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A birch is a thin-leaved deciduous hardwood tree of the genus Betula, in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus Betula contains 30 to 60 known taxa of which 11 are on the IUCN 2011 Red List of Threatened Species. They are a typically rather short-lived pioneer species widespread in the Northern Hemisphere, particularly in northern areas of temperate climates and in boreal climates.
Betula pendula, commonly known as silver birch, warty birch, European white birch, or East Asian white birch, is a species of tree in the family Betulaceae, native to Europe and parts of Asia, though in southern Europe, it is only found at higher altitudes. Its range extends into Siberia, China, and southwest Asia in the mountains of northern Turkey, the Caucasus, and northern Iran. It has been introduced into North America, where it is known as the European white birch, and is considered invasive in some states in the United States and parts of Canada. The tree can also be found in more temperate regions of Australia.
Betula pubescens, commonly known as downy birch and also as moor birch, white birch, European white birch or hairy birch, is a species of deciduous tree, native and abundant throughout northern Europe and northern Asia, growing farther north than any other broadleaf tree. It is closely related to, and often confused with, the silver birch, but grows in wetter places with heavier soils and poorer drainage; smaller trees can also be confused with the dwarf birch.
White birch is a common name for Betula papyrifera, a species of tree native to northern North America.
The Field Elm cultivar Ulmus minor 'Viminalis Marginata', a variegated form of Ulmus minor 'Viminalis', was first listed as Ulmus campestris var. viminalis marginataHort. by Kirchner in 1864. Both Van Houtte and Späth marketed an U. campestris viminalis marginata in the late 19th century.
The elm cultivar Ulmus 'Crispa Aurea' was first mentioned by Schelle & Beissner in 1903, as Ulmus montana crispa aurea.
The Wych Elm cultivar Ulmus glabra 'Latifolia Aurea' was listed by Schelle in Beissner et al. Handbuch der Laubholz-Benennung 84. 1903, but without description.
The European White Elm cultivar Ulmus laevis 'Aureovariegata', a yellow-variegated form, may have been the tree first listed, without description, in Hortus Regius Monacensis (1829) as Ulmus effusa variegata, grown at the Munich Botanic Garden. An Ulmus effusa fol. variegatis (Hort.) was first described c.1890 by the Späth nursery of Berlin, which distributed the tree in the late 19th century. The name U. effusa f. aureovariegata appeared in Beissner and Schelle's Handbuch der Laubholz-Benennung, 1903, without description.
The European White Elm cultivar Ulmus laevis 'Punctata' was mentioned in 1873, 1889, and later in 1903 as U. effusa f. punctata, but without description.
The elm cultivar Ulmus 'Nemoralis' was listed by Schelle in Beissner et al. (1903), as U. campestris f. nemoralisHort. Considered "possibly U. carpinifolia " by Green.
Weeping trees are characterized by soft, limp twigs. This characterization may lead to a bent crown and pendulous branches that can cascade to the ground. While weepyness occurs in nature, most weeping trees are cultivars. Because of their shape, weeping trees are popular in landscaping; generally they need a lot of space and are solitary so that their effect is more pronounced. There are over a hundred different types of weeping trees. Some trees, such as the cherry, have a variety of weeping cultivars. There are currently around 550 weeping cultivars in 75 different genera, although many have now disappeared from cultivation.
Ulmus × hollandica 'Wentworthii Pendula', commonly known as the Wentworth Elm or Wentworth Weeping Elm, is a cultivar with a distinctive weeping habit that appears to have been introduced to cultivation towards the end of the 19th century. The tree is not mentioned in either Elwes and Henry's or Bean's classic works on British trees. The earliest known references are Dutch and German, the first by de Vos in Handboek tot de praktische kennis der voornaamste boomen (1890). At about the same time, the tree was offered for sale by the Späth nursery of Berlin as Ulmus Wentworthi pendulaHort.. The 'Hort.' in Späth's 1890 catalogue, without his customary label "new", confirms that the tree was by then in nurseries as a horticultural elm. De Vos, writing in 1889, states that the Supplement to Volume 1 includes entries announced since the main volume in 1887, putting the date of introduction between 1887 and 1889.
Fraxinus angustifolia 'Pendula Vera', or true weeping narrow-leafed ash, is a weeping tree and a cultivar of Fraxinus angustifolia subsp. angustifolia, the Narrow-leafed Ash. It was first mentioned by Beissner, Schelle & Zabel in 1903. No trees are known to survive of this cultivar.
Euceraphis punctipennis, the downy birch aphid or European birch aphid, is a species of aphid in the order Hemiptera. These aphids are tiny green insects with soft bodies and membranous wings. They are found living on downy birch trees where they feed and multiply on the buds and leaves by sucking sap.
Birch dieback is a disease of birch trees that causes the branches in the crown to die off. The disease may eventually kill the tree. In an event in the Eastern United States and Canada in the 1930s and 1940s, no causal agent was found, but the wood-boring beetle, the bronze birch borer, was implicated in the severe damage and death of the tree that often followed. In similar crown dieback occurrences in Europe several decades later, the pathogenic fungus Melanconium betulinum were found in association with affected trees, as well as Anisogramma virgultorum and Marssonina betulae.
The Field Elm cultivar Ulmus minor 'Cucullata Variegata', a variegated form of U. minor 'Cucullata', was listed by C. de Vos, in 1867, as U. americana cucullata folia variegata and by Schelle in Beissner Handbuch der Laubholz-Benennung, 82 (1903) as U. campestris concavifolia cucullata variegataHort, without description.
Taphrina betulina is a fungal plant pathogen that causes the gall, witches broom, which is a chemical infection of birch buds or the developing shoots, leading to a proliferation of growth. It was first described by Emil Rostrup in 1883 and is found in Europe, New Zealand and North America.
Acalitus calycophthirus is an eriophyid mite which causes big bud galls on birch twigs. It is found in Europe and was first described by the Austrian zoologist, Alfred Nalepa in 1891.
References
- ↑ Beissner, L., Schelle, E. & Zabel, H. (1903). Handbuch der Laubgehöl-Benennung: 625pp. Parey, Berlin.
- 1 2 Govaerts, R., Michielsen, K. & Jablonski, E. (2011). Untraced Weeping Broadleaf cultivars: an overview. Belgische Dendrologie Belge Archived March 22, 2012, at the Wayback Machine 2009: 19-30.
