blue spruce
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The blue spruce (''Picea pungens''), also commonly known as green spruce, white spruce, Colorado spruce, or Colorado blue spruce, is a
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
of
spruce A spruce is a tree of the genus ''Picea'' , a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Earth. ''Picea'' is the sole genus ...

spruce
tree. It is
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entertain ...

native
to North America, and is found in USDA growing zones 1 through 7. Its natural range extends from northern New Mexico through Colorado and Utah to Wyoming and into Alberta and British Columbia, but it has been widely introduced elsewhere and is used as an ornamental tree in many places far beyond its native range. The blue spruce has blue-green coloured needles and is a coniferous tree.


Description

In the wild, ''Picea pungens'' grows to about , but when planted in parks and gardens it seldom exceeds tall by wide. It is a columnar or conical
evergreen In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Anci ...

evergreen
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ex ...

conifer
with densely growing horizontal branches. It has scaly grey bark on the trunk with yellowish-brown branches. Waxy gray-green leaves, up to long, are arranged radially on the shoots which curve upwards. The pale brown cones are up to long.USDA
Accessed 2012-12-01
Male cones are found on the entire tree, whereas the female cones are found at the top of the tree. This helps to facilitate
cross-pollination Pollination is the transfer of pollen File:Pollen Tube.svg, Pollen Tube Diagram Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes (sperm ...
. The
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species In biology, a species is the basic unit of biological classi ...
''pungens'' means "sharply pointed", referring to the leaves. The blue spruce is the state tree of
Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wester ...

Colorado
.


Cultivation

''Picea pungens'' and its many
cultivar A cultivar is a type of plant that people have bred for desired traits, which are reproduced in each new generation by a method such as grafting, tissue culture or carefully controlled seed production. Most cultivars arise from purposeful human ...
s are often grown as
ornamental tree plant Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as houseplants, cut flowers and specimen display. The cultivation of ornamental plants comes under floriculture, which is a major ...

ornamental tree
s in gardens and parks. It is also grown for the
Christmas tree A Christmas tree is a decorated tree, usually an evergreen In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist wh ...

Christmas tree
industry.


Pests and diseases

The blue spruce is attacked by two species of ''
Adelges ''Adelges'' is a genus of insects which feed on conifers. Excepting galls formed by the spruce gall midge, galls are caused by aphid-like insects of the superfamily Phylloxeroidea (family Adelgidae) commonly known as the spruce gall adelgids. Th ...
'', an aphid-like insect that causes galls to form.
Nymphs A nymph ( el, νύμφη, ; Ancient Ancient history is the aggregate of past eventsWordNet Search ...
of the
pineapple gall adelgid branch. The Pineapple gall adelgid (''Adelges abietis'') is a type of conifer-feeding insect that forms pineapple-shaped plant galls on its host species, commonly Norway spruce, Norway and Sitka spruce. The adelgids (genus ''Adelges'') are pear-s ...
form galls at the base of twigs which resemble miniature pineapples and those of the Cooley's spruce gall adelgid cause cone-shaped galls at the tips of branches. The larva of the
spruce budworm ''Choristoneura'' is a genus of moths in the family Tortricidae The Tortricidae are a family of moth Moths are a paraphyletic group of insects that includes all members of the Order (biology), order Lepidoptera that are not Butterfly, butt ...
eat the buds and growing shoots while the spruce needle miner hollows out the needles and makes them coalesce in a webbed mass. An elongated white
scale insect Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient gr ...

scale insect
, the pine needle scale feeds on the needles causing fluffy white patches on the twigs and aphids also suck sap from the needles and may cause them to fall and possibly dieback. Mites can also infest the blue spruce, especially in a dry summer, causing yellowing of the oldest needles. Another insect pest is the Dendroctonus rufipennis, spruce beetle (''Dendroctonus rufipennis'') which bores under the bark. It often first attacks trees which have blown over by the wind and when the larvae mature two years afterwards, a major outbreak occurs and vast numbers of beetles attack nearby standing trees. The blue spruce is susceptible to several needle casting diseases which cause the needles to turn yellow, mottled or brown before they fall off. Various rust diseases also affect the tree causing yellowing of the needles as well as needle fall. Canker caused by ''Cytospora'' attacks one of the lower branches first and progressively makes its way higher up the tree. The first symptom is the needles turning reddish-brown and falling off. Meanwhile, patches of white resin appear on the bark and the branch eventually dies.


Rooting Habits

Blue spruce seedlings are shallow roots that penetrate only 6.4 cm (2.5 inches) of soil during the first year. Although freezing can't damage much in blue spruce, frost will cause seedling loss. Shadows in late spring and early autumn minimize this frost heaving loss. Despite the shallow roots, blue spruce is able to resist strong winds. Five years before transplanting, the total root surface area of 2-meter-high trees was doubled by pruning the roots of blue spruce. It also increases the root concentration in drip irrigation pipeline from 40% to 60%, which is an advantage in landscape greening.


Cultivars

Common cultivars (those marked have gained the Royal Horticultural Society's Award of Garden Merit): *'Glauca Globosa' – shrub from in height *'Fat Albert' – compact perfect cone to of a silver blue color *'Glauca Jean's Dilly' – shrub from in height *'Glauca Pendula' – drooping branches, spreads to about wide by tall *'Hoopsii' *'Koster' *'Baby Blue Eyes' *'Baby Blue'


Uses

The Navajo people, Navajo and Keresan languages, Keres Native Americans use this tree as a traditional medicinal plant and a ceremonial item, and twigs are given as gifts to bring good fortune. In traditional medicine, an infusion of the needles is used to treat colds and settle the stomach. This liquid is also used externally for rheumatic pains. Early people used their wood for building.


Gallery

File:Picea pungens Žilina.JPG, Mature tree File:Picea pungens2.jpg, Mature cone File:Picea Pungens Young Cones.jpg, Immature cone File:Picea_pungens_Hoopsii201601.jpg, Hoopsii File:Picea pungens 'Koster' Lappen nursery.jpg, Koster File:Picea pungens Globosa2.jpg, Globosa File:Picea pungens Montgomery.jpg, Montgomery File:Fat Albert Colorado spruce.jpg, Fat Albert


Distributed soil types and topography

Blue spruce generally exists on gentle uplands and sub irrigated slopes, in well-watered tributary drainage, extending down intermittent streams, and on lower northerly slopes. Blue spruce always grow naturally in the soils which are in the order Mollisols, and the soil will also be in the orders histosols and inceptisols in a lesser extent. Blue spruce is considered as a pioneer tree species in moist soil in Utah.


Climate

Blue spruce usually grows in cool and humid climatic zones where the annual precipitation mainly occurs in the summer. Blue spruce is most common in Colorado and the Southwest. The annual average temperature ranges from 3.9 to 6.1 degrees C (39 to 43 degrees F). And ranges from - 3.9 to - 2.8 degrees C (25 to 27 degrees F) in January. In July, the average temperature ranges from 13.9 to 15.0 degrees C (57 to 59 degrees F). The average minimum temperature in January ranges from - 11.1 to 8.9 degrees C (12 to 16 degrees F), and the average maximum temperature in July ranges from 21.1 to 22.2 C (70 to 72 degrees F). There is a frost-free period of about 55 to 60 days from June to August. Annual mean precipitation generally vary from 460 to 610 mm (18 to 24 in). Winter is the season with the poorest rainfall, the precipitation is usually less than 20 percent of the annual moisture falling from December to March. And fifth percent of the annual precipitation occurs during the growing season of the plants. Blue spruce is generally considered to grow best with abundant moisture. Nevertheless, this species can withstand drought better than any other spruce. It can withstand extremely low temperatures (-40 degrees C) as well. Furthermore, this species is more resistant to high insolation and frost damage compared to other associated species.


References


External links


Conifers.org: Picea pungens (blue spruce) descriptionLady Bird Johnson Wildflower Center NPIN
— Native Plant Information Network
Interactive Distribution Map of ''Picea pungens''''Picea pungens''
— U.C. Photo Gallery {{Authority control Picea Trees of North America Trees of Canada Trees of the United States Trees of Eastern Canada Trees of the Northeastern United States Trees of the Western United States Trees of the Northwestern United States Trees of the South-Central United States Trees of the Southwestern United States Flora of the Rocky Mountains Least concern flora of the United States Symbols of Colorado Plants used in traditional Native American medicine Garden plants of North America Ornamental trees Plants described in 1879