Robinia pseudoacacia - Wikipedia. Robinia pseudoacacia, commonly known in its native territory as black locust,[1] is a medium- sized deciduoustree native to the southeastern United States, but it has been widely planted and naturalized elsewhere in temperate North America, Europe, Southern Africa[2] and Asia and is considered an invasive species in some areas.[3] Another common name is false acacia,[4] a literal translation of the specific name (pseudo meaning fake or false and acacia referring to the genus of plants with the same name.) It was introduced into Britain in 1. History and naming[edit]The name 'locust' is said to have been given to Robinia by Jesuit missionaries, who fancied that this was the tree that supported St. John in the wilderness, but it is native only to North America. The locust tree of Spain (Ceratonia siliqua or carob tree), which is also native to Syria and the entire Mediterranean basin, is supposed to be the true locust of the New Testament. Robinia is now a North American genus, but traces of it are found in the Eocene and Miocene rocks of Europe.[6]Distribution and invasive habit[edit]The black locust is native to the eastern United States, but the exact native range is not accurately known[7] as the tree has been cultivated and is currently found across the continent, in all the lower 4. Canada, and British Columbia.[1] The native range is thought to be two separate populations, one centered about the Appalachian Mountains, from Pennsylvania to northern Georgia, and a second westward focused around the Ozark Plateau and Ouachita Mountains of Arkansas, Oklahoma and Missouri. Black locust's current range has been expanded by humans distributing the tree for landscaping and now includes Pakistan, Australia, Canada, China, Europe, India, Northern and South Africa, temperate regions in Asia, New Zealand, Southern South America.[8]Black locust is an interesting example of how one plant can be considered an invasive species even on the same continent it is native to. Robinia pseudoacacia, commonly known in its native territory as black locust, is a medium-sized deciduous tree native to the southeastern United States, but it has. Australian Agronomy Conference. 1980 1st AAC. Contributed Papers. Surface Management Of Arable Soils. Tillage Components Of Conservation Cropping In The South Burnett. For example, within the western United States, New England region, and in the Midwest, black locust is considered an invasive species. In the prairie and savanna regions of the Midwest black locust can dominate and shade open habitats.[9] These ecosystems have been decreasing in size and black locust is contributing to this, when black locust invades an area it will convert the grassland ecosystem into a forested ecosystem where the grasses are displaced.[1. Black locust has been listed as invasive in Connecticut and Wisconsin, and prohibited in Massachusetts.[1]In Australia black locust has become naturalized within Victoria, New South Wales, South, and Western Australia. It is considered an environmental weed there.[8] In South Africa, it is regarded as a weed because of its habit suckering.[1. Description[edit]Black locust reaches a typical height of 4. Exceptionally, it may grow up to 5. It is a very upright tree with a straight trunk and narrow crown which grows scraggly with age.[5] The dark blue- green compound leaves with a contrasting lighter underside give this tree a beautiful appearance in the wind and contribute to its grace. Black locust is a shade intolerant species[7] and therefore is typical of young woodlands and disturbed areas where sunlight is plentiful and the soil is dry. In this sense, black locust can often grow as a weed tree. It also often spreads by underground shoots or suckers which contribute to the weedy character of this species.[5] Young trees are often spiny, however, mature trees often lack spines. In the early summer black locust flowers; the flowers are large and appear in large, intensely fragrant (reminiscent of orange blossoms), clusters. The leaflets fold together in wet weather and at night (nyctinasty) as some change of position at night is a habit of the entire leguminous family. Although similar in general appearance to the honey locust, it lacks that tree's characteristic long branched thorns on the trunk, instead having the pairs of short prickles at the base of each leaf; the leaflets are also much broader then honey locust. It may also resemble Styphnolobium japonicum which has smaller flower spikes and lacks spines. Detailed description[edit]. One black locust leaf showing 1. The bark is dark gray brown and tinged with red or orange in the grooves. It is deeply furrowed into grooves and ridges which run up and down the trunk and often cross and form diamond shapes.[5]The roots of black locust contain nodules which allow it to fix nitrogen as is common within the pea family. The branches are typically zig- zagy and may have ridges and grooves or may be round.[5] When young, they are at first coated with white silvery down, this soon disappears and they become pale green and afterward reddish or greenish brown. Prickles may or may not be present on young trees, root suckers, and branches near the ground; typically, branches high above the ground rarely contain prickles. R. pseudoacacia is quite variable in the quantity and amount of prickles present as some trees are densely prickly and other trees have no prickles at all. The prickles typically remain on the tree until the young thin bark to which they are attached is replaced by the thicker mature bark. They develop from stipules[1. They range from . Their color is of a dark purple and they adhere only to the bark.[1. Wood: Pale yellowish brown; heavy, hard, strong, close- grained and very durable in contact with the ground. The wood has a specific gravity of 0. The leaves are compound, meaning that each leaf contains many smaller leaf like structures called leaflets, the leaflets are roughly paired on either side of the stem which runs through the leaf (rachis) and there is typically one leaflet at the tip of the leaf (odd pinnate). The leaves are alternately arranged on the stem. Each leaf is 6–1. The leaflets are rounded or slightly indented at the tip and typically rounded at the base. The leaves come out of the bud folded in half, yellow green, covered with silvery down which soon disappears. Each leaflet initially has a minute stipel, which quickly falls, and is connected to the (rachis) by a short stem or petiolule. The leaves are attached to the branch with slender hairy petioles which is grooved and swollen at the base. The stipules are linear, downy, membranous at first and occasionally develop into prickles. The leaves appear relatively late in spring. The leaf color of the fully grown leaves is a dull dark green above and paler beneath. In the fall the leaves turn a clear pale yellow. The flowers open in May or June for 7–1. They are arranged in loose drooping clumps (racemes) which are typically 4–8 inches (1.
The flowers themselves are cream- white (rarely pink or purple) with a pale yellow blotch in the center and imperfectly papilionaceous in shape. They are about 1 inch (2. Each flower is perfect, having both stamens and a pistil (male and female parts). There are 1. 0 stamens enclosed within the petals; these are fused together in a diadelphous configuration, where the filaments of 9 are all joined to form a tube and one stamen is separate and above the joined stamens. The single ovary is superior and contains several ovules. Below each flower is a calyx which looks like leafy tube between the flower and the stem. It is made from fused sepals and is dark green and may be blotched with red. The pedicels (stems which connect the flower to the branch) are slender, . The fruit is a typical legume fruit, being a flat and smooth pea- like pod 2–4 inches (5. The fruit usually contains 4- 8 seeds.[5] The seeds are dark orange brown with irregular markings. They ripen late in autumn and hang on the branches until early spring.[6] There are typically 2. Winter buds: Minute, naked (having no scales covering them), three or four together, protected in a depression by a scale- like covering lined on the inner surface with a thick coat of tomentum and opening in early spring. When the buds are forming they are covered by the swollen base of the petiole. Cotyledons are oval in shape and fleshy. Reproduction and dispersal[edit]Black locust produces both sexually via flowers, and asexually via root suckers. The flowers are pollinated by insects, primarily by Hymenopteran insects. The physical construction of the flower separates the male and female parts so that self- pollination will not typically occur.[1. The seedlings grow rapidly but they have a thick seed coat which means that not all seeds will germinate. The seed coat can be weakened via hot water, sulfuric acid, or be mechanically scarified and this will allow a greater quantity of the seeds to grow.[5][1. The seeds are produced in good crops every year or every- other year. Root suckers are an important method of local reproduction of this tree. The roots may grow suckers after damage (by being hit with a lawn mower or otherwise damaged) or after no damage at all. The suckers are stems which grow from the roots, directly into the air and may grow into full trees. The main trunk also has the capability to grow sprouts and will do so after being cut down.[1. This makes removal of black locust difficult as the suckers need to be continually removed from both the trunk and roots or the tree will regrow. This is considered an asexual form or reproduction. The suckers allow black locust to grow into colonies which often exclude other species. These colonies may form dense thickets which shade out competition.[1. Black locust has been found to have either 2n=2. Human mediated dispersal[edit]Black locust has been spread and used as a plant for erosion control as it is fast growing and generally a tough tree.[1. The wood, considered the most durable wood in America, has been very desirable and motivated people to move the tree to areas where it is not native so the wood can be farmed and used. Ecology[edit]Robinia pseudoacacia seeds. Pruning Mistakes and How to Avoid Them. Simply cutting branches off of trees and shrubs will not necessarily give the desired effect. Doing it the wrong way may result in unsightly cut ends showing for a long time, heavy production of water sprouts producing an unbalanced look, oversized scars, etc. When removing branches, always make the final cut at the top of a branch collar (the swollen area where the branch meets the main stem) or at a node (where leaves or lateral branches generate from the branch you are cutting). Conifers take a long time to regenerate new growth when cut beyond the growing tips. Hard cutbacks should be avoided if possible, but when necessary these cuts should be made where the cut will be carefully hidden within surrounding foliage. Large, heavy branches should be slightly undercut before removing to prevent the bark from tearing when the wood breaks midway through cutting.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
March 2018
Categories |