Presentation on theme: "Elm trees first made an appearance in the Miocene period, about 40 million years ago. Originating in central Asia, the tree has flourished and has established."— Presentation transcript:
Elm trees first made an appearance in the Miocene period, about 40 million years ago. Originating in central Asia, the tree has flourished and has established itself over most of North America, Europe and Asia. Elms are deciduous and semi-deciduous trees comprising the genus Ulmus. The plant family is the Ulmaceae.
Dozens of elm species are found in the temperate and tropical-montane regions of North America and Eurasia, ranging southward into Indonesia. Elms are components of many kinds of natural forests. During the 19th and early 20th centuries, many species and cultivars of elms were planted as ornamental street, lawn, and park trees in Europe, North America, and parts of the Southern Hemisphere, notably Australasia
Dutch elm disease DED is caused by a micro-fungus transmitted by two species of Scolytus elm-bark beetle which act as vectors. The disease affects all species of elm native to North America and Europe, but many Asiatic species have evolved anti-fungal genes and are resistant. Fungal spores, Elm yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts. Elm yellows, also known as elm phloem necrosis, is very aggressive, with no known cure. Elm yellows occurs in the eastern United States and southern Ontario in Canada. It is caused by phytoplasmas which infect the phloem (inner bark) of the tree. Infection and death of the phloem effectively girdles the tree and stops the flow of water and nutrients. The disease affects both wild-growing and cultivated trees. A Diseased Tree
The first, less aggressive strain of the disease fungus, Ophiostoma ulmi, arrived in Europe from the Far East in 1910, and was accidentally introduced to North America in 1928, but was steadily weakened by viruses and had all but disappeared in Europe by the 1940s. The second, far more virulent strain of the disease Ophiostoma novo-ulmi was identified in Europe in the late 1960s, and within a decade had killed over 20 million trees (approximately 75%) in the UK alone. Approximately three times more deadly, the origin of the new strain remains a mystery.
The mucilaginous inner bark of the Slippery Elm Ulmus rubra has long been used as a demulcent, and is still produced commercially for this purpose in the United States with approval for sale as a nutritional supplement by the U.S. Food and Drug Administration. Sometimes slippery elm leaves are dried and ground into a powder, then made into a tea. Both slippery elm gruel and tea may help to soothe the digestive tract. Slippery elm may decrease the absorption of prescription medications.
Fodder Elms also have a long history of cultivation for fodder, with the leafy branches cut to feed livestock. The practice continues today in the Himalaya, where it contributes to serious deforestation Biomass As fossil fuel resources diminish, increasing attention is being paid to trees as sources of energy. In Italy, the Istituto per la Protezione delle Piante is (2012) in the process of releasing to commerce very fast growing elm cultivars, able to increase in height by > 2 m (6 ft) per annum. Food Elm bark, cut into strips and boiled, sustained much of the rural population of Norway during the great famine of 1812. The seeds are particularly nutritious, comprising 45% crude protein, and < 7% fibre by dry mass.
Familiar species The more abundant or better-known species of Ulmus include: Ulmus americana—American Elm, White Elm Ulmus davidiana—David Elm, Father David's Elm Ulmus davidiana var. japonica—Japanese Elm, Wilson's Elm Ulmus glabra—Wych Elm, Scots Elm Ulmus laevis—European White Elm, Fluttering Elm, Spreading Elm, (USA) Russian Elm Ulmus minor—Field Elm Ulmus parvifolia—Chinese Elm, Lacebark Elm Ulmus procera—English Elm, Atinian Elm Ulmus pumila—Siberian Elm Ulmus rubra—Slippery Elm, Red Elm Ulmus alata—Winged Elm, Wahoo Chinese Elm bonsai ELM – Different Species