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Fraxinus pennsylvanica
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Fraxinus pennsylvanica
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 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 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 is golden-yellow and depending on the climate, green ash's leaves may begin changing color the first week of September in the northern parts of its native range.[where?] 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 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 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 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 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 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 than 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.
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Fraxinus pennsylvanica
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 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 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 is golden-yellow and depending on the climate, green ash's leaves may begin changing color the first week of September in the northern parts of its native range.[where?] 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 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 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 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 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 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 than 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.
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