Other Definitions
juniper (dict)
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Juniper50-55 species; see text. Junipers are coniferous plants in the genus Juniperus of the cypress family Cupressaceae. There are about 50-55 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. 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 Common Juniper). 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. 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. 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. - Juniperus sect. Juniperus: Needle-leaf junipers. The adult leaves are needle-like, in whorls of three, and jointed at the base (see below right).
- Juniperus sect. Juniperus subsect. Juniperus: Cones with 3 separate seeds; needles with one stomatal band.
- Juniperus sect. Juniperus subsect. Oxycedrus: Cones with 3 separate seeds; needles with two stomatal bands.
- Juniperus sect. Juniperus subsect. Caryocedrus: Cones with 3 seeds fused together; needles with two stomatal bands.
- Juniperus sect. Sabina: Scale-leaf junipers. The adult leaves are mostly scale-like, similar to those of cypresses, in opposite pairs or whorls of three, and the juvenile needle-like leaves are not jointed at the base (including in the few that have only needle-like leaves; see below right).
- Provisionally, all the other junipers are included here, though they form a paraphyletic group.
Additional notes 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 Chinese Juniper J. chinensis from East Asia) are extensively used in landscaping and horticulture. Some junipers are sometimes misleadingly called cedars, the common name for species in the genus Cedrus, family Pinaceae. Some junipers are susceptible to Gymnosporangium rust disease, and can be a serious problem for those growing Apples, the alternate host of the disease. External links
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