Juniper

From Academic Kids

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Juniperus
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Jeneverbes.jpg



Juniperus communis shrubs
in The Netherlands
Scientific classification
Kingdom:Plantae
Division:Pinophyta
Class:Pinopsida
Order:Pinales
Family:Cupressaceae
Genus:Juniperus
Species

50-55 species; see text.

Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. Depending on taxonomic viewpoint, there are between 50-67 species of juniper, widely distributed throughout the northern hemisphere, from the arctic, south to tropical Africa in the Old World, and to the mountains of Central America in the New World.

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Jun_com_cones.jpg
Cones and leaves of Juniperus communis

Junipers vary in size and shape from tall trees to 20-40 m tall, to columnar or low spreading shrubs with long trailing branches. They are evergreen with either needle-like and/or scale-like leaves. They can be either monoecious or dioecious. The female seed cones are very distinctive, with fleshy, fruit-like coalescing scales which fuse together to form a "berry"-like structure, 4-27 mm long, with 1-12 unwinged, hard-shelled seeds. In some species these "berries" are red-brown or orange but in most they are blue; they are often aromatic (for their use as a spice, see Juniperus communis). The seed maturation time varies between species from 6-18 months after pollination. The male cones are similar to those of other Cupressaceae, with 6-20 scales; most shed their pollen in early spring, but some species pollinate in the autumn.

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Jun_chin_close.jpg
Detail of Juniperus chinensis shoots, with juvenile (needle-like) leaves (left), and adult scale leaves and immature male cones (right)

Many junipers (e.g. J. chinensis, J. virginiana) have two types of leaves: seedlings and some twigs of older trees have needle-like leaves 5-25 mm long; and the leaves on mature plants are (mostly) tiny (2-4 mm long), overlapping and scale-like. When juvenile foliage occurs on mature plants, it is most often found on shaded shoots, with adult foliage in full sunlight. Leaves on fast-growing 'whip' shoots are often intermediate between juvenile and adult.

In some species (e.g. J. communis, J. squamata), all the foliage is of the juvenile needle-like type, with no scale leaves. In some of these (e.g. J. communis), the needles are jointed at the base, in others (e.g. J. squamata), the needles merge smoothly with the stem, not being jointed.

The needle-leaves of junipers are hard and sharp, making the juvenile foliage very prickly to handle. This can be a valuable identification feature in seedlings, as the otherwise very similar juvenile foliage of cypresses (Cupressus, Chamaecyparis) and other related genera is soft and not prickly.

Contents

1 References
2 External links

Classification

The number of juniper species is disputed, with two recent studies giving very different totals, Farjon (2001) accepting 52 species, and Adams (2004) accepting 67 species. The junipers are divided into several sections, though (particularly among the scale-leaved species) which species belong to which sections is still far from clear, with research still on-going. The section Juniperus an obvious monophyletic group though.

Juniper needles, magnified. Left, Juniperus communis (Juniperus sect. Juniperus; note needles 'jointed' at base). Right, Juniperus chinensis (Juniperus sect. Sabina; note needles merging smoothly with the stem, not jointed at base).
Enlarge
Juniper needles, magnified. Left, Juniperus communis (Juniperus sect. Juniperus; note needles 'jointed' at base). Right, Juniperus chinensis (Juniperus sect. Sabina; note needles merging smoothly with the stem, not jointed at base).
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Juniper_berries_q.jpg
An Eastern Juniper in October laden with ripe cones.

Additional notes

Some junipers are susceptible to Gymnosporangium rust disease, and can be a serious problem for those growing Apples, the alternate host of the disease.

The Rocky Mountain Juniper (J. scopulorum), One-seed Juniper (J. monosperma), Western Juniper (J. occidentalis), Utah Juniper (J. osteosperma) and California Juniper (J. californica) occur in the western United States. In the southwest United States there are four more species, including the Alligator Juniper (J. deppeana) with its thick bark checkered into scaly squares.

Many of the earliest prehistoric people lived in or near juniper forests which furnished them food, fuel, and wood for shelter or utensils. Many species (such as J. chinensis (Chinese Juniper, 柏) from East Asia) are extensively used in landscaping and horticulture, it is also a symbol of longevity.

Juniper berries are used in the brewery of gin.

Some junipers are sometimes misleadingly called cedars, correctly the vernacular name for species in the genus Cedrus, family Pinaceae.

References

  • Adams, R. P. 2004. Junipers of the World: The genus Juniperus. Trafford (http://www.trafford.com/4dcgi/view-item?item=7594&1335646-30936aaa). ISBN 1-4120-4250-X
  • Farjon, A. 2001. World Checklist and Bibliography of Conifers. Kew. ISBN 1-84246-025-0

External links

Template:Commonsda:Enebr (Juniperus) de:Wacholder eo:Junipero et:kadakas fr:Genvrier it:Juniperus nl:Jeneverbes no:Einer zh:杜松子

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