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44-455: Aesculus californica , commonly known as the California buckeye or California horse-chestnut, is a species of buckeye native to California and southwestern Oregon . Aesculus californica is a large deciduous shrub or small tree , up to 4–12 m (13–39 ft) tall, with gray bark often coated with lichens and mosses . It typically is multi-trunked, with a crown as broad as it

88-467: 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

132-572: 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

176-464: A rich nectar source for many species of butterflies, and squirrels and chipmunks consume the seeds. Hydroquinone and epicatechin have been isolated from the seeds and have been shown to have allelopathic properties by inhibiting plant growth. It is used as an ornamental plant for its striking leaf buds, lime green foliage, fragrant white flowers, red-brown foliage in mid to late summer, and architectural silver branches through fall. The tree also acts as

220-472: A soil binder, which prevents erosion in hilly regions. 'Aesculus' is Linnaeus ' name for horse chestnuts. It is derived from the old Roman name for a different species, Quercus petraea . 'Californica' means 'native to California '. Aesculus The genus Aesculus ( / ˈ ɛ s k j ʊ l ə s / or / ˈ aɪ s k j ʊ l ə s / ), with species called buckeye and horse chestnut , comprises 13–19 species of flowering plants in

264-548: Is a fig -shaped capsule 5–8 cm (2–3 in) long, containing a large, round, orange-brown seed , measuring 2–7 cm (0.8–2.8 in). The seeds are poisonous and are the largest known of any temperate (non-tropical) plant species. A. californica has adapted to its native Mediterranean climate by growing during the wet late winter and spring months and entering dormancy in the dry summer months, though those growing in coastal regions tend to hold on to their leaves until mid-autumn. The only Aesculus variety native to

308-510: Is another invasive plant species that may owe its success partly to allelopathy. Its success in North American temperate forests may be partly due to its excretion of glucosinolates like sinigrin that can interfere with mutualisms between native tree roots and their mycorrhizal fungi . Allelopathy has been shown to play a crucial role in forests, influencing the composition of the vegetation growth, and also provides an explanation for

352-579: Is high. Trees are long lived, with an estimated lifespan between 250–280 (300 maximum) years. The leaves are dark green, palmately compound with five (rarely seven) leaflets. Each leaflet is 6–17 cm (2.4–6.7 in) long, with a finely toothed margin and (particularly in spring) downy surfaces. The leaves are tender and prone to damage from both spring freezing or snow and summer heat and desiccation . The flowers are sweet-scented, white to pale pink, borne on erect panicles 15–20 cm (6–8 in) long and 5–8 cm (2–3 in) broad. The fruit

396-482: 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 . Interpretations of the tree leaves can be seen in architectural details in the Reims Cathedral . The horse chestnut

440-467: The Aceraceae ( maples and Dipteronia ), to be included in the soapberry family (Sapindaceae). The species of Aesculus include: 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

484-661: The Journal of Chemical Ecology that developed methods to separate the allelochemical effects from other competitive effects, using barley plants and inventing a process to examine the allelochemicals directly. In 1994, M.C. Nilsson at the Swedish University of Agricultural Sciences in Umeå showed in a field study that allelopathy exerted by Empetrum hermaphroditum reduced growth of Scots pine seedlings by ~ 40%, and that below-ground resource competition by E. hermaphroditum accounted for

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528-472: 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

572-431: The cytoplasm through oxidative damage ) has also been criticized, on the basis that (−)-catechin is actually an antioxidant. Many invasive plant species interfere with native plants through allelopathy. A famous case of purported allelopathy is in desert shrubs . One of the most widely known early examples was Salvia leucophylla , because it was on the cover of the journal Science in 1964. Bare zones around

616-512: The 1970s, great effort went into distinguishing competitive and allelopathic effects by some researchers, while in the 1990s others argued that the effects were often interdependent and could not readily be distinguished. However, by 1994, D. L. Liu and J. V. Lowett at the Department of Agronomy and Soil Science, University of New England in Armidale, New South Wales , Australia, wrote two papers in

660-687: The Austrian professor Hans Molisch in the book Der Einfluss einer Pflanze auf die andere - Allelopathie (The Effect of Plants on Each Other - Allelopathy) published in German. He used the term to describe biochemical interactions by means of which a plant inhibits the growth of neighbouring plants. In 1971, Whittaker and Feeny published a review in the journal Science , which proposed an expanded definition of allelochemical interactions that would incorporate all chemical interactions among organisms. In 1984, Elroy Leon Rice in his monograph on allelopathy enlarged

704-472: 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 2–5 cm (1–2 in) diameter, usually globose, containing one to three seeds (often erroneously called

748-660: 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 with the game of conkers , played with the seeds, also called conkers. Aesculus species have stout shoots with resinous, often sticky, buds, with opposite, palmately divided leaves, often very large—to 65 cm (26 in) across in

792-459: The Swiss botanist De Candolle suggested that crop plant exudates were responsible for an agriculture problem called soil sickness . Allelopathy is not universally accepted among ecologists. Many have argued that its effects cannot be distinguished from the exploitation competition that occurs when two (or more) organisms attempt to use the same limited resource, to the detriment of one or both. In

836-863: The West, A. californica is widely distributed in California, growing along the central coast and in the lower elevations of the Sierra Nevada and Cascade Range . Its range extends to the foothills of the Siskiyou Mountains in the Rogue Valley in Oregon. A small disjunct population is found in the Chino Hills near Chino, California . It is found growing in a wide range of conditions from crowded, moist, semi-shaded canyon bottoms to dry south-facing slopes and hilltops. In

880-436: The allelopathic interaction of the weeds Chromolaena odorata ( Eupatorium odoratum ) and Lantana camara on selected major crops. Many crop cultivars show strong allelopathic properties, of which rice ( Oryza sativa ) has been most studied. Rice allelopathy depends on variety and origin: Japonica rice is more allelopathic than Indica and Japonica-Indica hybrid. More recently, critical review on rice allelopathy and

924-676: The coastal ranges north of Big Sur it is found growing alone on slopes, or intermingled with valley oak ( Quercus lobata ), Oregon oak ( Q. garryana ), coast live oak ( Q. agrifolia ) and California bay laurel ( Umbellularia californica ). In the foothills of the Sierra Nevada, A. californica can be found standing alone in grassland at the lowest elevations, intermingled in blue oak woodlands at intermediate elevations, and in mixed evergreen forests of black oak ( Q. kelloggii ), gray pine ( Pinus sabiniana ), ponderosa pine ( P. ponderosa ) and interior live oak ( Q. wislizeni ) as it nears

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968-680: The compounds would stun or kill the fish, allowing for easier capture. Allelopathic Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities , and are also thought to be important in the success of many invasive plants . For specific examples, see black walnut ( Juglans nigra ) , tree of heaven ( Ailanthus altissima ), black crowberry ( Empetrum nigrum ), spotted knapweed ( Centaurea stoebe ), garlic mustard ( Alliaria petiolata ), Casuarina / Allocasuarina spp. , and nutsedge . It can often be difficult in practice to distinguish allelopathy from resource competition. While

1012-569: The definition to include all direct positive or negative effects of a plant on another plant or on micro-organisms by the liberation of biochemicals into the natural environment . Over the next ten years, the term was used by other researchers to describe broader chemical interactions between organisms, and by 1996 the International Allelopathy Society (IAS) defined allelopathy as "Any process involving secondary metabolites produced by plants, algae, bacteria and fungi that influences

1056-536: The discovery that (−)- catechin was purportedly responsible for the allelopathic effects of the invasive weed Centaurea stoebe was greeted with much fanfare after being published in Science in 2003. One scientist, Dr. Alastair Fitter , was quoted as saying that this study was "so convincing that it will 'now place allelopathy firmly back on center stage.'" However, many of the key papers associated with these findings were later retracted or majorly corrected, after it

1100-447: The existence of allelopathy, however many particular cases remain controversial. Furthermore, the specific modes of action of allelochemicals on different organisms are largely open to speculation and investigation. The term allelopathy from the Greek -derived compounds allilon - ( αλλήλων ) and - pathy ( πάθη ) (meaning "mutual harm" or "suffering"), was first used in 1937 by

1144-475: 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

1188-503: The former is caused by the addition of a harmful chemical agent to the environment, the latter is caused by the removal of essential resources (nutrients, light, water, etc.). Often, both mechanisms can act simultaneously. Moreover, some allelochemicals may function by reducing nutrient availability. Further confounding the issue, the production of allelochemicals can itself be affected by environmental factors such as nutrient availability, temperature and pH . Today, most ecologists recognize

1232-565: The germination rate of other plants by 50%. Current research is focused on the effects of weeds on crops, crops on weeds, and crops on crops. This research furthers the possibility of using allelochemicals as growth regulators and natural herbicides , to promote sustainable agriculture. Agricultural practices may be enhanced through the utilization of allelochemical producing plants. When used correctly, these plants can provide pesticide, herbicide, and antimicrobial qualities to crops. number of such allelochemicals are commercially available or in

1276-419: The growth and development of agriculture and biological systems." In more recent times, plant researchers have begun to switch back to the original definition of substances that are produced by one plant that inhibit another plant. Confusing the issue more, zoologists have borrowed the term to describe chemical interactions between invertebrates like corals and sponges . Long before the term allelopathy

1320-487: The growth of many plants. Spotted knapweed ( Centaurea ) is considered an invasive plant that also utilizes allelopathy. Another example of allelopathy is seen in Leucaena leucocephala , known as the miracle tree. This plant contains toxic amino acids that inhibit other plants’ growth but not its own species growth. Different crops react differently to these allelochemicals, so wheat yield decreases, while rice increases in

1364-556: The growth of these plants by about 50%. Capsaicin has been shown to deter both herbivores and certain parasites’ performance. Herbivores such as caterpillars show decreased development when fed a diet high in capsaicin. Allelochemicals are a useful tool in sustainable farming due to their ability to control weeds. The possible application of allelopathy in agriculture is the subject of much research. Using allelochemical producing plants in agriculture results in significant suppression of weeds and various pests. Some plants will even reduce

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1408-478: The limit of its range. Native American tribes, including the Pomo , Yokuts , and Luiseño , used the poisonous nuts and seeds to stupefy schools of fish in small streams to make them easier to catch. The bark, leaves, and fruits contain the neurotoxic glycoside aesculin , which causes hemolysis of red blood cells . Buckeye also makes a good fireboard for a bow drill or hand drill. Native groups occasionally used

1452-609: The patterns of forest regeneration. The black walnut (Juglans nigra) produces the allelochemical juglone , which affects some species greatly while others not at all. However, most of the evidence for allelopathic effects of juglone come from laboratory assays and it thus remains controversial to what extent juglone affects the growth of competitors under field conditions. The leaf litter and root exudates of some Eucalyptus species are allelopathic for certain soil microbes and plant species. The tree of heaven , Ailanthus altissima , produces allelochemicals in its roots that inhibit

1496-429: The plant as a food supply; after boiling and leaching the toxin out of the seeds or nut meats for several days, they could be ground into a flour or meal similar to that made from acorns. The nectar and pollen of the flowers is toxic to honeybees , so the trees should not be planted near apiaries. When the shoots are small and leaves are new, they are lower in toxins and are grazed by livestock and wildlife. The flowers are

1540-614: The possibility for weed management reported that allelopathic characteristics in rice are quantitatively inherited and several allelopathy-involved traits have been identified. The use of allelochemicals in agriculture provide for a more environmentally friendly approach to weed control, as they do not leave behind residues. Currently used pesticides and herbicides leak into waterways and result in unsafe water qualities. This problem could be eliminated or significantly reduced by using allelochemicals instead of harsh herbicides. The use of cover crops also results in less soil erosion and lessens

1584-448: The presence of L. leucocephala . Capsaicin is an allelochemical found in many peppers that are cultivated by humans as a spice/food source. It is considered an allelochemical because it is not required for plant growth and survival, but instead deters herbivores and prevents other plants from sprouting in its immediate vicinity. Among the plants it has been studied on are grasses, lettuce, and alfalfa, and on average, it will inhibit

1628-431: The process of large-scale manufacture. For example, leptospermone is an allelochemical in lemon bottlebrush ( Callistemon citrinus ). Although it was found to be too weak as a commercial herbicide, a chemical analog of it, mesotrione (tradename Callisto), was found to be effective. It is sold to control broadleaf weeds in corn but also seems to be an effective control for crabgrass in lawns . Sheeja (1993) reported

1672-536: The remaining growth reduction. For this work she inserted PVC-tubes into the ground to reduce below-ground competition or added charcoal to soil surface to reduce the impact of allelopathy, as well as a treatment combining the two methods. However, the use of activated carbon to make inferences about allelopathy has itself been criticized because of the potential for the charcoal to directly affect plant growth by altering nutrient availability. Some high profile work on allelopathy has been mired in controversy. For example,

1716-487: 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

1760-484: The shrubs were hypothesized to be caused by volatile terpenes emitted by the shrubs. However, like many allelopathy studies, it was based on artificial lab experiments and unwarranted extrapolations to natural ecosystems. In 1970, Science published a study where caging the shrubs to exclude rodents and birds allowed grass to grow in the bare zones. A detailed history of this story can be found in Halsey 2004. Garlic mustard

1804-489: 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

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1848-498: Was found that they contained fabricated data showing unnaturally high levels of catechin in soils surrounding C. stoebe . Subsequent studies from the original lab have not been able to replicate the results from these retracted studies, nor have most independent studies conducted in other laboratories. Thus, it is doubtful whether the levels of (−)-catechin found in soils are high enough to affect competition with neighboring plants. The proposed mechanism of action (acidification of

1892-452: Was not native to Britain and was only introduced from Europe in 1650 (on the estates of both Dawyck House and Stobo Castle ). 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

1936-412: Was used, people observed the negative effects that one plant could have on another. Theophrastus , who lived around 300 BC noticed the inhibitory effects of pigweed on alfalfa . In China around the first century CE , the author of Shennong Ben Cao Jing , a book on agriculture and medicinal plants, described 267 plants that had pesticidal abilities, including those with allelopathic effects. In 1832,

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