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38-408: The River Ash may refer to:- The River Ash tree ( Fraxinus pennsylvanica ). River Ash, Hertfordshire River Ash, Surrey Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title River Ash . If an internal link led you here, you may wish to change the link to point directly to

76-763: A zygote . The definition avoids reference to male and female reproductive structures, which are rare in fungi. An individual of a dioecious fungal species not only requires a partner for mating, but performs only one of the roles in nuclear transfer, as either the donor or the recipient. A monoecious fungal species can perform both roles, but may not be self-compatible. Dioecy has the demographic disadvantage compared with hermaphroditism that only about half of reproductive adults are able to produce offspring. Dioecious species must therefore have fitness advantages to compensate for this cost through increased survival, growth, or reproduction. Dioecy excludes self-fertilization and promotes allogamy (outcrossing), and thus tends to reduce

114-399: A critical food source, as the leaves that fall from the trees are particularly suitable for tadpoles to feed upon in ponds (both temporary and permanent), large puddles, and other water sources. Species such as red maple, which are taking the place of ash due to the ash borer, are much less suitable for the frogs as a food source — resulting in poor frog survival rates and small frog sizes. It

152-436: A frequency about half of that for the forward transition. In Silene , since there is no monoecy, it is suggested that dioecy evolved through gynodioecy. Very few dioecious fungi have been discovered. Monoecy and dioecy in fungi refer to the donor and recipient roles in mating, where a nucleus is transferred from one haploid hypha to another, and the two nuclei then present in the same cell merge by karyogamy to form

190-466: A harsh lesson learned, cities like Chicago did not replace dead elms with a 1:1 ash:elm ratio. Instead, Norway, silver, red and sugar maples, honey locust, linden/basswood, redbud, crabapples, and hackberry, among others, were also utilized during this recovery period and in new urban and suburban areas. Fortunately, with these additional species, many cities were able to reduce the percent of ash and other species to much lower levels (20% average) than during

228-485: A result of which the beetles had an enormous food supply to boost their population well above Infestation thresholds. The tree was also extensively propagated and sold by local nurseries. According to the American Nursery Industry, "Back in the late 1980s, Dr. Frank Santamour Jr., then a research geneticist with the U.S. National Arboretum, proposed the 10-20-30 formula for diversity in the urban forest, limiting

266-669: A slower rate, only affected one species, and did not kill the trees before they could attain reproductive maturity. Many areas have banned the sale of ash seedlings in nurseries, although seeds may be sold as they are not a vector for the insect. Green ash is also vulnerable to many other diseases including ash yellows , ash dieback and ash bacterial canker that can cause gradual loss of vigor and exhibit similar symptoms to emerald ash borer infestation such as crown dieback, bark cracking, and epicormal sprouts. These conditions are most common on stressed trees in areas of poor soil, urban pollution, and lack of moisture. A wave of ash dieback struck

304-455: A velvety texture. The leaves are 15–30 cm (6–12 in) long, oppositely arranged, pinnately compound with seven to nine (occasionally five or eleven) leaflets, these 5–15 cm (2–6 in) (rarely 18 cm or 7 in) long and 1.2–9 cm ( 1 ⁄ 2 – 3 + 9 ⁄ 16  in) broad, with serrated margins and short but distinct, downy petiolules a few millimeters long. They are green both above and below. The autumn color

342-788: Is called " dioecious " when each sporophyte plant has only one kind of spore-producing organ, all of whose spores give rise either to male gametophytes, which produce only male gametes (sperm), or to female gametophytes, which produce only female gametes (egg cells). For example, a single flowering plant sporophyte of a fully dioecious species like holly has either flowers with functional stamens producing pollen containing male gametes (staminate or 'male' flowers), or flowers with functional carpels producing female gametes (carpellate or 'female' flowers), but not both. (See Plant reproductive morphology for further details, including more complex cases, such as gynodioecy and androdioecy .) Slightly different terms, dioicous and monoicous , may be used for

380-482: Is currently being investigated with the hope that green ash could be restored using the surviving trees. Although larval infestation by the invasive emerald ash borer kills more 99% of green ash trees, it has been found that emerald ash borer infestation induces production of secoiridoids in infested trees and that cultivars that are progeny of "lingering ash" produce higher levels of these secoiridoids than progeny of susceptible trees. The spread of emerald ash borer

418-606: Is golden-yellow and depending on the climate, green ash's leaves may begin changing color the first week of September. The flowers are produced in spring at the same time as the new leaves, in compact panicles ; they are inconspicuous with no petals, and are wind-pollinated. The fruit is a samara 2.5–7.5 cm (1–3 in) long comprising a single seed 1.5–3 cm ( 5 ⁄ 8 – 1 + 1 ⁄ 8  in) long with an elongated apical wing 2–4 cm ( 3 ⁄ 4 – 1 + 1 ⁄ 2  in) long and 3–7 mm ( 1 ⁄ 8 – 9 ⁄ 32  in) broad. It

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456-451: Is killed readily when exposed to emerald ash borer, while the Asian species F. mandschurica shows resistance against emerald ash borer. The United States Forest Service has discovered small numbers of "lingering ash" trees in the wild that have remained healthy after emerald ash borer swept through the population. The possibility of these trees possessing genetic resistance to the beetle

494-454: Is more common in woody plants , and heterotrophic species. In most dioecious plants, whether male or female gametophytes are produced is determined genetically, but in some cases it can be determined by the environment, as in Arisaema species. Certain algae , such as some species of Polysiphonia , are dioecious. Dioecy is prevalent in the brown algae ( Phaeophyceae ) and may have been

532-407: Is often planted for shade or as a windbreak . For the last two centuries American elm and ash, which both belong to the ancient Elm-Ash-Cottonwood Bottomland ecosystem, achieved distinction as North America's two most popularly planted urban species, used primarily for their superior survival traits and slowly maturing 180–300 year majestic natural beauty. Today used as living national monuments,

570-512: Is similar in properties to white ash wood, and is marketed together as "white ash". The commercial supply is mostly in the South. It is very popular, used in making electric guitars because it can be somewhat lighter than white ash without sacrificing too much in tone. It has a bright sound with long sustain, plus the wood grain is aesthetically desirable to many guitar players. Gibson , Fender , Ibanez , Warwick , and many other luthiers use ash in

608-408: Is sometimes divided into two varieties , Fraxinus pennsylvanica var. pennsylvanica (red ash) and Fraxinus pennsylvanica var. lanceolata (Borkh.) Sarg. (syn. var. subintegerrima (Vahl) Fern.; green ash) on the basis of the hairless leaves with narrower leaflets of the latter, but the two intergrade completely, and the distinction is no longer upheld by most botanists. Like other species in

646-561: Is the lack of tannins in the American ash varieties that makes them good for the frogs as a food source and also not resistant to the ash borer. Varieties of ash from outside North America typically have much higher tannin levels and resist the borer. Maples and various non-native invasive trees, trees that are taking the place of American ash species in the North American ecosystem, typically have much higher leaf tannin levels. Green ash wood

684-547: Is threatened by the emerald ash borer , a beetle introduced from Asia . This introduced pest kills most ash trees that it infests, accounting for mass die-offs of ashes in North America and in Moscow, Russia. Asian ashes have a high tannin content in their leaves which makes them unpalatable to the beetle, while most American species (with the notable exception of blue ash ) do not. A common garden experiment showed that green ash

722-406: Is unlikely that mutations for male and female sterility occurred at the same time. In angiosperms unisexual flowers evolve from bisexual ones. Dioecy occurs in almost half of plant families, but only in a minority of genera, suggesting recent evolution. For 160 families that have dioecious species, dioecy is thought to have evolved more than 100 times. In the family Caricaceae , dioecy is likely

760-435: The gametophyte generation of non-vascular plants, although dioecious and monoecious are also used. A dioicous gametophyte either produces only male gametes (sperm) or produces only female gametes (egg cells). About 60% of liverworts are dioicous. Dioecy occurs in a wide variety of plant groups. Examples of dioecious plant species include ginkgos , willows , cannabis and African teak . As its specific name implies,

798-439: The gametophytes , which produce gametes. A male gamete and a female gamete then fuse to produce a new diploid sporophyte. In bryophytes ( mosses , liverworts and hornworts ), the gametophytes are fully independent plants. Seed plant gametophytes are dependent on the sporophyte and develop within the spores, a condition known as endospory . In flowering plants, the male gametophytes develop within pollen grains produced by

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836-703: The Dutch elm disease era where from 56% to 100% of the trees were elm. Injections and spraying of ashes with pesticides has been used in city parks to protect valued trees from emerald ash borer. Record cold temperatures during the winter of 2018–19 are estimated to have killed as much as 80% of ash borer larvae in the Upper Midwest. Both American elm and green ash were extremely popular due to rapid growth and tolerance of urban pollution and road salt, so many housing developments in Michigan were lined from end to end with ashes,

874-533: The National Park Service is protecting Thomas Jefferson 's 200-year-old planted example, and George Washington 's 250-year-old white ash which has a 600-year possible lifespan. Green ash had been widely used as a primary ornamental and long lived monument tree until the elm fad of the 1880s, and regained top position once again after Dutch elm disease arrived. Other continents learned of American ash species' urban survivability and unique beauty through

912-458: The ancestral sexual system. Dioecious flowering plants can evolve from monoecious ancestors that have flowers containing both functional stamens and functional carpels. Some authors argue monoecy and dioecy are related. In the genus Sagittaria , since there is a distribution of sexual systems, it has been postulated that dioecy evolved from monoecy through gynodioecy mainly from mutations that resulted in male sterility. However, since

950-568: The ancestral state in that group. In plants, dioecy has evolved independently multiple times either from hermaphroditic species or from monoecious species. A previously untested hypothesis is that this reduces inbreeding; dioecy has been shown to be associated with increased genetic diversity and greater protection against deleterious mutations. Regardless of the evolutionary pathway the intermediate states need to have fitness advantages compared to cosexual flowers in order to survive. Dioecy evolves due to male or female sterility, although it

988-597: The ancestral state is unclear, more work is needed to clarify the evolution of dioecy via monoecy. Dioecy usually evolves from hermaphroditism through gynodioecy but may also evolve through androdioecy , through distyly or through heterostyly . In the Asteraceae , dioecy may have evolved independently from hermaphroditism at least 5 or 9 times. The reverse transition, from dioecy back to hermaphroditism has also been observed, both in Asteraceae and in bryophytes, with

1026-730: The construction of their guitars. Dioecious In zoology, dioecy means that an animal is either male or female, in which case the synonym gonochory is more often used. For example, most animal species are gonochoric, almost all vertebrate species are gonochoric, and all bird and mammal species are gonochoric. Dioecy may also describe colonies within a species, such as the colonies of Siphonophorae (Portuguese man-of-war), which may be either dioecious or monoecious . Land plants ( embryophytes ) differ from animals in that their life cycle involves alternation of generations . In animals, typically an individual produces gametes of one kind, either sperm or egg cells . The gametes have half

1064-585: The expression of recessive deleterious mutations present in a population. In trees, compensation is realized mainly through increased seed production by females. This in turn is facilitated by a lower contribution of reproduction to population growth, which results in no demonstrable net costs of having males in the population compared to being hermaphroditic. Dioecy may also accelerate or retard lineage diversification in angiosperms . Dioecious lineages are more diversified in certain genera, but less in others. An analysis suggested that dioecy neither consistently places

1102-657: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=River_Ash&oldid=933089036 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Green Ash Fraxinus pennsylvanica , the green ash or red ash , is a species of ash native to eastern and central North America , from Nova Scotia west to southeastern Alberta and eastern Colorado , south to northern Florida , and southwest to Oklahoma and eastern Texas . It has spread and become naturalized in much of

1140-627: The northeastern United States in the 1950s–60s that killed an estimated 70% of ashes in the region. Green ash is one of the most widely planted ornamental trees throughout the United States and much of Canada but mostly Alberta , including in western areas where it is not native. It is also widely planted in Argentina . It is very popular due to its good form and resistance to disease. About 40% of boulevard trees in Edmonton, Alberta , are green ash. It

1178-476: The number of chromosomes of the individual producing them, so are haploid . Without further dividing, a sperm and an egg cell fuse to form a zygote that develops into a new individual. In land plants, by contrast, one generation – the sporophyte generation – consists of individuals that produce haploid spores rather than haploid gametes . Spores do not fuse, but germinate by dividing repeatedly by mitosis to give rise to haploid multicellular individuals,

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1216-657: The perennial stinging nettle Urtica dioica is dioecious, while the annual nettle Urtica urens is monoecious. Dioecious flora are predominant in tropical environments. About 65% of gymnosperm species are dioecious, but almost all conifers are monoecious. In gymnosperms, the sexual systems dioecy and monoecy are strongly correlated with the mode of pollen dispersal, monoecious species are predominantly wind dispersed ( anemophily ) and dioecious species animal-dispersed ( zoophily ). About 6 percent of flowering plant species are entirely dioecious and about 7% of angiosperm genera contain some dioecious species. Dioecy

1254-441: The plantings in a community to no more than 10 percent within a single species, 20 percent within a genus and 30 percent within a family." Many communities are using a more strict 5-10-20 rule today, because of the threat posed by emerald ash borer. The emerald ash borer proved to be a far worse and potentially more serious threat than epidemics of the past such as chestnut blight and Dutch elm disease because those diseases spread at

1292-494: The section Melioides , Fraxinus pennsylvanica is dioecious , with male and female flowers produced on separate individuals. It is the most widely distributed of all the American ashes; its range centers on the midwestern U.S. and Great Plains. Seedlings of the tree have a high tolerance to water logging which may explain why the natural habitat of green ash is almost exclusively stream sides and bottomlands. The large seed crops provide food to many kinds of wildlife. Green ash

1330-460: The sporophyte's stamens , and the female gametophytes develop within ovules produced by the sporophyte's carpels . The sporophyte generation of a seed plant is called " monoecious " when each sporophyte plant has both kinds of spore-producing organ but in separate flowers or cones. For example, a single flowering plant of a monoecious species has both functional stamens and carpels, in separate flowers. The sporophyte generation of seed plants

1368-488: The western United States and also in Argentina and Europe, from Spain to Russia . Other names more rarely used include downy ash, swamp ash, and water ash. Fraxinus pennsylvanica is a medium-sized deciduous tree reaching 12–25 metres (39–82 feet) (rarely to 45 m or 148 ft) tall with a trunk up to 60 centimetres (24 inches) in diameter. The bark is smooth and gray on young trees, becoming thick and fissured with age. The winter buds are reddish-brown, with

1406-551: The worldwide popularity of Midwestern Prairie style ecology and architectural movement. Modernizing cities in Russia and China then began using imported green ash a century ago to line streets and landscape new public parks. Advantages of green ash include its tolerance of harsh urban environmental conditions, ease of propagation, and (in eastern North America) its value for wildlife as a native keystone species . North American native ash tree species are used by North American frogs as

1444-532: Was facilitated by the extensive use of green ash as an ornamental tree in the central U.S. following the loss of American elms in the 1950s–60s due to Dutch elm disease . That epidemic was the result of a similar overuse of elms in urban environments, leading to a monoculture that lacked any disease or pest resistance. Scientifically for green ash this is because modern cultivars utilized regionally were parented from sometimes only four individual trees selected for unique traits and male seedless flowering. Proclaiming

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