They are the most distinctive and unforgettable trees in Southern California gardens and landscapes.  Unlike palm trees, which also have an exotic look, there are not so many of them as to become boring.  The first time you see one, your jaw drops in amazement and you have to go up close and touch the foliage since this is a tree that does not look real.

I am talking about Norfolk Island pine (Araucaria heterophylla).  Indigenous to an island 900 miles east of Australia, the trees are valuable in their habitat both for their nutritious seeds, which are comparable to pine nuts, and their wood.  Yet the population of these trees has dwindled considerably and, like other Aruacaria species, Norfolk Island pines are considered biological relics, meaning that where there were once forests of them, only scattered clumps remain.

Alas, even if you have a Norfolk Island pine, you will probably never taste its seeds/nuts.  The reason for this is that it is a dioecious tree, meaning that there are both male and female trees, and even if you have a female — the seed producing sex — you will only get seeds if there is a male in the vicinity that can pollinate the female.  Although they do not fit the precise definition of pine trees, Norfolk Island pines and their cousins — monkey-puzzle tree and bunya-bunya — in the manner of true pines and other conifers, are wind-pollinated.

Interestingly enough, I notice that no large local nursery grows these trees.  With monkey-puzzle (Araucaria aruacana) and bunya-bunya (Araucaria bidwillii), the reason could be safety issues.  The foliage of monkey-puzzle is razor sharp and the cones that eventually form on bunya-bunya may be as large as one foot in diameter and weigh as much as forty pounds.  You can spot this tree in the Pierce College Arboretum but want to avoid standing underneath it unless you are wearing a hardhat and, even then, you might not be completely safe.

Norfolk Island pine, while not at all dangerous, is a slow grower with unpredictable symmetry and these factors may be responsible for its becoming something of a specialty item for indoor use, almost like an orchid.  Walking north on Hazeltine Avenue toward Fashion Square in Sherman Oaks, for example, two Norfolk Island pines come into view. One is on the east side of the street, and one is on the west. Each leans longingly toward the other, like star-crossed lovers who will never wed. This tendency to lean can be a major problem with the Norfolk Island pine. Its foliage also burns when exposed to full-day summer sun or excessive wind.   Because of its slow growth rate, however, Norfolk Island pine does makes an excellent container plant.

In fact, the inspiration for this column came from Marlene de Valera, who gardens in Simi Valley, and acquired two of these trees in five gallon containers last month.  She asked by way of e-mail whether “they need sun or will the covered patio work.”  Although you do see these trees growing in full sun, they really are better suited in our area to partial sun.  A covered patio is an excellent place to grow them, and they perform well indoors, too.  Make sure to rotate them, like any potted plant, 90 degrees each week.  That way, all sides receive equal sun exposure and you will never see them lean in one direction.

And although it is famously sensitive to too much heat or cold, I received the following response from Anne Zedalis of Burbank when I wrote about Norfolk Island pines several years ago:  “Five years ago I bought this tiny Norfolk Island pine for the holidays. It cost $2 and was about six inches high. It grew like crazy, so I planted it into larger and larger pots. When it was three years old I put it in the ground and it is now almost thirty feet high with enormous wide branches. It’s incredible to say the least. I have not found it to be sensitive to our heat and cold. It may be subtropical, but it grows like crazy here in Burbank. It’s like Jack and the Beanstalk to me. Incredible. I have hummingbird feeders in it as the birds enjoy sitting on its long branches.”

All Auracaria species may grow up to 100 feet tall in California, while in their habitat — which includes, Australia, New Guinea, Argentina, and Brazil — they may reach 250 feet and live for a hundred and fifty years.  They are considered among the most ancient trees and it has been suggested that those long-necked, herbivorous dinosaurs, some of which reached 170 feet in length, evolved along with these trees which were a major source of sustenance for them.

Getting back to care indoors, attention to humidity is important, especially during winter when indoor air is driest, since they are tropical species.  You can either keep a humidifier in the room where your tree is located or place your tree on a tray of pebbles with water, making sure that the water stays beneath the pot since the bottom of the pot must be kept dry to avoid fungus issues.   Plenty of light, but not an overdose of it, is also important.  This means that your Araucarias can receive direct light for several hours a day or bright, ambient (indirect) light for several hours more.  Do not fertilize now but you should do so in spring and summer with a low concentration water-soluble product.  Browning of lower branches is not unusual but browning of higher branches may be attributed to too much or too little water or to low humidity.

Even though you will not be fertilizing for a while, kept abreast of your plants’ watering needs by checking the soil at a one each depth.  When this soil starts to dry, it’s time to soak your plant until water goes down through the holes in the container.  Again, make sure the bottom of your container does not sit in water.

In a study conducted by NASA a number of years ago, it was found than Norfolk Island pines purified the air indoors by removing VOC’s (volatile organic compounds).  VOC’s are present throughout your home, being constantly released by beauty products, dry-cleaned clothes, paint,permanent markers, glue, and cleaning products of all types.  The more Norfolk Island pines you can squeeze into your home, the more healthy the air you breathe will become.

Tip of the Week:  It’s the most spectacular winter plant growing in our area, but you probably need to drive to or live in Thousand Oaks, and points west, to find it.  The plant is called flame vine (Pyrostegia venusta).  It’s evergreen and climbs up to 40 feet.  Flame vine is one of a small group of plants whose flowers make a more stunning impact when they are closed than when they are open.  The most apt description of flame vine’s flower show would be “flaming orange fireworks finale.”  If you want to try growing it in the Valley, I would train it up a trellis against a wall that faces east so that, in the event of a frost, it would quickly benefit from morning sun that would warm up and resuscitate any of its cells that had frozen during the night.