The blue spruce (''Picea pungens''), also commonly known as green spruce, Colorado spruce, or Colorado blue spruce, is a
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 (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
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 entert ...
to North America, and is found in USDA
growing zones 1 through 7. It is found naturally in Arizona, Colorado, Idaho, New Mexico, Utah and Wyoming. 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 colored needles and is a
coniferous
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant ...
tree.
Description
In the wild, ''Picea pungens'' grows to about , but when planted in parks and gardens it seldom exceeds tall by wide. The tree can grow larger if the tip is cut when it is at least 3 years old. It is a columnar or conical
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 ...
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](_blank)
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.
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 of living things by giving each a name composed of two parts, bot ...
''pungens'' means "sharply pointed", referring to the leaves.
The blue spruce is the
state tree
This is a list of U.S. state, federal district, and territory trees, including official trees of the following of the states, of the federal district, and of the territories.
Table
See also
* List of U.S. state, district, and territorial insign ...
of
Colorado.
Cultivation
''Picea pungens'' and its many
cultivars are often grown as
ornamental tree
Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...
s in gardens and parks.
It is also grown for the
Christmas tree
A Christmas tree is a decorated tree, usually an evergreen conifer, such as a spruce, pine or fir, or an artificial tree of similar appearance, associated with the celebration of Christmas. The custom was further developed in early modern ...
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 of the
pineapple gall adelgid 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 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 Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...
, 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
spruce beetle
''Dendroctonus rufipennis'', the spruce beetle, is a species of bark beetle native to British Columbia, Newfoundland and Labrador, Nova Scotia, Ontario, Quebec, Northern Manitoba, the Yukon, Colorado, Wyoming, Montana, and Maine. They are known ...
(''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
A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticultur ...
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 have 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
The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions.
History
The 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
The Navajo (; British English: Navaho; nv, Diné or ') are a Native American people of the Southwestern United States.
With more than 399,494 enrolled tribal members , the Navajo Nation is the largest federally recognized tribe in the United ...
and 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' 2006-05-03.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) description
Lady 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 the Western 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