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Cannabis () is a flowering plant that includes three species (and seven taxa) or sub-species,〔(【引用サイトリンク】title=Cannabis sativa information from NPGS/GRIN )〕 ''sativa'', ''indica'', and ''ruderalis''. The plant is indigenous to Central Asia and the Indian Subcontinent. Cannabis has long been used for hemp fibre, for hemp oils, for medicinal purposes, and as a recreational drug. Industrial hemp products are made from cannabis plants selected to produce an abundance of fiber. To satisfy the UN Narcotics Convention, some cannabis strains have been bred to produce minimal levels of tetrahydrocannabinol (THC), the principal psychoactive constituent. Many plants have been selectively bred to produce a maximum of THC (cannabinoids) which is obtained by curing the flowers. Various compounds of the plant, including hashish and hash oil, are extracted from the plant.〔Erowid. 2006. (Cannabis Basics ). Retrieved on 25 February 2007〕 Globally, in 2013, 60,400 kilograms of cannabis were produced legally. In 2013 between 128 and 232 million people are thought to have used cannabis as a recreational drug (2.7% to 4.9% of the global population between the ages of 15 and 65). ==Description== Cannabis is an annual, dioecious, flowering herb. The leaves are palmately compound or digitate, with serrate leaflets.〔(【引用サイトリンク】title=Leaf Terminology (Part 1) )〕 The first pair of leaves usually have a single leaflet, the number gradually increasing up to a maximum of about thirteen leaflets per leaf (usually seven or nine), depending on variety and growing conditions. At the top of a flowering plant, this number again diminishes to a single leaflet per leaf. The lower leaf pairs usually occur in an opposite leaf arrangement and the upper leaf pairs in an alternate arrangement on the main stem of a mature plant. The leaves have a peculiar and diagnostic venation pattern that enables persons poorly familiar with the plant to distinguish a cannabis leaf from unrelated species that have confusingly similar leaves (see illustration). As is common in serrated leaves, each serration has a central vein extending to its tip. However, the serration vein originates from lower down the central vein of the leaflet, typically opposite to the position of, not the first notch down, but the next notch. This means that on its way from the midrib of the leaflet to the point of the serration, the vein serving the tip of the serration passes close by the intervening notch. Sometimes the vein will actually pass tangent to the notch, but often it will pass by at a small distance, and when that happens a spur vein (occasionally a pair of such spur veins) branches off and joins the leaf margin at the deepest point of the notch. This venation pattern varies slightly among varieties, but in general it enables one to tell ''Cannabis'' leaves from superficially similar leaves without difficulty and without special equipment. Tiny samples of ''Cannabis'' plants also can be identified with precision by microscopic examination of leaf cells and similar features, but that requires special expertise and equipment.〔Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: ''The Medicinal and Poisonous Plants of Southern and Eastern Africa'' 2nd ed Pub. E & S Livingstone 1962〕 The plant is believed to have originated in the mountainous regions northwest of the Himalayas. It is also known as hemp, although this term is often used to refer only to varieties of ''Cannabis'' cultivated for non-drug use. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cannabis」の詳細全文を読む スポンサード リンク
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