West American juniper

from Wikipedia, the free encyclopedia
West American juniper
West American juniper

West American juniper

Systematics
Order : Conifers (Coniferales)
Family : Cypress family (Cupressaceae)
Subfamily : Cupressoideae
Genre : Juniper ( Juniperus )
Section : Sabina
Type : West American juniper
Scientific name
Juniperus occidentalis
Hook.

The West American juniper ( Juniperus occidentalis ), also Western juniper called, is a plant from the family of the cypress family ( Cupressaceae ). It is native to western North America .

description

Habit, root system and bark

The West American juniper grows as an evergreen tree . The appearance as well as the height of growth depend strongly on the altitude, the amount of precipitation and the soil conditions. On deep soils and in a sheltered location, it can reach a maximum height of 22 meters. Old trees that grow near the tree line have unusually strong, twisted trunks and wide, wind-disheveled crowns that are provided with many dry branches.

The West American juniper has a very strong, deep and extensive root system. It is able to find support even in crevices and to supply the tree with water.

The red-brown bark is longitudinally fissured and only covers the trunk of heavily exposed old trees in narrow strips. The gray-brown bark of young trees comes off in large scales. Strong twigs have a red-brown bark that peels off in thin, paper-like scales.

Wood

The almost white sapwood surrounds the hard and relatively heavy reddish heartwood . It is very durable and has a very aromatic smell.

leaves

Branches with leaves of the West American juniper

The numerous scale leaves, arranged opposite or in threes in whorls , close to strong branches, are gray-green, about 3 millimeters long and have a finely toothed edge. With young and strong twigs, the leaf tips stick out a little. The leaves, surrounded by a thick membrane ( cuticle ), have no stomata to adapt to the dry climate . On the curved back of the scale leaves there is a clearly recognizable resin gland, which secretes a resin-like liquid in autumn . Seedlings have very pointed and sub-shaped needles about 1.3 centimeters long.

Flowers, cones and seeds

Branches with ripe cones of the West American juniper

The West American juniper is mostly monoecious ( monoecious ), rarely dioecious ( dioecious ) separate sexes. The flowering period extends from April to May. The male flowers have 12 to 18 stamens. The female cone flowers have pointed ovoid ovules , which are enclosed by fleshy scale leaves after pollination. The 6 to 8 millimeter thick berry cones ripen in autumn of the second year. They are frosted blue-black and white when ripe. The thin and resinous “pulp” is surrounded by a firm shell. They stay on the tree in winter. Each berry cone contains two to three hard-shell seeds that are about 3 millimeters long. They are somewhat pointed and have a raised back and a flat front. The thousand grain weight is around 37 grams. The diaspores are largely spread via birds ( ornithochory ).

Chromosome number

The number of chromosomes in the nominate form is 2n = 22.

Distribution and location

Map of the distribution area
Grove of West American junipers

The focus of the distribution area of ​​the West American juniper lies in the very dry steppes of central and southern Oregon . The northernmost point of the natural occurrence is isolated small deposits in central and southern Washington . The eastern border forms an also isolated population in the extreme southwest of Idaho . The southern border runs through the northern California location, Lassen County and northern Nevada . Its range overlaps with that of the Rocky Mountain Juniper ( Juniperus scopulorum ).

This species needs light, is drought-resistant, undemanding and resistant to cold, heat, wind, snowstorms and summer thunderstorms with lightning and the resulting fires. It inhabits locations with annual precipitation of around 230 to 355 mm and occurs at heights of 200 to 3,100 meters. Even heavily exposed rocks are populated. The West American juniper hardly forms mixed stands with other tree species. An accompanying tree species that are ponderosa pine ( Pinus ponderosa ) or Cercocarpus ledifolius observed. In the higher settlement areas the coastal pine ( Pinus contorta subsp. Latifolia ) and the mountain Douglas fir ( Pseudotsuga menziesii var. Glauca ) are mentioned.

use

Due to the inaccessible locations, the West American juniper is of little economic importance. Since the wood is very resistant even when it comes into contact with the ground, fence posts are occasionally made from it. It would also be suitable for making furniture, panels and veneers . The essential oil, which can be extracted from the heartwood of this and other juniper species, is used as an odor component in soaps, sprays and disinfectants and as immersion oil in microscopy. The resin is said to have been used by the Californian Indians to attach feathers to their arrows .

Systematics

Juniperus occidentalis is assigned to the subgenus Sabina and the section Occidentalis within the genus Juniperus . The species in this section have finely toothed leaves and the berry cones are dark blue when ripe. Other sources, however, list the sub-genus Sabina as the Sabina section without any further subdivisions. A synonym for Juniperus occidentalis Hook. is Juniperus andina Nutt.

Different sources divide the species into the two subspecies Juniperus occidentalis Hook. subsp. occidentalis - the nominate form - and the southern subspecies Juniperus occidentalis Hook. subsp. australis vasek . According to new studies, this subspecies was given species status as Juniperus grandis R.P. Adams.

Hazards and protective measures

The West American juniper is included in the Red List of Endangered Species by the International Union for Conservation of Nature ( IUCN ), but it is designated as “Least Concern”. It was found that the population and distribution of the species are increasing sharply as grazing by livestock is declining, which means that seedlings are better protected from the elements and herbivores.

In the USA this juniper species is placed under protection in the state of Nevada by restricting its use.

swell

literature

  • Peter Schütt, Horst Weisgerber, Hans J. Schuck, Ulla Lang, Bernd Stimm, Andreas Roloff: Lexicon of Conifers. Distribution - Description - Ecology - Use; the great encyclopedia . Nikol, Hamburg 2004, ISBN 3-933203-80-5 , p. 213-218 .
  • Robert P. Adams: Juniperus . In Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 2: Pteridophytes and Gymnosperms . Oxford University Press, New York / Oxford a. a. 1993, ISBN 0-19-508242-7 (English). ( Juniperus occidentalis online).

Individual evidence

  1. ^ Tropicos. [1]
  2. ^ Robert P. Adams, Sanko Nguyen, Julie A. Morris, Andrea E. Schwarzbach: Re-Examination of the Taxonomy of the One-Seeded, Serrate Leaf Juniperus of Southwestern United States and Northern Mexico . In: Phytologia . tape 88 , no. 3 , 2006, p. 299 (English, juniperus.org [PDF]).
  3. ↑ Juniperus occidentalis in the endangered Red List species the IUCN 2013. Posted by: A. Farjon, 2011. Accessed July 17, 2020th
  4. ↑ Christmas Trees, Cacti, and Yucca Native to Nevada. (No longer available online.) In: NRCS Natural Resources Concervation Service. Department of Conservation and Natural Resources, archived from the original on March 28, 2010 ; accessed on June 6, 2010 (English). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / heritage.nv.gov

Web links

Commons : West American Juniper ( Juniperus occidentalis )  - Album with pictures, videos and audio files