Posted April 15, 2008 by heather hartman in Species Specific

Pinus banksiana

Jack Pine bonsai and photograph by Jerry Vlcek

Jack Pine bonsai and photograph by Jerry Vlcek

Scientific Name: Pinus banksiana
Common Names: Jack Pine, Eastern Jack Pine, Black Jack Pine, Black Pine, Jerry Pine, Prince’s Pine, Princess Pine, Bank’s Pine, Banksian Pine, Hudson Bay Pine, Gray Pine (usually refers to P. sabineana), Northern Scrub Pine, Scrub Pine (usually refers to P. virginiana), Pin gris
Cultivars: “Broom” Smaller cultivar, growing to only 5 feet (1.6M).Irregular, curving habit.
“Chippewa” Dwarf cultivar, developed in the 1970’s. Globular habit.
“Manomet” Dwarf cultivar with irregular, globular habit.
“Schoodic” Dwarf cultivar, slow growing. Creeping, prostate habit. Dark green foliage.
“Uncle Fogy” Pendulous cultivar, usually growing 10f(2.3M) in the landscape.

History: The species was named for Sir Joseph Banks (1743-1820), a British naturalist and botanist on Cook’s first great voyage (1768-1771). All told, some 75 species are named after him.

Prior to European settlement, the Jack pine was a common tree in swaths of the Northern US and Southern Canada. It was found most commonly in some of the hottest, driest summer sites of those areas; sandy glacial plains and hills. Occasional lightening storms would bring fire sweeping down those dry areas, leaving behind nothing but blackened desolation. Native Americans, either accidentally or intentionally, also caused fires in the jack pine. This desolation was only temporary however. Sometimes within weeks, after the Jack pine seeds had fluttered to the ground, the area would be covered with a green haze of new growth. This process would repeat every thirty to a hundred years, and Jack pines would continue to dominate these fire prone areas.

After European settlement, many areas where white and red pines grew near the jack pine plains were stripped of the more desirable pines. Large areas of slashed and clear cut forests were left after logging, leaving an opening for the expansion of the Jack pine’s range. However, the creation of the Department of Conservation, and the fight to bring all forest fires under control in the early 1900’s, brought the Jack pine community into decline, confining it back to ranges smaller than even the previous areas. As jack pines need full sun and fire to grow, areas where fire was completely controlled led the eventual take over of more shade tolerant species. As the Jack pine is a tree necessary for the survival of several other species (including the endangered Kirtland’s warbler), controlled burns are now allowed in those areas, to keep the Jack pine ecosystem at healthy levels.

Anatomy: Jack pines are a native North American conifer, ranging from Canada to the northern parts of the United States. An upright, broad and irregular habit, jack pines range from 3-80ft (1-m) tall in the landscape, though can at times grow up to 100ft (33m) tall. They tolerate a range of poor soils, often found on sandy or rocky hillsides that little else can grow on; though will have a naturally stunted habit. Jack pines in the landscape usually start to show signs of decline around 75 years, though the species can live over 200 years. In the absence of fire, a necessary part of their reproductive cycle, jack pines will die out, replaced by longer lived species (like Red Pines, P. resinosa) or species that are more shade tolerant (Like firs and spruces). They are often seen in single species stands, all around the same age, as they are one of the first species to move in after a fire, and can grow in notoriously poor soil, preparing the way for other species as needle detritus creates better soil conditions over the years. In the first 20 years of life, Jack pines are one of the fastest growing conifers.

Jack pines develop a tap root as a seedling, and maintain it through maturity. The tap root can grow to depths of more than ten feet, though longer, lateral roots in the top 18 inches of the soil make up the bulk of the root system.

The Jack Pine can hybridize easily with the Lodgepole Pine (P. contorta), a closely related species.

R.A. Howard @ USDA-NRCS PLANTS Database

R.A. Howard @ USDA-NRCS PLANTS Database

Foliage: The needles are in fascicles(pairs) of two, twisted, ranging from 1-2inch (2.5-5cm) long, and can reduce further with bonsai techniques. Foliage colour ranges from yellow-green to dark green.

Stem and Trunk: Medium thick bark, growing flaky and cracked as time goes by. Branches have a naturally horizontal, sometimes scraggly, growth habit.

Photograph from Wikimedia, image is in the public domain

Photograph from Wikimedia, image is in the public domain

Flowers/Fruit/Seeds: Jack pine are a monoecious (having both male and female parts in different flowers on the same plant) species. Ovulate (female) cones are usually borne on primary and secondary branches in the upper tree crown and staminate (male) cones are usually borne on tertiary branches lower in the crown. Female cones are modified long shoots and male cones are modified dwarf shoots. Male cone primordia are initiated in mid-summer, while female cone primordial do not initiate until later summer, growing until September, then go dormant until spring. Pollen shedding (anthesis) usually occurs in late spring or early summer but is highly dependent on the weather. Fertilization occurs 13 months after pollination. Cones mature in late summer or early fall, about 2 years after their growth begins. The cones of the jack pine are 1.5-2 in (3-5cm) long. The scales of the cones have small, fragile prickles that usually wears off before maturity, leaving the cones smooth. The cones point forward along the branch, sometimes curling around it, which is unusual in pines. Cones are serotinous (which means they open when exposed to fire or high heat), and are sealed shut by resin. Jack pines are fire-adapted to stand-replacing fires, with the cones remaining closed for many years, until a natural forest fire kills the mature trees and opens the cones to release the seeds. Some trees in the southern parts of the range have nonserotinous cones, and high temperatures and dry summers with prolonged temperatures of over 80F (25C) can also open these cones. Jack pines usually take between five to ten years to reach maturity and start creating cones. Seeds remain viable in closed cones for years, but viability decreases over time. Up to 50% of 20-year-old seeds may be viable. The winged seeds are the smallest of the native pines and are typically dispersed by gravity and wind.

Hardiness: Zones 3-7 in the landscape. Jack pines require a certain minimum temperature, and warmer winters can prove a problem for them.

Light: Full Sun. Jack pines are not shade tolerant at all.

Soil: Ensure excellent drainage. Prefers neutral to slightly acidic soil. Try a mix that includes up to 50% sand. Boon Manakitivipart recommends a conifer mix of one part akadama, one part pumice, one part lava rock, plus 1/2 cup each of horticultural charcoal and decomposted granite to each 5 US gallons of the above mentioned mix, a mixture which David Johnson of the Toronto Bonsai society prefers for his Jack Pines.

Watering: Thoroughly. Do not keep boggy, and allow to almost dry between waterings. In the landscape, jack pines are extremely drought resistant, but need to be watched closed in bonsai cultivation.

Fertilizer: Balanced feed through the growing season, into the fall. Taper off in autumn. Stop fertilizing for the winter. Try an acidic fertilizer for best results.

Pests and Diseases: Redheaded Pine Sawfly (Neodiprion lecontei) and Jack Pine Budworm (Choristoneura pinus), though rare in bonsai cultivation, as both thrive on groves of older jack pines, rather than individual trees. Rust. Aphids, borers, and weevils.

Repotting: Every other year at most for younger trees, up to every five years. New root growth can be very slow. Do not remove all of the old soil, as jack pines require a beneficial bacteria called mycorrhizal that lives in the soil. Root prune lightly, especially on collected trees.

Pruning and Styling: Seriously insult a Jack pine only once a year at most. If repotting has been done, avoiding pruning until the following year. Insults can be anything that will weaken the tree; repotting, serious foliage reduction, trunk wounding, pruning, decandling or major bud removal, heavy wiring, etc. Think in terms of years, rather than months. Do one round of pruning, and then allow to recover for the year, even if the tree looks to be doing well, rather than a series of pruning over the course of a couple months. Allow a lengthy period of unchecked growth for recovery. Do not insult the tree anew until vigorous growth is shown. Watch new candles to gauge a tree’s vigor, including colour (should be a light, bright green), shape, and length, as well as the number and size of new buds.

Avoid concave cuts. It can disrupt the flow of sap in the area, and lead to dieback higher up the trunk. Leave a stub where the branch was, and either jin, or allow to dry out for a season, and then cut flush to the trunk, allowing the tree to find a new path for the resin. Cuts can take a long time to heal.

There is an area at the end of branches that becomes vacated after the male flower drops off in the spring. This area sometimes produces new buds, so don’t prune into this area if you want more buds there.

Remove needles growing on the tops, or underside of the branches. Remove weak buds where two or more buds are clustered, leaving the strongest. Start on the weakest parts of the tree, allowing several weeks of growth before repeating on stronger, more vigorous areas.

Healthy jack pines can backbud to old wood by needle pruning, or partially removing a branch.

Wire: Only wire healthy and vigorously growing trees. Young branches can set in as little as a year, larger, older branches needing more time. Use raffia to bend thicker, stiffer branches.

Leaf Reduction: Needle reduction through pot culture and candling. Withholding fertilizer during early spring, until needles harden off can help reduce size. Watch for the needles to change colours from light to dark green, usually sometime in May.

Jin/Shari: Suitable to deadwood styles.

Styles and Forms: Most forms except informal upright and broom. Jack pines are not well suited for very formal stylings. Let the naturally wild nature of the tree guide you.

Notes on Collected Jack Pines: Exercise particular patience. Jerry Vlcek recommends keeping as much original soil as possible, surrounding with bonsai soil in the pot or grow box. Once a tree recovers its vigor (minimum of a year, quite possibly two or three years), root pruning can be done, but again, do not remove the old soil. Slowly work new soil into the old soil as it decomposes, over successive repottings (every other year). Resist the urge to prune at the same time as collecting unless strictly necessary. Boon Manakitivipart recommends removing 1/3 to ½ of the field soil at one time, each time the tree is repotted. Allow the tree time to adjust to the new soil, and avoid candling on off years, as the switch from soils is more drastic in this fashion, and the tree needs to focus on healthy growth, rather than on needle size and the internode spacing. Focus on recovery and the changing out of soils, followed by branch pruning for shape, and only then working on ramifications and needle length when the larger insults have been survived.

Seeds: Plant in sand/peat mixture, less than a half inch (1.3cm) beneath the soil, once temperatures have reached 65F (17C). Keep seeds in full sun to partial shade and keep evenly moist. They can germinate in as little as 15 days, to 60 days. If they have not germinated by that time, dormancy may need to be broken. Leave seed trays outside through the following winter, or bring indoors and store in the refrigerator until spring and try again.
Cuttings: Cuttings from young trees can root, but rooting ability decreases drastically with tree age. Cuttings from seedlings of a year old or less have the greatest chance of rooting. Use rooting hormone to increase chances.
Other: Grafting

Other Facts and Trivia: Jack pine seeds are often found in small bonsai kits at the mall or bookstore. These seeds are seldom viable, due to long storage times, and even those that could germinate often don’t, due to inaccurate care information.

Native Americans and early European settlers to Canada and the Northern United states considered jack pines evil, as no crops could grow in areas where they had been cleared. As these pines so frequently grew in poor, sandy soil however, it’s no wonder. The French Canadian lumberjacks believed that a woman must keep at least 10 feet away from this tree, lest they become sterile. Infertility and miscarriages in both humans and animals were often blamed on a grove of jack pines in the vicinity.

Caribou feed on the lichen that grows on the tree, moose, caribou, snowshoe hares, and deer feed on the branches, rodents and birds eat the seeds. Native Americans used the bark for tea, the roots for sewing, the pitch for medicine and sealant, and the male cones have long been eaten boiled, roasted, fried, or pickled.

Jack Pines in Nature:

Jack Pine showing a typical twisted form on a ground level branch. Photograph by Will Heath

Jack Pine showing a typical twisted form on a ground level branch. Photograph by Will Heath

Mature Jack Pine bark Photograph by Will Heath

Mature Jack Pine bark Photograph by Will Heath

Ethnobotany of the Ojibwe – Huron Smith
Native American Ethobotany – Daniel Moerman
Botanica – North America – Marjorie Harris
Trees and Shrubs Ernie Wasson, Tony Rodd, 2004
Trees of the World Tony Russel, Catherine Cutler, Martin Walters, 2006
Jack Pine: http://www.na.fs.fed.us/pubs/silvics_ma … ksiana.htm
Jack Pine Ecosystem: http://www.michigan.gov/dnr/0,1607,7-15 … –,00.html
Jack Pine Project and Interview: http://torontobonsai.org/Archives/Research/index.htm
Rook Jack Pine Sheet: http://www.rook.org/earl/bwca/nature/tr … sbank.html
Wiki Jack Pine sheet: http://en.wikipedia.org/wiki/Jack_pine

heather hartman