| General Description | This highland rainforest tree comes from an ancient family of conifer trees (Araucariaceae, globally common in the Cretaceous and Jurassic periods), and can grow up to 50 m tall and 2 m in diameter. Agathis atropurpurea also known as the Blue Kauri today, is native to and only found in Queensland, Australia; making this species very
vulnerable to extinction and a good example of a relictual species. This specimen is long-lived (600 years or more) and very slow growing. Its conservation status is ‘Near Threatened’, and it was placed on the Red List of endangered species as a precaution. It does not quite meet the criteria to be deemed a threatened species. |
| ID Characteristic | Easy identification points would be the exfoliating bark and the irregular patches of mottled purple, left behind on the bark’s surface. The bright green globe-like female cones are also a famous attribute of this tree, resembling a tightly wound spool of string. The bright lush green leaves are another identifying factor as most wouldn't think of them as coniferous foliage. The resin (Manila Copal) is white and viscous and has a citrus fragrance. |
| Shape | Young tree crowns grow in a conical shape, but as they age the crown will look more globular. In older specimens, there is little to no branching occurring on the lower trunk and vegetative matter is mainly confined to the upper canopy of the tree. |
| Landscape | The Blue Kauri is used more as a specimen plant in a botanical garden to be viewed for educational purposes, rather than for landscape use. This species is restricted to only the wild coastal mountainous regions of North East Queensland. |
| Propagation | Seed or woody cuttings are the main propagation techniques when cultivating this species. When producing cuttings you must be careful where you make your incision, as taking from a top node (as opposed to a lower node) produces larger shoots. For successful rooting, keep cuttings in a moist, humid environment. Experiments from a study done by
Oxford University indicated that seedlings transplanted and grown in dryer climates (Malaysia) performed poorly. For seed propagation, there is no specific treatment required before sewing; however, the seed does not respond well to desiccation. Must not store the seed for longer than 2 months. When sewing, make sure the seed is 66% covered by soil with the wing facing upward. Germination should take up to 6 days; again making sure the growing climate is shaded, moist and humid. |
| Cultivation | This specimen thrives in a rainforest environment, so it prefers full sun and very humid climates. The Blue Kauri requires deep, rich and moist soils. It has limited frost hardiness as it is confined to growing regions which never encounter freezing temperatures. The only reason for pruning would be to limit the size or to keep form/shape. The main way to propagate is from seed or hardwood cuttings. |
| Pests | Known pests are few and far between. However, studies of ancient fossilized specimens suggest these trees are prone to damage by leaf mines, galls, rust fungi and other types of chewing damage caused by insects. Comparable damage is still found on modern specimens. Invasive species and climate change pose a greater threat to this species.
Millions of years ago, the Araucariaceae family grew all over the globe, but as the Australasian continent drifted into a hotter and dryer location, this species had to migrate to wetter coastal regions. With the modern threat of climate change, these species might not have anywhere else to seek refuge. |
| Notable Specimens | There are no notable specimens recorded as being extraordinary. This is a wild, rainforest-dwelling, ancient pine that can be seen in highland coastal regions in the bush of Queensland Australia. Some specimens are protected and on display in national parks and botanical gardens (e.g., The Australian Botanic Garden Mount Annan). |
| Habitat | This ancient specimen grows in the highland coastal regions of North East Queensland. Rhyolite/granite mountaintops and rainforests are common bedrock formations where these trees grow. Growing at elevations of 750-1,500 m above sea level. Wet/moist tropical rainforest conditions are where this species thrives. |
| Bark/Stem Description | The bark is smooth and has a blackish purple colour to it, hence the Latin name atropurpurea translating to ‘dark purple’. Larger trees have more of a brown tinge to the bark than purple. Its exfoliating appearance is an easy identification characteristic as well
as the colour. The trunk is very long, cylindrical and straight with diameters recorded up to 2 m. Due to its long life span and slow growth, the wood is strong, pest resistant and was logged for these qualities in the past. Settlers used this timber as a building material because of its high strength and durability. The use of this species as a building material reduced species numbers and caused the eventual fragmentation of the modern population. The stem is a purple/black colour and has irregular to horizontal branching. Resin leaks out of scars/wounds to the bark's surface. |
| Leaf Description | The Blue Kauri leaf complexity is lanceolate, measuring 35-45 mm long and 8-14 mm wide. These leaves are arranged in a distichous, opposite formation and have an acute apex tapering off into a point. The leaf margin is entire, smooth all the way around and has longitudinal venation. Has an acute base attached with a very short petiole. Leaves
are a vibrant green colour with a waxy layer. |
| Fruit Description | Male cones are cylindrical in shape and produce pollen; typically up to 30 mm long. Female cones are much larger and rounder, almost like a spool of thread (hence the Greek word ‘agathis’ translating to ‘ball of twine’). There are approximately 100 - 150 overlapping scales per cone. Indicative fruiting time is recorded to be December to January. Seeds are dispersed via winged structures (about 12 mm long, 15 mm wide) during the wet season. |
| Colour Description | The bark of younger/smaller trees displays an exfoliating purple/black colour and develops a more brown/purple colour with age. Similarly, the stems are also a dark purple-black colour. The leaves are a lush green with an almost waxy-looking coating. The female cones are a lime green colour. The resin that leaks out from wounds and scars in the bark is white. |
| Texture Description | The bark is smooth with texturized irregular exfoliation. Leaves have a waxy, almost glossy look to them. The resin is sticky and viscous. Texture remains stable throughout the growing season since the climate does not fluctuate. |