I thought it was time to write something more Australian than I've done recently, and it being gloriously spring here at last (and unsurprisingly, with each year spring becomes more precious) flowers seemed an appropriate topic. For no especial reason I thought of the lovely and diverse Grevilleas as a topic, but when I started planning the post I realised that we needed a bit more context, so felt obliged to start with the wider family, the wonderful Proteaceae. (There's probably a name for a brain that obliges me to be so structured, but it doesn't matter because that's the only one I've got, or am likely to have.)
The family is essentially Gondwanan and old one, centred on Australia but represented strongly in southern Africa and to a lesser extent in South America, India, New Caledonia and New Zealand. It has spread north into Africa, into Indonesia and south-east Asia, and into central America and Mexico. There are some 1700 species in about 80 genera; of these 1100 species and 46 genera are Australian.
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| Woolly Grevillea G. lanigera Namadgi NP near Canberra. This is the largest genus with some 360 species, virtually all Australian. The typical Proteaceae flower - though no single statement is likely to be universally true in such a diverse family - has four tepals (the term used for petals and sepals which can't be reliably defined as one or the other) with a style which first bears pollen and later receives it. |
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| Notro or Firebush Embothrium concinnum, Torres del Paine NP, southern Chile. A small but spectacular South American genus whose close relationship with the Australian waratahs (Telopea) is evident. |
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| Protea nitida near Cape Town - a scan of a somewhat faded old slide. There are nearly as many Protea species as there are of Grevilleas. This is the genus from which the family takes its name - in other words it was the first genus in the family to be named. The great Linnaeus named it for the Greek god of that name, noted for having many shapes. That description is appropriate for the entire family too, but despite some assertions that was not why the family was named! |
The Gondwanan distribution has generally been taken at face value - ie evidence of an ancient group which was present when the southern continents went their own way. Recent molecular dating work (eg DNA sequence research), especially involving Dr Peter Weston of the New South Wales Herbarium, suggests that, counter-intuitively, the various groups dispersed outward from Australia at different times to colonise the rest of their current range by oceanic drift. (A similar result was recently suggested too by research into the ratites - the giant flightless southern birds - suggesting that they must all have flown to their current sites across the southern hemisphere and then all independently lost the power of flight.) All things are of course possible, and I claim no expertise, but both these scenarios seem remarkable to say the least, when compared with the more obvious traditional explanations. I wonder if there is more to be said on this.
Proteaceous plants can be trees, big shrubs, sprawling ground covers and even, in some cases, herbs. In addition to the characteristics noted above under the Grevillea photo, in many species the anthers are attached to the inside of the floral tube. The tip of the style, the stigma, is touching the pollen; as the style grows it puts pressure on the sides of the flower tube until it splits; at this stage the stigma springs out, still bearing the pollen which is taken by either insects or birds depending on the species. Shortly afterwards the stigma grows a brush and becomes a conventional pollen receptor. Flowers may be single, paired or in large spikes.
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| Grevillea pectinata near Salmon Gums, southern Western Australia. The upper styles have emerged, the lower ones are still trapped in the flower tube. |
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| Banksia speciosa cone near Esperance, southern Western Australia. Only a few of the numerous flowers are usually fertilised. |
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| Recently burnt fruit of Mountain Devil Lambertia formosa, near Nowra, New South Wales. The devil's head will soon split to drop the seed into the ash bed. |
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| Hakea microcarpa fruit, Tidbinbilla Nature Reserve near Canberra. Most Hakeas have thick woody cones, but this one has smaller more fragile ones; Grevillea and Lomatia have even more papery fruits. |
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| Persoonia sylvatica fruit, Tinderry Nature Reserve south-east of Canberra. |
Another family characteristic (though again not univeral) is the presence of curious root structures called proteoid roots, which grow annually as short very dense masses of root hairs from the sides of normal roots. Their function is similar to that of mycorrhiza (fungal 'hairs' associated with a plant's roots) in other plants, providing a greatly increased root surface area to contact scarce soil nutrients and water. Proteaceae don't have mychorrhiza; the proteoid roots seem to have an association with soil bacteria.
Species are found from very arid central deserts to wet near-coastal forests.
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| Hakea lorea, Kata Tjuta NP, central Australia |
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| Monga Waratah Telopea mongaensis, Monga NP, south-eastern New South Wales. |
Most plant families have either vertebrate or invertebrate pollinators, but it is probably unsurprising that such a large family should have many strategies; mammals, birds and insects all have roles in different branches of Proteaceae.
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| Western Little Wattlebird Anthochaera chrysoptera on Banksia speciosa, Esperance, Western Australia |
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| Native bee on Persoonia sp. (Probably Xylocopa sp. - thanks Susan.) |
Five subfamilies are recognised, all being present in Australia.
Symphionematoideae comprises just three species in two genera; Symphionema in New South Wales and Agastyachys in Tasmania
Bellendenoideae has just one species, from the highlands of Tasmania.
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| Mountain Rocket Bellendena montana, Ben Lomond NP, Tasmania. The flowers form white spikes in summer; these are the seed capsules. |
Persoonoideae comprises five genera; four are very small and recent work suggests that three of them should properly be included in the best-known genus of the group, Persoonia.
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| Persoonia linifolia; the tepals have rolled back to expose the four anthers and central style. |
Proteoideae is a bigger grouping, containing 25 genera including nearly all the African ones.
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| Stirlingia latifolia, Badgingarra NR, north of Perth. Commonly known as Blue Boy because cement made from the sand it grows in turns blue! Stirlingia has just seven species, all from Western Australia. |
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| Conospermum distichum, Cape le Grande NP, south-west Western Australia. Members of the genus are known as smoke-bushes, as they grow en masse on heathy sandplains, causing the landscape to appear hazy. Fifty species are found across southern Australia. |
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| Isopogon divergens Kalbarri NP, Western Australia. (My thanks to Phil Trickett and Catriona Bate for identifying this beauty for me.) Often known as drumsticks for their globular seed cases, the 35 species are found across Australia, though most are in the west. |
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| Petrophile pedunculata cones, Nowra, New South Wales. These are generally called conesticks from their more elongate woody fruits. There are some 70 species, again mostly in the west. |
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| Adenanthos terminalis Heggarton Conservation Park, Eyre Peninsula, South Australia. The jugflowers or woolly-bushes are most atypical in the family, not least in having just one flower in the inflorescence. This species from the South Australian mallee, and one from Victoria, are the only two of the thirty species not restricted to Western Australia. |
Grevilleoideae contains the 'big three' Australian genera, plus most of the Australian rainforest species, the Malesian species, and the American ones.
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| Grevillea juncifolia, central Australia. A spectacular desert-dwelling member of the biggest genus (370 species, nearly all being Australian). And it will get its own posting in the not too distant future... |
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| Massed Banksia menziesii (red) and M. hookeri, Lake Logue NR, north of Perth. Banksia inflorescences can have thousands of individual flowers and are immensely attractive to mammals, birds and insects. They too warrant their own posting, not least because there are 170 species, but... |
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| Dryandra formosa near Albany, Western Australia. In 2007 this large genus was absorbed into Bankia based on evidence that appeared to me comprehensive at the time but has by no means been accepted by authorities much more qualified than I, including the Dryandra Study Group of the Australian Native Plants Society, and eminent West Australian botanist Alex George. Since publishing this post I have been sent Alex's article challenging the change, and I find his arguments compelling. For those who do accept this radical change, it more than doubles the number of Banksia species, including this species which would be known as Banksia formosa. |
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| Hakea multilineata near Norseman, inland southern Western Australia. There are 150 Hakea, found throughout Australia, though again concentrated in the west. The similarities with Grevillea may not be coincidental - there are rumblings that suggest there may soon be over 500 Grevilleas and no Hakeas! |
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| Lomatia polymorpha, Mount Field NP, Tasmania. This genus of 12 species is found on the Pacific sides of both Australia and South America. |
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| Lomatia hirsuta, Volcano Orsono near Puerto Montt, southern Chile. |
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| Lambertia formosa Nowra, New South Wales. These flowers produce the Mountain Devil fruit pictured above. This is the only eastern species, but well known; there are another nine in the west, where they are widely known as honeysuckles. |
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| Woody Pear Xylomelum angustifolium fruit, Lake Logue NR, north of Perth. A striking small tree, and an unusual genus in this context in that there are more species in the east (four) than in the west (two). |
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| Orites lancifolia, high Namadgi National Park, above Canberra. In addition to the seven Australian species (most of which are Tasmanian) there are two in South America. |
Well, if you're still reading after all this - thank you! I hope it's been worth it. As noted, there will be postings on two or three of these genera in the future but for now that's enough! If you can go and see some actually growing now, so much the better.
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