How do spruce trees reproduce?

Planting blue spruce tree is rewarding; it is an attractive native American conifer, read below to know more about blue spruce care and growing.

Colorado Blue Spruce (Picea pungens) is a beautiful native American conifer. This extremely rustic silvery blue tree reaches the height of 9 – 21 m (30-70 ft) in its region of origin. Nice bluish green color, accentuated by the sharply pointed foliage makes it a perfect conifer for open landscapes and large backyards. Dwarf forms of blue spruce are also available that reaches only between 1.5 to 4.5 m (5-15 ft) tall and are suitable for small gardens, patios, and terraces.

This pyramidal conifer has a habit of growing slowly. Its persistent and fragrant needle-like bluish green foliage are densely distributed around the reddish gray twigs. These needles are stiff and sharp.

USDA Hardiness Zones — 3 – 8

Difficulty — Easy

Other Names — Blue Spruce, Green Spruce, White Spruce, Colorado Spruce or Colorado Blue Spruce and Picea Pungens.

Propagation and Planting Blue Spruce

Blue spruce is usually propagated by cuttings, graftings, and seeds. Blue spruce cuttings are collected, preferably in the morning from vigorous branches. These cuttings should be dipped in a rooting hormone before planting in containers in a mixture of peat and sand. After planting keep the cuttings in a bright spot and keep the growing medium moist. These cuttings take a long time to show signs of growth, and you must wait several months, and the success rate is also poor. Once the cuttings show growth, plant them in the right place. Air layering of the blue spruce tree is also possible.

Only mature blue spruce trees produce the cones. These cones drop their seeds in spring. Blue spruce seeds require a considerable period of light to germinate: 14 to 16 hours per day. If the length of light falls below 12 hours a day, they become dormant. Seedling Growth of blue spruce is also very slow, and you need to be patient.

If you are planting a blue spruce tree, our recommendation is to buy a plant from nursery so that you’ll not have to wait for that much long.

Position

Planting a blue spruce tree on location in moist soil with full sun to light shade is optimal. However, blue spruce trees can tolerate less than perfect conditions but growing them in a heavily polluted area can affect the blue color coating of the needles.

Blue Spruce Care

Blue spruce tree care involves a few requirements and slight maintenance to keep it healthy and vigorous.

Soil

Soil should be well-drained and rich in organic matter. You can add compost while planting. It is also required to keep the soil slightly moist when the plant is young as mature trees can tolerate dry soil.

Fertilizer

Conifer fertilizer is expensive (like 30-15-15 with minor elements) but very effective especially if your soil is sandy. These fertilizers will give all the nutrients and help the tree growing vigorously with a nice look and much denser foliage.

Water

Regular watering is required for the young plant. Once established, watering must be abundant but infrequent only during the dry spells. All conifers need a vital water supply in the fall before frost to accumulate reserves; this allows them to withstand the sun’s rays in March when plants still have their feet in the gel, causing called spring burn.

Weeds

Planting area around this magnificent conifer should be kept clean and weed free, especially when the plant is not well established. A good thick cedar mulch or of other organic matter is sufficient to prevent annual weeds.

Pruning

Do not prune these trees. They do best when their branches are allowed to grow all the way to the ground.

Pests and Diseases

Use a magnifying glass to examine the needles of your blue spruce for signs of Rhizosphaera needle cast (Rhizosphaera kalkhoffii), a fungus that causes needle cast disease. It pushes through the stomata of the affected needles and looks like fuzzy black spots. If not treated, blue spruce needles turn purple to brown and eventually fall. Although, the fungus doesn’t usually kill the tree. Besides this blue spruce trees are also susceptible to white pine weevils.

Growing New Spruce Trees – Learn How To Propagate A Spruce Tree

The birds do it, the bees do it, and spruce trees do it too. Spruce tree propagation refers to the different ways that spruce trees reproduce. How to propagate a spruce tree? The methods include growing spruce tree seeds and cuttings. If you are interested in learning about propagation methods for spruce trees, and how to start growing new spruce trees, read on.

Propagation Methods for Spruce Trees

In the wild, spruce tree propagation involves spruce seeds falling from the parent tree and beginning to grow in the soil. If you want to start growing new spruce trees, planting seeds is a common method of propagation.

Other propagation methods for spruce include rooting cuttings. Propagating spruce tree seeds and cuttings both produce viable plants.

How to Propagate a Spruce Tree with Seeds

How to propagate a spruce tree from seeds? The first thing you need to do is to buy the seeds or harvest them at the appropriate time. Harvesting seeds takes more time but less money than purchasing spruce seeds.

Collect seeds in mid-fall from a tree in your own yard or in a neighboring location with permission. Spruce seeds grow in cones, and it is these you want to collect. Pick them while they are young and before they are ripe.

You’ll need to extract the seeds from the cones. Let the cones dry out until they open and spill out the seeds. Count on this taking about two weeks. You may, but do not need to, treat the seeds in some way to help them to germinate, like scarification.

Plant the trees outdoors in late autumn or early spring. The trees will need water and light. Depending on your climate, rain can take care of the need for irrigation.

Spruce Tree Propagation from Cuttings

Take cuttings in late summer or early fall. Choose healthy shoots and clip off each about as long as your palm. Recut the base of the cutting at an angle and strip all needles from the lower two-thirds of each one.

Plant the cuttings deep into sandy loam. You can dip each cut end in rooting hormone before planting if desired, although it’s not required. Keep the soil moist and watch for roots to form.

How Does an Evergreen Tree Reproduce?

Evergreen trees, such as the pine, spruce and cedar, are known as conifers in the scientific world. They get the name because they don’t reproduce via fruit or flowers, like deciduous trees. Instead, their reproductive cycle takes place inside a pinecone–actually two pinecones, a male and female.

Pinecones

Most people don’t know that not all pinecones are created alike. Evergreen trees are asexual, meaning they can self-reproduce. To do this, they need two genders of pinecones. The male pinecone, or staminate cone, is usually smaller than the female, or ovulate, cone. The job of the male cone is to make pollen in its microsporangia, small sacs under each “leaf” of the cone. The female cone has ovules toward the center of its structure, each holding an egg cell.

The Process

The male cone distributes pollen to the female via the wind. Depending on the direction the wind blows, it can transfer the pollen to another cone on the same plant or to another evergreen tree nearby. The female cone, which is often closed at this point, giving it a soft, green appearance, collects the pollen and begins the process of meiosis, or cell division, so that it can produce more than one seed from each egg. Most often the “leaves” of the female cone, called “seed scales” end up with two seeds on the base of each scale. The rest of the scale forms a “wing,” which helps makes the seeds more aerodynamic.

Distribution

Once the seeds are fully developed, which in some species can take a year or longer, the female pinecone opens up, beginning to look like the crunchy brown pinecones we’re used to finding on the ground. This allows the seeds to fall out and flutter to the ground below or be carried further away by gusts of wind. In some species, a sticky substance, or “pitch,” near the base of the cone can attach to animals’ fur or feathers as they pass by the tree. This also helps spread the seeds to new areas. Eventually, the entire pinecone will detach from the evergreen tree and fall to the ground.

Seedlings

After the seed hits the forest floor, all it takes is a little water and sun to help the seedling take root. If you’ve ever been in the woods in an area with a relatively cold climate, you know that evergreen trees tend to be prolific. As the young tree grows, it begins to produce pinecones of its own and the reproductive cycle begins all over again.

White spruce

White spruce

Scientific Classification

  • Kingdom: Plantae
  • Division: Coniferophyta
  • Class: Pinopsida
  • Order: Pinales
  • Family: Pinaceae
  • Genus: Picea
  • Species: P. glauca

Binomial Name

Picea glauca

The White Spruce is also known as the Western White Spruce and Canadian Spruce. It’s mainly found in North America, but other places around the world as well. These trees can reach over 100 feet in height. They can grow in a variety of climates from moist to somewhat dry. This organism mainly reproduces by seeds. The seeds can either be blown by the wind, or carried off by animals such as squirrels.

Contents

  • 1 Anatomy
  • 2 Reproduction
  • 3 Ecology
  • 4 Related References

Anatomy

The needles on a branch of a White Spruce

The White Spruce is a medium sized tree. It is a conifer that is native to the U.S. and has a narrow “spire like crown.” These trees can reach over 100 feet in height. The trunk can have width of about a meter. The Spruce does not really have leaves, instead they have things that tend to look more like needles. Theses needles have four sides and are a bluish green color, averaging about three-quarters of an inch long. The branches of this magnificent plant are self pruning and protrude from the organism in dense clusters. The crown of the tree is about half way up. It doesn’t have a very thick bark, usually less than 0.3 inches in thickness. The outer covering can either be smooth or kind of scaly in a light grey brownish color. The roots usually extend to a depth of about 3 or 4 feet. The taproots and sinker roots will go even deeper to about 10 feet. In northern places, big roots can be found to be even within 6 inches of the mineral soil surface. The Spruce yields a fruit known as the cone. A brown, oval shaped cone, normally about 2 inches long. Which hangs by small stems on the upper branches of the crown.

Reproduction

The White Spruce has an extensive means of reproduction. Its main means of reproduction is by seeds. It’s also done vegetatively by a process called layering. The first of seed production occurs when the tree has existed for four years. Although, the seed process is not a great quantity until the organism is about 30 years or more old. The seeds are about an eighth of an inch long, and a quarter to a third of an inch wing. The main way that seeds are dispersed without human help is the wind. Most seeds tend to fall within about 300 feet of the place where it began. However, some have even been found to be almost a mile away! There are also red squirrels which carry the seeds off to different places. The seeds are only good for about 1-2 years. The seeds will sit over winter and germinate in the summer when the ground is nice and moist.

Ecology

A picture of the lower end of a White Spruce, showing its bark.

The White Spruce exists transcontinentally. These trees mainly exist in boreal forests. Loams, clays, and silt-loams are the main places where the White Spruce tends to thrive. Sandy soils, however, are some of the worst conditions for this plant. It does not grow well in places with a high water table. It will not live in places where there is stagnant water which reduces the root volume. On the other hand, it will exist in dry places, just as long as the climate is not too arid. The primary ways that these plants die are from stem and needle rusts, root diseases, weevils, and other wood eating insects.

Related References

  • The White Spruce
  • White Spruce By: Wikipedia
  • Pictures of White Spruce Trees By: Flikr
  • Boreal Forest
  • USDA White Spruce
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Biology of the Black Spruce – Part 2

By Johnny Caryopsis (Click links for more images.)

Classification

Here is the formal taxonomic classification of the black spruce.

Kingdom: Plantae
Division: Spermatophyta
Subdivision: Gymnospermae
Class: Coniferinae
Family: Pinaceae
Genus: Picea
Species: mariana

Name Derivation

The scientific name for black spruce works out like this:

“Picea” derives from the Latin word “pix” which means pitch. Pitch is a dark coloured resinous substance that was once used to caulk seams in wooden ships. In this case, the pitch refers to the resins that exuded from spruce and pine trees, although real pitch was derived from coal tars.

“mariana” derives from the New Latin word “marianus”, meaning “from Mary, the mother of Jesus”. (Interesting that this species was until recently the dominant Christmas trees in Manitoba!) The black spruce was first described in the early 1700’s as the “Maryland Spruce”, hence the “mariana” appellation, though it does not occur there. Remember, common and scientific nomenclature can often be quite a muddle!

The current common names of this species include black spruce, swamp spruce and bog spruce. The latter two names make sense as they relate to the habitat of the species, but I wasn’t able to track down how the common name of “black” spruce derives.

Habitat and Range

Black spruce is essentially a “Canadian” species; that is, the bulk of it’s North American range is in Canada. It is found in a few northeastern states in the US, as well as in Alaska. In Manitoba, this species occurs throughout the province except in the extreme north east, beyond the tree-line, and in the extreme south west, in the dry prairie region.

Typical habitat of black spruce and white spruce.

In the southern parts of its range the black spruce is usually found in habitats that have wet organic soils, such as peat bogs. Though they grow in places with very moist soil, they do not tolerate having their roots under water for long. It is common to see stands of dead black spruce where beavers have flooded adjacent bog lands. Black spruce can tolerate a variety of poor soil conditions, even growing on scarcely covered bare rocks. Further north it becomes more and more dominant on these kinds of conditions. In Manitoba it is one of only 2 or 3 tree species left at the tree-line that separates the last of the boreal forest from the arctic tundra. In the far north much of the black spruce’s habitat is underlain by permafrost. It’s thought that the tree’s shallow rooting habit plays a role in it’s dominance at these high latitudes. The roots of black spruce tend to spread out from the main trunk in a ring just at or below the soil surface, or right on top of the rocks in some case. They form a flattened circle about the tree, so the trunk is supported like a post sitting on a plate.

Black spruce stand in lowland.

Life Cycle

Every black spruce tree has grown from a tiny, winged seed (it would take 900 seeds to make 1 gm) that was released from its parent’s cone, fluttered to earth and happened to find the right conditions to germinate and grow. Under good growing conditions it may have reached 2-4 m in height by age 10, and 12 m by age 40 (tree growth rates are highly variable and dependent on many conditions). Black spruce can grow to reach heights up to 20 m and are thought to live as long as 280 years, though few are thought to reach this age, owing to the prevalence of forest fires and logging in the boreal forest.

The dominant feature in the life cycle of the black spruce, and all other coniferous trees, is the cone. A cone, which may also be called a “strobilus”, consists of a central axis which is surrounded by tightly packed, thick scales. There are male cones which produce pollen and female cones with egg cells where the seeds will ultimately develop. Both kinds of cones are found together on individual trees of most conifers, including the black spruce; that is, they are monecious. Female cones of black spruce are produced mainly in the upper crown of the tree (the top 1 or 2 m), with the male cones developing in the branches just below these.

Cones develop to the bud stage in the year prior to their use in reproduction. In the following spring, the small male cones (about 1.5 x 0.5 cm) swell and open in late May through early June, releasing yellow pollen grains on the wind. The female cones (about 2 x 1 cm) open at the same time and are pollinated by the wind borne pollen. The arrangement of male and female cones on individual trees, with female cones higher up, helps to promote cross-pollination from trees some distance away. After releasing pollen, the male cones shrivel and drop off. The female cones remain on the tree and the seeds mature about 3 months after being fertilized. The female cones grow to be 2.5 x 1.5 cm by the time the seeds are ripe. The winged seeds are released starting in late August and are dispersed for short distances by the wind.

The cones of black spruce don’t open fully and can remain on the tree for several years, so seeds from a single cone may not fall for more than a year after they were formed. The seeds can remain viable for many years. Overall seed production will vary greatly from year to year in any given region, but will tend to be very high once every 3-6 years. These infrequent bursts of seed production are common among most trees. It is an adaptation to ensure that, every once in a while, seed production far exceeds what the array of seed predators (squirrels, mice, birds, etc.) can eat. By “flooding the market” the trees ensure that some seeds will get a chance to grow and ultimately replace the parent trees.

Vegetative Reproduction

Black spruce occasionally reproduce asexually by a process called “layering”. Lower branches that are pressed down onto the ground may eventually form roots and the outermost branch tips will begin to grow upward to start a new trunk. In this way a single tree may eventually become a small grove of trunks. This process occurs mainly in sparse stands of spruce growing in poor soils, and is most common towards the northern end of the species range, at the tree line.

Ecological Significance

Manitoba doesn’t have that many species of trees to begin with (only 24, or thereabouts), so all our trees are vital for the role they play in creating forests. Over much of the central and northern part of our province, the black spruce is one of the most dominant tree species, so it is a major player in the creation of forest habitat for many other plant and animal species. It is the dominant tree species in lowlands throughout the boreal forest, providing food and shelter for animals such as the red squirrel (that eats the seeds from the cones), fisher and marten (that eat red squirrels), and birds like the boreal owl (which hunts for voles and shrews among the dense spruce groves) and the spruce grouse (which feeds on the buds of various conifers in winter). Because the seeds of black spruce often remain in the cones, they are an important food source for birds such as pine siskin, crossbills and pine grosbeak. Black spruce also forms important habitat for one of Manitoba’s rarest species, the woodland caribou.

Dangers and Diseases

Fire is a major factor in all forest types in Manitoba. The periodic droughts that afflict all parts of our province leave our forests open to wildfires. In the boreal forests, fire (most often from lightning strikes) is a regular player on the ecological stage and the plant and animal species that occur there are adapted to the drastic changes that fire brings. For tree species this means shorter overall life spans and emphasis on adaptations to quickly repopulate burned areas. Black spruce are easily damaged or killed by fire, but are well adapted to prosper in post-fire conditions. Fire helps to open remaining cones. Young seedlings do well in the open seed-bed prepared by the fire’s removal of the existing vegetation.

During the early 1990’s fire consumed more black spruce annually than did commercial logging, about 5 million cubic metres burned compared to about 3 million cubic metres harvested. But it should be remembered that forestry consumes trees at a fairly consistent rate, while fire losses vary wildly from year to year. (Source: Forestry Branch, Manitoba DNR, 5-Year Report to the Legislature 1997.)

Snow can have a major impact on the health and survival of a black spruce tree. A major drawback of being “evergreen”, is that snow will accumulate on the needle covered branches. Over the course of a winter, a tree may end up carrying hundreds of kilograms of snow on its branches. That’s enough weight to break branches. Strong winds can snap off the snow laden tops of trees. The weight of the snow can start a tree leaning, and a black spruce whose trunk has gone off vertical is doomed. In future winters the snow will pile up unevenly and put more and more force on the tree, eventually knocking it over.

Snow accumulation on a White Spruce.

Black spruce, like any plant, is subject to a variety of damaging pests and diseases. These can include:

  • Dwarf mistletoe (Arceuthobium pusillum), a parasitic plant that causes growth deformities and may lead to the death of trees.
  • Various fungi, mainly “rusts” (Genus: Chrysomyxa) can infect and damage all stages of the tree from seedling to mature tree, even affecting seed production.
  • Spruce budworm (Choristoneura fumiferana), the caterpillar of a small moth, eats the needles of this and other coniferous trees. Black spruce is not the favourite food of the budworm (they prefer balsam fir and white spruce), but in large infestations it can defoliate trees, resulting in slowed growth or even death.
  • Snowshoe hares (Lepus americanus) can damage seedlings and sapling trees. Although they are not a preferred food item for the hares, in years when the hare populations are high, they will eat almost anything, including the tender buds and branches of young black spruce.

Human Uses

Black spruce trees are harvested mainly for the pulp and paper industry (it is the most important pulp wood species in Canada), but occasionally for lumber (the yellowish coloured wood is both light weight and strong) and fuel wood (fire wood), and for use as Christmas trees. Keith Knowles with Forestry Branch, Manitoba Natural Resources, estimated that black spruce makes up about 20% of the current Christmas tree market in this province. As a kid, I don’t remember seeing much other than black spruce trees on lots in Winnipeg, but in latter decades Christmas tree farming has made different tree species available at prices to rival the wild harvested spruces, and black spruce seem to be harder to find in tree lots these days.

Here’s some more information I got from Keith, from Forestry’s most recent 5-Year Report to the Legislature (1997), on the economic significance of the black spruce.

  • “Black spruce comprises 31% of the available wood in Manitoba’s annual allowable cut, making it the most abundant species in the province, by volume. Because of its long wood fibers, black spruce is the preferred species of Repap Manitoba for kraft paper and Pine Falls for newsprint.”
  • “Black spruce cover type dominates 5.8 million ha of Manitoba’s Forest Zone. Intermediate-age trees comprise 127.9 million cubic metres in all cover types, mature 70.5 million cubic metres and over mature 10.1 million cubic metres.”
  • “Open zone Annual Allowance Cut (AAC) volume on provincial Crown Lands is 2.8 million cubic metres.” (That’s about 1.3% of the available black spruce wood per year, whereas fire consumes about 2.4% annually.)

A Last Word

Black spruce will always hold a special place in my heart, since it was central to so many of my Christmases past. But it is also one of Manitoba’s most important trees for tomorrow. It is a dominant species and the basis for wildlife habitat over much of our boreal forest region. Harvesting this tree provides jobs and helps support rural economies throughout our province. The ecological and economical importance of black spruce makes this a vital species for us all.

Thanks for learning about this Black Spruce trees! Bye for now!

Here’s some more winter articles you might enjoy:

Ruffed Grouse | Winterkill! | Makin’ Tracks!

Acknowledgments

The information in this article was drawn from a variety of sources, including the following:

Biology of Plants, 2nd Edition. 1976. By P.H. Raven, R.F. Evert and H. Curtis. Worth Publishers Inc., New York. ISBN 0-87901-054-1

Budd’s Flora of the Canadian Prairie Provinces. Revised by J. Looman and K. F. Best. 1987. Research Branch, Agriculture Canada Publication 1662.

Keith Knowles, with Forestry Branch, Manitoba Natural Resources provided some information from the Manitoba Forestry – 5 Year Report to the Legislature (1997).

Dan Bulloch, with Forestry Branch, Manitoba Natural Resources, provided some information and reviewed this article for accuracy.

St. Paul Field Office – Forest Resources Management and Forest Health Protection, USDA Forest Service, State and Private Forestry – Web site: http://willow.ncfes.umn.edu/ (An excellent source for forest information on the Web.)

Here are some other publications with useful information about the black spruce and other trees in Canada.

Identification Guide to the Trees of Canada. 1989. By J. Lauriault. National Museum of Natural Sciences. Pub. by Fitzhenry and Whiteside, Markham, Ont. ISBN 0-88902-654-9

Native Trees of Canada. 1990. By R.C. Hosie. Published by Fitzhenry and Whiteside Ltd. and Supply and Services Canada. ISBN 0-88902-572-4

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Colorado Blue Spruce grow from Kentucky north (but can do well in lower states such as New Mexico and Arizona if planted at elevations above 5,000 feet), as well as east of Idaho. Colorado Blue Spruce can handle a little bit of shade, but full sun is generally best.

PLANT IN RECORD TIME:
Watch how to plant evergreen seedling plugs faster and with less effort than any other type of “bare root” evergreen tree. With just a cordless drill, a garden cart or wheelbarrow, a 5 gallon bucket of water, and any old/dull/rusty 1 inch drill bit you have lying around, you can realistically plant one plug seedling per minute. Your back will thank us later 🙂

Colorado Blue Spruce plug seedlings: characteristics and info

• prefershardiness zones 3-6
• prefers full sun but does fine in partial shade when young
• mature height and spread: up to 75 ft high, 20 ft spread
• prefers sandy loamy soils, but does well in quite a wide range of soils
• Ohio State University info on Picea pungens Glauca
• Colorado Blue Spruce Sizes and Availability:
— Colorado Blue Spruce seedlings
— Colorado Blue Spruce transplants
— Colorado Blue Spruce plug seedlings
— Colorado Blue Spruce plug transplants
— Colorado Blue Spruce conservation grade plug transplants
• Comparable alternative species: Black Spruce, Black Hills Spruce, Meyers Spruce, Norway Spruce, Serbian Spruce and White Spruce. Confused about species? Check out our Evergreen Tree Buyers Guide

PACKAGING OPTIONS:
Plug seedlings are shipped in bundles, but we offer individual plastic packaging, eco-friendly packaging, cotton gift bag packaging and custom laser cut pendants for all sizes of plug seedlings and plug transplants, sold separately in matching quantities.

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