Xanthocyparis

Nootka cypress ( Xanthocyparis nootkatensis )

Xanthocyparis is a plant genus in the family of the cypress family ( Cupressaceae ). It was not described until 2002. The genus name Xanthocyparis means " yellow cypress " and refers to the color of the wood.

• 4.1 Notes and references

Vegetative characteristics

Xanthocyparis species grow as small to large, evergreen trees. The bark is fibrous, and peels off in longitudinal strips. The heartwood is yellowish and grows slowly. They form a pyramidal, conical or irregular, flat crown above. The seedlings have two seed leaves ( cotyledons ), the result leaves are linealische juvenile needle leaves in Viererwirteln.

The leafy branches are horizontal or slightly drooping. There are three types of Beblätterung: linealische acicular Juvenilblätter, transitional leaves and scale-like adult leaves. Juvenilblätter are either only available to the seedlings or on adult trees. You are in whorls four and protrude radially from the axis from. Branches with this Beblätterung are sterile. Transition leaves also occur only on seedlings or on adult trees. Adult leaves are found only on adult trees. You are decussate, and have two sizes and shapes: the side are strongly flattened. Branches with adult leaves are often fertile and bear cones.

Generative features

Xanthocyparis species are monoecious getrenntgeschlechtig ( monoecious ). The pollen cones are forming terminally and singly on small branches with leaves shed. They are 2.5 to 5 × 2 to 2.5 mm in size and carry 10 to 16 Mikrosporophylle. These are opposite, shield-shaped and wear two (rarely three) large microsporangia.

The seed-bearing cones are terminally and singly on Seitenzwiegen with shed leaves. Mature cones are 7 to 11 × 10 to 12 mm in size, if they open up even further. The bract - scale complexes are (rarely three) against permanent pairs in two. They are fused at the base. The upper pair is quite overgrown, and opens for releasing the seeds far. They are easy to fold shield-shaped, and have a central umbo. The central axis of the pin is small and can even be completely absent. The ovules are axillary to the bracts, each bract cleaning difficult one to five ovules, of which are usually the less seeds. Most only develop on the upper bract - scale complex pair of seeds. The seeds are flattened and have two lateral wings.

Dissemination

The genus Xanthocyparis has a strongly disjoint area. One of the two species occurs in North America and the second in the north of Vietnam.

System

The genus is placed in the subfamily Cupressoideae, their closest relatives are Cupressus and Juniperus.

The genus two species are counted:

• Nootka cypress ( Xanthocyparis nootkatensis ) from North America was formerly in genus Chamaecyparis, and transferred in 2002 after the discovery of VietNamian type in the new class.
• Xanthocyparis vietnamensis. The discovery of this type Vietnamese in 1999 led to the formation of new species in 2002.

The close relationship of the two species was undisputed. However, Little and colleagues found out in 2004 that the Nootka cypress was described in 1865 by Oersted under the generic name Callitropsis. The name was never used. They transferred the two species in the genus Callitropsis Oerst. This was objected in 2006 by Miller and Farjon who proposed the preservation of the name Xanthocyparis over the older Callitropsis. This proposal was in 2007 by the Nomenclature Committee for Vascular Plants in favor of a decision on the acceptance of Xanthocyparis as a noun conservandum 2011 will fall at the next International Botanical Congress.

Documents

• A. Farjon, Nguyen Tien Hiep, DK Harder, Phan Ke Loc, L. Averyanov: A New Genus and Species in Cupressaceae ( Coniferales ) from Northern Vietnam, Xanthocyparis vietnamensis. Novon, Volume 12, 2002, pp. 179-189.