Jack Pine

It may not be majestic, but it’s PEI’s rarest native conifer and has an adaptation unlike any of our other trees. Meet Jack Pine (Pinus banksiana).

If you say ‘pine’ on the Island, chances are you mean White Pine (Pinus strobus), a flagship of our early forests and mainstay of the lumber industry. Red Pine (P. resinosa) is also native and was widely planted in the mid- to late 20^th century. But you might not know about Jack Pine.

While White and Red Pines can reach heights of 30 metres (100 feet) or more, Jack Pine rarely tops half that; the ones I see on the Island are often smaller, as shown here (main photo). It’s not hard to see why ‘Scrub Pine’ is another common name for this tree.

In addition to size, Jack Pine is easily differentiated from the long-needled White and Red Pines by its short needles in bundles of two (top right photo). It also has distinctive cones that curl or bend at the tip (middle right photo). Some of those cones are more than meet the eye.

Jack Pine is a fire-adapted species. While the tree itself isn’t flame-resistant, some of its cones are ‘serotinous’: sealed by resin which prevents the seeds from dispersing until that resin is melted by fire. This not only helps the species survive, it also allows seeds to be dispersed into a landscape where they have the advantages of full sun and no competition from other plants. A stand of mature Jack Pine can have as many as five million seeds per hectare (two million per acre) held in those serotinous cones.

That’s a handy adaptation, but what if there’s no fire? In some cases, direct sunlight and very hot weather can do the trick, though serotinous cones often need temperatures above 45C (115F) for the resin to melt. A better approach is to hedge your bets: produce some cones that aren’t sealed and open as soon as they mature (bottom right photo). Jack Pine is found from the Northwest Territories all the way down to Pennsylvania, and trees in the less-fire-prone south and east have far fewer serotinous cones than those in the Boreal forest.

Jack Pine prefers full sun and is often found on poor, sandy soils – likely because it finds less competition there, rather than truly preferring those sites. Like all Pines, Jack Pine forms mutually-beneficial relationships with fungi in the soil which is an added benefit on nutrient-poor sites.

This is a tree that was likely never very common on the Island. Jack Pine is present in a few locations in all three counties today, but I find it most often in West Prince, especially on inland sand deposits that formed following the last glaciation. (It’s not very salt tolerant and I’ve never found it on coastal dunes).

Artist Tom Thompson may have made it famous, but Jack Pine is an interesting part of PEI Untamed!