Pines of the Castlemaine Botanical Gardens

Canary Island Pine (Pinus canariensis) is indigenous to higher altitudes, from 1,200m to 2,200m, in the Canary Islands being most prominent on Gran Canaria, Tenerife and La Palma. In Tenerife it forms the Corona Forestal, a crown around the island’s caldera. The species was named by botanist Robert Sweet (1783-1835), noted as author of Flora Australasica (1827-1828), one of the first books written exclusively about the Australian Flora.

Canary Island Pine is relict of tertiary flora. Its relatives are mostly found further east including Himalayas and Sumatra. It is one of the most fire tolerant pines with thick red-brown and buff bark that insulates the tree. After fire it frequently produces blue epicormic needles.

Importantly, the pine contributes significantly to local ground water. Rainfall on this high ground is immensely variable and may be as much as 2 metres but may receive as little as 50cm a year. Rain clouds and mist condense on the pines’ 28cm long needles and water weighs them down. Surface tension holds water to the leaf surface where it runs to the leaf tip before dropping to the ground to contribute to the water table increasing rainfall from 50cms to 200cms!

Leaves may last between 1.5 and 3 years before falling to the ground where to form a thick mulch limiting growth. Local Rockrose (Cistus symphytifolius) and Tree Lucerne (Chamaecytisus proliferus), a serious environmental weed in south-eastern Australia, are most prevalent.

Traditionally, local growers collect the decaying needles as fertiliser on their terraced allotments and foliage was also traditionally used to pack bananas. Both removed nutrients from the forest but also reduced combustible leaf litter reducing the fire risk.

White Bark pine (Pinus albicaulis) is a dominant high-altitude pine through much of the Rockies from Alberta and British Columbia in Canada through Washington and Oregon, Montana, Idaho and Wyoming to eastern California and Nevada in USA.

Seeds of White Bark pine are not released from their cone and depend upon the work of Clark’s nutcracker to free them. These birds collect seeds, they carry up to 150 seeds within their facial pouch, which they distribute in caches of 1-15 approximately 2 cm deep in moist soils. A bird may cache 90,000 seeds each year over a vast area, but it can still identify hiding places in winter when covered by a metre of snow!

Not all caches are eaten and one way of identifying White Bark Pine is that it germinates as a group of four or five seeds, left-overs from a Clark’s nutcracker cache!

Recently this pine has been described as endangered though its range is enormous largely because of Blister Rust Disease and Mountain Pine Beetle, two major threats, prospering because of warmer winter temperatures from climate change. Add to this the control of wild-fire burns and the population of this tree, vital to the diet of Clark nutcracker, Black and Grizzly bears, Red squirrels and other mammals, is in rapid decline as too the population of Clark’s nutcracker.

The pine and the nutcracker are a remarkable example of mutualism, each benefits from the other, but their joint decline underlines the fragility of many of our ecosystems and the risk of loss we face in a climate change world.

Monterey Pine (Pinus radiata) is familiar to Victorians in forestry plantations and a significant weed in native bushland. Our climate suits its growth.

Monterey Pine is indigenous to restricted areas at elevations of 30-400 metres in the fog belt of coastal California, in San Mateo and Santa Cruz, San Luis Obispo and Monterey counties. In each location pressures of agriculture and development have reduced its numbers and distribution but recent population decline is largely the result of an introduced fungal disease from south-eastern USA, pitch canker. Infection with this fungus allows bark beetles to transmit it to other trees; the result is that 80-90% of trees in native stands are infected.

Importantly, should this fungus be transported to plantations in New Zealand and Australia the economic impact would be catastrophic!

The lessons are twofold, sound biosecurity is vital to the well-being of our flora and economy, and the benefits of having populations of rare trees within Botanic Gardens collections is that they may provide a source of seed for re-introduction in extreme circumstances.

Named for the ancient city of northern Syria, Aleppo pine (Pinus halepensis) is more common further west in Morocco, Algeria, Tunisia, southern Spain and France, Italy and Greece. There are small native populations in southern Turkey, Syria, Israel and Jordan.

Widely grown in the Mediterranean as an outstanding timber tree it is also valued by native populations in different areas of the Mediterranean as a food source, its seeds being valued in Malta and Tunisia for desserts and, most famously, in Greece to flavour the wine, retsina.

Historically, porous earthenware amphorae of the Greeks and Romans were treated with resin from Aleppo Pine to seal them when liquids including wines were stored. The wines kept longer but assumed a resinous flavour. In the western Mediterranean wooden barrels were adopted but in the Byzantine east, the resinous wines from amphorae remained popular. Today, small pieces of resin from Aleppo pine are added to the fermenting wine at rates chosen by the oenologist to produce retsina.

Aleppo Pine is invasive in many areas though it has also been widely planted as an ornamental tree, notably in Israel where its use to create parks has resulted in loss of native garrigue shrubland.

The characteristic mature canopy of Umbrella or Stone Pine (Pinus pinea) is unmistakeable. Cultivated for so long that its original distribution is difficult to identify, Stone Pine is found throughout the Mediterranean basin, notably along ancient trade routes. It would appear to have originated in the southern Iberian Peninsula which still boasts 75% of Mediterranean forest area.

Distributed for its food value, it has been harvested for at least half a million years being transported to Egypt, described by Theophrastus (c372-287 BCE) and recorded in the second century AD when sixteen pine cones, cakes and palm branches were supplied to a district governor in Greece for sacrifice to the river-god Nilos.

Encouraging its distribution more widely, no doubt, was its widespread acceptance as an aphrodisiac. Galenos, a Greek physician of the 2nd century AD suggests a mixture of pine nuts, almonds and honey taken before bed on three consecutive nights can increase sexual potency. Apicius, a well-recognised Roman gourmand whose recipes were used into the Middle Ages and who, amongst other delicacies, advocated walnut stuffed dormouse, suggested a mix of pine nuts, cooked onions, white mustard and pepper for the same purpose.

Pine nut production varies in cycles of 2-6 years with cones being harvested by hand; a collector gathers 400-600 cones a day. A hundred kilograms of cones produce 15-22kgs of nuts released by drying the cones in the sun, the empty cones having value as fuel. As would be expected for so large a nut, the seed is naturally spread by a bird, in this case Iberian Magpie.

Mexico is home to between 43 and 51 pine species meaning that approximately half of the world’s pines call Mexico home. Many grow in association with oaks. Pines in Mexico occupy a range of climate types with some in subtropical zones, some in cool climatic zone but the vast majority in temperate environments.

Mexican Weeping Pine (Pinus patula) is amongst the latter group and with its straight broad bole has been introduced as a timber tree in many parts of the world. In its native habitat it enjoys between 750 and 2000mm per annum though most of this rain occurs in summer!

Unfortunately, it has proved weedy in many areas where introduced and is noted for invading areas of native bushland to the detriment of ecological values.

California’s native Foothill Pine (Pinus sabiniana) is characteristic of dry lowland hills around the state’s Central Valley where commonly found with four oak species, California Blue oak (Quercus douglasii), Canyon Live oak (Q.chrysolepis), Interior Live oak (Q.wisilzeni) and Valley oak (Q.lobata) with lower growing California buckeye (Aesculus californica), Western Redbud (Cercis occidentalis) and California Scrub Oak (Quercus berberidifolia). One of California’s largest ecosystems typifies a Mediterranean environment with rainfall from 76 to 1000mm annually, predominantly in winter and spring, and maximum summer temperatures around 41 degrees centigrade. Foothill Pine grows rapidly to 20 metres, is short-lived producing large quantities of seed, suggesting it has evolved with fire as part of its ecology.

First collected and described by David Douglas (1799-1834) in southern Oregon in 1826 on his second collecting trip he lost his initial collection, collecting it again in 1831 on his third and final collecting trip near Monterey. Named for Joseph Sabine (1770-1837), secretary of the Royal Horticultural Society, under whose patronage Douglas was sent to collect in north America.
With long, drooping, dull blue-green leaves in bundles of three and large pendulous cones to 25cms with upcurved claws at their tips to 2cms, this is a readily identified pine. It has the largest seeds of all pines spread by Steller’s jay.

The values of Sabine pine to earlier explorers in California was described by the great Californian natural historian John Muir (1838-1914) who wrote:

“In general appearance this tree looks more like a palm than a pine. The cones are about six or seven inches long, about five in diameter, very heavy and last long after they fall, so that the ground beneath the trees is covered with them. They make fine resiny, light-giving camp-fires, next to Indian corn the most beautiful fuel I’ve ever seen. The nuts…..are gathered by Digger Indians for food. They are about as large and hard-shelled as hazelnuts, --food and fire fit for the gods from the same fruit”.

Lone pine or Gallipoli pine, more widely known as Calabrian pine (Pinus brutia), is not native to Calabria, known to Romans as Brutia. More commonly known as Turkish pine, a better description of its native distribution it is distributed through eastern Greece, Turkey, Iran, Iraq and Syria and more broadly in low altitude, 0-1,525m, eastern Mediterranean locations, mostly in coastal environments.

Turkish pine was distributed beyond its native distribution early in history for its production of pine honey, honey-dew gathered by bees from a sap sucking insect.

The species holds an iconic place in Australian culture. A single tree on Gallipoli Ridge remained after Turkish forces had removed foliage and branches from other trees to build their trenches prior to the Battle of Lone Pine, August 1915. Australian forces used this single tree for target practice and it was obliterated during the battle.

Seeds from this tree were carried home to Australia following the campaign, successfully germinated at Grasmere near Warrnambool, western Victoria, the seedlings being planted at Wattle Park and the Shrine of Remembrance, Melbourne, the Soldiers Memorial Hall, near Terang and the Warrnambool Botanic Gardens.

Natural distribution of seed of Turkish pine uses a mixture of birds and wind. Seed is usually released 1-2 years after fertilisation when cones have been softened by rain. On occasion the seeds are unable to escape the wet cone when the Kniper’s nuthatch bird steps in and distributes seed.

Scots Pine (Pinus sylvestris) is one of the dominant pines of the northern hemisphere and, after Common Juniper (Juniperus communis), the most widely distributed conifer in the world. Its distribution extends across western Europe to Siberia, the Caucasus and Anatolia including inside the Arctic Circle. Readily identifiable from other pines by its short, dark green needles in twos, its salmon bark, especially notable in the upper trunk and its small cones.

In Britain, Scots Pine retreated in the face of the last Ice Age before progressively re-colonising as the ice sheet retreated. Present in southern England 9,000 years ago, it reached the Lake District 8,500 years ago and Scotland about 8,000 years ago where it formed a significant part of the Caledonian Forest of the Scottish Highlands. Today, as a result of overcutting for timber, fire, over-grazing by sheep and deer and clearance to deter wolves, only 1% of the 1,500,000 hectares of pine remains.

Out competed by numerous broad leaf trees on fertile soils, it is restricted to nutrient poor sandy soils, rocky outcrops and peat bog with a natural distribution range from sea level to 1,000 metres in its northern distribution to 1,200 metres up to 2,600 metres to the south. It has been selectively felled for timber often sold as “deal”, an ancient measure of timber volume.

The most widely distributed of America’s pines, Western Yellow Pine (Pinus ponderosa) was collected by David Douglas in 1826. Named ‘ponderosa’ for the heavy weight of its wood, as might be expected from a tree with so large a distribution, from southern British Columbia in the north down the American west coast as far as northern Mexico in the south, there is significant variation in plant form leading to identification of five subspecies.

Typically, Western Yellow Pine has long needles to 200mm, mostly in bunches of three and is one of the tallest growing pines reaching 70 metres. Bark on Western Yellow Pine is useful in identification, mature trees having yellow to orange-red bark in large plates with black crevices between.

Early images of Western Yellow Pine forest show open country with large trees emerging from grassland, a circumstance maintained by regular low intensity fires on a 5 to 10 year cycle. Recent research shows accumulation of needles on the forest floor and frequent lightning strikes may result in low intensity fires as frequently as a three-year interval. This prevents the growth of competitive species such as scrub oak and low shrubs while thick, insulating bark layer of the mature Western Yellow Pines ensures they are able to survive as too do a proportion of their seedlings. As an example of man’s interference in natural ecologies, prevention of these fires leads to a build-up in shade tolerant conifers and shrubs as well as layers of pine needles. Fires are now more intense and destructive, killing the mature forest areas and causing more extensive damage.

Native to the western Mediterranean including Portugal, Spain, western France, Corsica and Morocco, Maritime Pine (Pinus pinaster) has been planted widely for timber, resin and turpentine. Maritime Pine makes up the largest man-made forest in the world, 900,000 hectares at Les Landes on the west coast of France planted under the direction of Napoleon III from 1857 not for timber but to prevent drift of sand dunes onto agricultural lands.

Introduction of Maritime Pine into South Africa has proven to be a classic case of an invasive weed with significant impact upon the unique finbos vegetation. Effects of invasion of Maritime Pine includes increased extinction amongst native plants and modification to water flow within drainage systems. The pines take up more water than native plants resulting in a decline by as much as 55% in water flow, with resulting impact on native vegetation downstream in areas with no pines. Thinning of pines results in water flow increasing.

Additionally, Maritime Pine withstands high intensity fires that have a serious impact on native plants, producing light seeds that germinate quickly producing 25 seedlings per square metre, a density that decreases over time from intra-specific competition. Rapid seedling growth outpaces many fynbos native plants and their light seed can be spread widely on the heated wind currents. Many fynbos seeds are heavier and distributed by vertebrates, putting these species at a significant disadvantage compared with Maritime pine which easily seeds into even inaccessible areas. Additionally, the pine gives off chemicals, oleoresins, that inhibit germination and growth of competing species, a process called allelopathy giving it further advantages. Add to that the absence of pests that might control its growth and this is the classic invasive weed.

Biological control is being investigated with consideration being given to weevils and mites that will feed on weed tissue but these need to be proven to be host-specific and have a sufficiently high reproductive rate.