chestnut trees have been used for these recordings.

In North America, several native American tribes, particularly in the western and central United States, such as Miwok, Pomo, Yokut, Maidu, historically used Buckeye trees (''Aesculus spp.'') like California Buckeye to harvest fish by utilizing the saponins, which had been extracted by the plant's seeds. These tribes used crushed Buckeye nuts to release saponins into streams or shallow water, where the compounds would stun or kill the fish, allowing for easier capture.

See also

* Anne Frank tree

References

Explanatory notes

Citations

External links

Germplasm Resources Information Network: ''Aesculus''
* Forest, F., Drouin, J. N., Charest, R., Brouillet, L., & Bruneau A. (2001)
"A morphological phylogenetic analysis of Aesculus L. and Billia Peyr. (Sapindaceae)"
''Can. J. Bot.'' 79 (2): 154–169. .


King's American Dispensatory

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Sapindaceae genera
Taxa named by Carl Linnaeus