Norfolk Island Pine

Araucaria heterophylla

Family: Araucariaceae          Origin: Norfolk Island

People in climates where this tree can’t be grown outside (most notably in the US) grow what they think are Norfolk Island Pines in pots in their homes. Unfortunately, they’re usually mistaken. What is mostly available as a houseplant is actually the Cook Pine (Araucaria columnaris). But for the folks living in temperate, tropical areas, true Norfolk Island Pines grace suitable growing areas and are certainly sights to behold. Not technically a pine tree scientifically speaking, this tree’s overall appearance and form still lend it to look very pine-esque, especially when young.

This species is labeled as “vulnerable” and is a threatened species in its native island of Norfolk Island due to heavy harvesting in the past few hundred years. Protective measures have been taken to protect what’s left of this tree in its endemic homeland.

Arboriculture

Growth Form

Norfolk Island pines have a monopodial growth form, like most conifers. That is, they have a single trunk from which branches grow. The growth form is caused by strong apical dominance, growth occurring mainly towards the tip of the trunk.

As mentioned above, when this tree is young, it looks very much like a pine tree. Perfect triangle silhouette with evenly spaced branches, this tree looks great even when most other coastal trees that it shares its native home with are twisted and mangled by prevalent winds. They grow tall at maturity, around 65 metres when mature.

Trunk

Single thin trunks are vertical and tall, which made them valuable as masts for ships during early colonization of the island. Unfortunately, it was found they had a tendency to break, which lowered their value somewhat.

Foliage

Young trees have different shaped leaves from older trees. When young, the leaves are awl-shaped, about a centimeter long and overlap each other in whorls on stems. Older trees have incurved 5-10mm long needle like leaves. Thicker leaves that look like scales form in the upper crown of the tree.

Cones

Although Norfolk Island pine trees are not actually pine trees, they are still conifers. They bear woody cones similar to most pine trees in that they open out to spread their seeds while still on the tree.

Another misnomer, and one they also share with pine trees, is their cones being called male and female flowers. Conifers do not bear flowers. They branch off, on the phylogenic tree, specifically because they do not bear flowers (gymnosperms rather then angiosperms). There cones do, however, have male and female gender. Being on different trees, they are dieocious, though there are occasional trees which are not.

Fruits

Female flowers give way to squat globe-shaped cones that are about 12cm long and 14cm wide. They take 18 months to mature, and then they disintegrate and release edible seeds that look like nuts.

Management

Propagation

Many of these trees are started from clippings for pot culture, but this method also works for landscape plants. Take 2-3 inch new growth stem cuttings and root them in rooting medium. Keep them warm and moist until they form roots. They can also be started from seed.

Cultivation

While highly adaptable to different climates, this tree does especially well in areas where many other trees do not. Adapted to marine winds, this tree relies on the salty spray from ocean winds. It requires nutritionally lacking deep sand for soil. They require constant moisture without standing water. They don’t do well in very high winds, but do fine in consistent ocean breezes and some moderate winds.
In Brisbane, Norfolk Island pines are fine without added amendments to soil, but young trees do benefit from some added fertilizer to help new growth after a few weeks of being planted. Protect new seedlings for a year or two after transplant from high winds and sun that’s too direct. After establishing, this tree needs relatively no care.