|
Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America. Recent classification systems of the genus recognize ten to thirteen species in two distinct subgenera, ''Engleriana'' and ''Fagus''.〔Denk, Thomas with Guido Grimm and Vera Hemleben. 2005. Patterns of Molecular and Morphological Differentiation in ''Fagus'' (Fagaceae): Phylogenetic Implications. American Journal of Botany 92(6):1006-1016.〕〔Shen, Chung-Fu. 1992. A Monograph of the Genus ''Fagus'' Tourn. Ex L. (Fagaceae). Ph.D. Dissertation, City University of New York.〕 The ''Engleriana'' subgenus is found only in East Asia, and is notably distinct from the ''Fagus'' subgenus in that these beeches are low-branching trees, often made up of several major trunks with yellowish bark. Further differentiating characteristics include the whitish bloom on the underside of the leaves, the visible tertiary leaf veins, and a long, smooth cupule-peduncle. ''Fagus japonica'', ''Fagus engleriana'', and the species ''F. okamotoi'', proposed by the bontanist Chung-Fu Shen in 1992, comprise this subgenus.〔 The better known ''Fagus'' subgenus beeches are high-branching with tall, stout trunks and smooth silver-grey bark. This group includes ''Fagus sylvatica'', ''Fagus grandifolia'', ''Fagus crenata'', ''Fagus lucida'', ''Fagus longipetiolata'', and ''Fagus hayatae''.〔 The classification of the European beech, ''Fagus sylvatica'' is complex, with a variety of different names proposed for different species and subspecies within this region (for example ''Fagus taurica'', ''Fagus orientalis'', and ''Fagus moesica''〔Gomory, D. with L. hi , R. Brus, P. Zhelev, Z. Tomovic, and J. Gracan. 1999. Genetic differentiation and phylogeny of beech on the Balkan peninsula. Journal of Evolutionary Biology 12: 746-752.〕). Research suggests that beeches in Eurasia differentiated fairly late in evolutionary history, during the Miocene. The populations in this area represent a range of often overlapping morphotypes, though genetic analysis does not clearly support separate species.〔Denk, Thomas with Guido Grimm, K. Stogerer, M. Langer, Vera Hemleben 2002. The evolutionary history of ''Fagus'' in western Eurasia: Evidence from genes, morphology and the fossil record. Plant Systematics and Evolution 232:213-236.〕 Within its family, the Fagaceae, recent research has suggested that ''Fagus'' is the evolutionarily most basal group.〔Manos, Paul S. with Kelly P. Steele. 1997. Phylogenetic analysis of “Higher” Hamamelididae based on Plasid Sequence Data. American Journal of Botany 84(10):1407-1419.〕 The southern beeches (''Nothofagus'' genus) previously thought closely related to beeches, are now treated as members of a separate family, Nothofagaceae. They are found in Australia, New Zealand, New Guinea, New Caledonia, Argentina and Chile (principally Patagonia and Tierra del Fuego). The European beech (''Fagus sylvatica'') is the most commonly cultivated, although there are few important differences between species aside from detail elements such as leaf shape. The leaves of beech trees are entire or sparsely toothed, from 5–15 cm long and 4–10 cm broad. Beeches are monoecious, bearing both male and female flowers on the same plant. The small flowers are unisexual, the female flowers borne in pairs, the male flowers wind-pollinating catkins. They are produced in spring shortly after the new leaves appear. The bark is smooth and light grey. The fruit is a small, sharply three–angled nut 10–15 mm long, borne singly or in pairs in soft-spined husks 1.5–2.5 cm long, known as cupules. The husk can have a variety of spine- to scale-like appendages, the character of which is, in addition to leaf shape, one of the primary ways beeches are differentiated.〔 The nuts are edible, though bitter (though not nearly as bitter as acorns) with a high tannin content, and are called beechnuts or beechmast. The name of the tree (Latin fagus, whence the species name; cognate with English "beech") is of Indo-European origin, and played an important role in early debates on the geographical origins of the Indo-European people. Greek φηγός is from the same root, but the word was transferred to the oak tree (e.g. Iliad 16.767) as a result of the absence of beech trees in Greece.〔Robert Beekes, Etymological Dictionary of Greek, Leiden and Boston 2010, pp. 1565–6〕 ==Habitat== Beech grows on a wide range of soil types, acidic or basic, provided they are not waterlogged. The tree canopy casts dense shade, and carpets the ground thickly with leaf litter. In North America, they often form beech-maple climax forests by partnering with the sugar maple. The beech blight aphid (''Grylloprociphilus imbricator'') is a common pest of American beech trees. Beeches are also used as food plants by some species of Lepidoptera (see list of Lepidoptera that feed on beeches). Beech bark is extremely thin and scars easily. Since the beech tree has such delicate bark, carvings, such as lovers' initials and other forms of graffiti, remain because the tree is unable to heal itself.〔Lawrence, Gale. A Field Guide to the Familiar: Learning to Observe the Natural World. Hanover: University Press of New England, 1984. 75-76. Print.〕 Beech bark disease is a fungal infection that attacks the American beech through damage caused by scale insects.〔"beech." The Columbia Encyclopedia. New York: Columbia University Press, 2008. Credo Reference. Web. 17 September 2012.〕 Infection can lead to the death of the tree .〔beech bark disease." Dictionary of Microbiology & Molecular Biology. Hoboken: Wiley, 2006. Credo Reference. Web. 27 September 2012.〕 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「beech」の詳細全文を読む スポンサード リンク
|