Juglans

Walnut ( Juglans regia)

The walnuts ( Juglans ) are a genus of the family of the walnut family ( Juglandaceae ). There are mainly trees whose nut fruits are in some species of great economic importance. In Central Europe is mainly the common walnut ( Juglans regia) to be found, much less cultivated or wild the black walnut ( Juglans nigra).

Features

The representatives are deciduous trees or large shrubs. The branches have a chambered Mark. The buds have a few bud scales, the terminal bud is enlarged. The lateral buds are sitting.

The leaves are alternate, pinnate, large, aromatic, and without stipules. They consist of 5 to 31 leaflets. Rarely the terminal leaflets is reduced. The leaf margin serrate or entire, the leaf blade is provided on the underside with glandular dots.

The plants are monoecious. The male catkins are individually laterally to vorjährigem wood. They are in the axils of leaf scars, are sessile and hanging. The immature, naked kittens appear in late summer in the leaf axils and overwinter as small, bud-like structures. The female ear consists of 2 to 25 single flowers and is terminally at this year's shoots. Male and female flowers are on a supporting sheet and have two Brakteolen, and four sepals. In the male flowers the sepal number is often reduced. The support sheet is small, narrow, not lobed. The male flower bears 7-85 (rarely to 105) stamens, which are apparently on bract, Brakteolen and sepals, as they are fused with the base of the flower. The anthers are glabrous, sometimes slightly hairy. The female flowers consist of the support sheet, two Brakteolen, whose free ends are lobed and four sepals. All are with the tip of the ovary fused except at their tips. The ovary is thus under constant. It consists of two carpels, which are located medially in individual flowers are rare even 3 or 4 carpels. The stylus supports two extended curved stylus branches on the inside of the scars sitting cushion.

The fruits are large and resemble stone fruits ( and in German literature often referred to as stone fruits). They consist of a ridged or wrinkled, nut fruit, which is surrounded by her adherent, thick, fibrous, and usually not open envelope. This case is illustrated by the bracts and the calyx. The wooden walnut wall, the pericarp, usually has significant Wandhöhlungen. At the base of the nut is two or vierfächrig. The cotyledons are fleshy, vierlappig and straight. In each flap sits one cotyledon. Germination is hypogeous. The nodes of the cotyledons has 2-4 lacunae and as many leaf traces.

Dissemination

The walnuts are the only genus Carya next to the family, which occurs both in the New as the Old World. Their main area of ​​distribution are the temperate to subtropical areas of the northern hemisphere. In America, their area ranges from southern Canada to northern Argentina. In Asia it occurs in eastern China, Manchuria, Korea and Japan. The walnut is the only front in Europe, their natural area should the Balkans and the Middle East to be. Their stocks from the Caucasus to western China could be caused by humans.

System

The genus forms a natural kinship group, is therefore monophyletic. Within the family, the walnut family and the subfamily Juglandoideae Juglans together with Pterocarya and Cyclocarya, whose sister group it is, the subtribe Juglandinae. The genus name Juglans is generalized from the Latin name for the walnut; he is the genitive addition * Di̯ou̯es glans, acorn of Jupiter ' returned, which itself agr Διὸς βάλανος Dios BALANOS, sweet chestnut, ( sort of) Sap appears to be modeled.

Since the work of LA Dode 1906/1909 the genus Juglans is divided into four sections. They have been adopted by most other agents of the genus and confirmed by molecular genetic studies. The subsections of Dode could not be confirmed by molecular genetic.

W. E. Manning lists 21 species. Partial separation or merging of individual species is discussed differently.

  • (Also called Dioscaryon ) Section Juglans Walnut ( Juglans regia)

The molecular genetic analysis of Stanford et al. (2000) included 15 of the 21 species and yielded the following relationships of sections:

Trachycaryon

Cardiocaryon

Dioscaryon

Rhysocaryon

Documents

  • Anmin Lu, Donald E. Stone & LJ Grauke: Juglandaceae, in: Flora of China, Volume 4, 1999, pp. 277-285. Science Press, Beijing and Missouri Botanical Garden Press, St. Louis. (pdf, 153 kB)
  • Wayne E. Manning: The classification within the Juglandaceae. Annals of the Missouri Botanical Garden, Volume 65, 1978, p 1058-1087.
  • Alice M. Stanford, Rachel Harden, Clifford R. Parks: Phylogeny and biogeography of Juglans ( Juglandaceae ) based on matK and ITS sequence data. American Journal of Botany, Volume 87, 2000, pp. 872-882.
Rosids Fagales Ovary (botany) Stigma (botany) Drupe Hickory Digital Object Identifier
109328
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