Gondwanan Plants What Are They and Why Grow Them in Britain?

Fig. 1.  An approximation of Gondwana before the commencement of break-up, showing the distribution of present day continents within the super-continent.  See White, 1994 for more maps.

Gondwana, a Potted History
If you ask anyone 'what is or was Gondwana?' The chances are that you would receive a blank look.  Hopefully after reading this you might have a vague inkling .about the word.

The theory of Plate Tectonics, that the continents are a relatively thin and fractured skin floating over the mantle and that they move slowly around through disturbances from below, is now fairly universally accepted.  It is thanks largely to research in modern countries that once formed part of Gondwana that we can be so certain of this.

At one stage in Earth's history (From the Late Silurian period c. 415 Million Years Before Present) all the continents were massed into one super continent now referred to as Pangaea.  By 340mybp Pangaea began to split in two, Laurasia (containing what will become Eurasia and North America) from the northern half and Gondwana from the southern half.  As the sea filled the gap between the two Super Continents the land plants, and many land animals were isolated.  Evolution would continue largely separately on the two land masses, the effects of which are still clearly visible today, the considerable differences between the conifers of the two hemispheres for example.

Probably during the Early Cretaceous period (125mybp) the first ancestors of Angiosperms (flowering plants) began appearing, most likely in what was to become West Africa and North Eastern South America (the Atlantic would not open for several million years yet).  They quickly spread over Gondwana and diversified rapidly and spread up into North Africa and Europe.

The Cretaceous also saw the break up of Gondwana, the Atlantic opened up, Africa and South America broke off from the still temperate and unfrozen Antarctica.  90mybp the Indian sub-continent begins an epic journey north, finally colliding with Asia 50mybp, and it is still going north at around 6cm a year pushing the Himalayas up ever higher.  Between 80 and 60mybp the New Zealand Sub-Continent began to part from Australia with the spreading and sinking of the Tasman Sea taking many of their common plants with them.  The term 'New Zealand Sub-Continent is used as much of what is present day New Zealand was formed by later vulcanism & tectonic action.  The then, much larger, landmass still stretched from below all the main islands of modern New Zealand to New Caledonia along the Lord Howe and Norfolk Rises and also out along the Chathams Rise.  These are named for the Lord Howe, Norfolk and Chatham Islands respectively, all of which small relict points of land show their continental origins by their very high levels of biodiversity and endemism (species found there & nowhere else) today.

From 60mybp onward New Zealand was isolated from Australia and it's unique flora began to further develop and diversify, but the earlier links are still evident.  The Manuka or tea bush (Leptospurnum scoparium) is found in both countries in only slightly differing forms, the Hop Bush (Dodonaea viscosa) are found on both sides of the Tasman Sea.  There are several examples of plants that have diversified more in on country than the other such as Pittosporum and Celmisia which have more on the New Zealand side and Epacharis on the Australian side.  Some arose on the western side of the Tasman Sea & their light windborne seeds were blown to New Zealand where they grew & in time diversified into many of the unique species found there today.  It would seem that all members of the Daisy family arrived in this manner as the first fossil record of Asteraceae is from the Oligocene (just 34-24mybp), long after New Zealand become isolated.

After the Tasman Sea opened only Australia and Antarctica remained attached until 45-50mybp when the South Tasman Rise was breached and the uninterrupted circum-polar Antarctic Ocean was formed.  Australia is still drifting northwards today and in around 20 million years the top of Australia should reach the Equator.  The separating of Australia & Antarctica had dramatic global consequences.  With the opening of the Antarctic Ocean a circum-polar current developed, so diverting the warm waters from equatorial regions which could previously flow all the way to the Antarctic shore.  Without this warm water & associated air input polar Icecaps began to form and slowly higher plant and much animal life was excluded from the giant continent.  The periodic warm periods that our planet experiences occasionally allowed some re-colonisation via Tuerra Del Fuego to the Antarctic Peninsular.  The loss of the warm equatorial waters to the Antarctic gives an ominous warning to us in Britain.  In Scotland we lie on the same latitude as Labrador in Canada which is locked by sea ice in winter as it lacks the warming effect of the Gulf Stream coming up form the Gulf of Mexico with which we are blessed.

So where are the 'Gondwanan Plants' today?

The floating arks of the fragmented Gondwana took many of their plants and animals with them as they slowly made their way to their current locations.  As they travelled their climates and conditions changed, the inhabitants were forced to adapt to the conditions, those that are here today could, those that couldn't are found only as fossils in the rocks and sediments.  Those fragments (Africa, India & South America) which collided with Laurasia  met with sudden influx of new species from the north and of course many Gondwanan species moved north and continued evolving there.  The cactus family Cactaceae, for example has spread to above the Canadian border from its South American origins. In the other direction a familiar example from the animal kingdom, the Jaguar, a northern feline invader and it's relatives soon displaced the indigenous large marsupial predators.

Present day strongholds of Gondwanan origin flora include Andean and Southern South America, the incredible flora of the Cape floral kingdom and much of the rest of Southern Africa.  The now sadly much depleted flora and fauna of Madagascar, famous for its Lemurs a classic example of a Gondwanan mammals.  The Indian subcontinent split perhaps too early to take much of the flowering Gondwanan flora with it and its traumatic journey north and its subsequent collision and associated influx of Laurasian plants with Asia eradicated much of what remained. There are still representatives, such as Parochetus comminus the ever-popular 'Blue Clover' found today throughout the Himalayas and high up in the mountains of East Africa.  The Australasian plate (which includes New Guinea) drifted close enough to the Islands of Indonesia to allow stepping stones through New Guinea over the land of what is now the still shallow Arafura sea into Northern Australia.  Plants such as Rhododendron northiae of the tropical rainforests of Northern Australia are obvious later arrivals. Aboriginal Australian man probably also come via this route.  The large unbroken and flat nature of Australia resulted in extensive deserts forming after separation from Gondwana. For these new habitats new plants evolved from the original Gondwanan stock, giving rise to many of the now familiar plants of the Australian arid 'Bush'; Eucalyptus, Wattles, Banksia and Grass Trees amongst them.  The mountainous Southeast of Australia and Tasmania remain the 'most Gondwanan', here the wet and cool climate is much as that of the temperate forests of Gondwana, it is in these areas that most of the plants that are to be found elsewhere in the Southern Hemisphere are to be seen. 

It is not just plants which were carried in these Southern Ark continents as they drifted, animals from opposite ends of the world are still closely related and others show very similar evolutionary paths. The many Marsupials for example in Australia and South America remain as testament to Gondwana.

The plants still show many similarities, to give the most attractive example is perhaps in the family Proteaceae. The wonderful Waratah, Banksia and Grevilleas of Australia, the Proteas of South Africa and the much desired 'Chilean Flame Bush' (Embothrium coccineum).  Elsewhere in the former Gondwana where the climate has remained suitable to their survival members of Proteaceae have persisted.  The incredibly diverse and unique flora of New Caledonia has many representatives, but where the climate was colder there are fewer if any.  Tasmania has but a few compared to the mainland, 2 Banksia (c. 50 species on the mainland of Australia), one Grevillea (c. 340) and one Waratah (4) are among the most note worthy.  New Zealand has but two representatives, the Toru (Persoonia toru, of a genus many members in warmer, drier Australia including 2 in Tasmania) and the New Zealand Honeysuckle (Knightia excelsa). It is worth noting that both of these are found in warmer areas, mainly of North Island.  Where the climate is very wet and cold Proteaceae are generally either poorly represented.  This family of hundreds of diverse garden worthy plants tells us not just of the present southern continents origins but also of the adaptive potential of plant groups.

Hopefully the reader is now clearer on what Gondwana was i.e. the Southern Super Continent whose constituent still form much of toady's land mass in the Southern Hemisphere.  Also what constitutes a 'Gondwanan Plant', i.e. a plant for which its evolutionary origins can be traced back to the flora of Gondwana.

The most frequently cited example of 'Gondwanan Plants' are the Nothofagus or Southern Beech.  A genus of around 40 extant species of trees found in Australia (3 Species), Chile & Argentina (9 species), New Caledonia (c.5), New Guinea (c.14) and New Zealand (4).  Fossil evidence has shown that they were long the dominant trees over much of Antarctica but none have been found in Africa, thus we can surmise that Africa had split from Gondwana before Nothofagus arose or that conditions there were never suitable to their establishment.  The correlation of the distribution is more easily seen from bottom-up perspective, rather than the equatorial projections we are more used to.  With a map centred on Antarctica one can imagine a strip running from Chile to New Zealand running through Antarctica (See Poole, 1987, Wardle, 1984 & White, 1994).

Why should we grow Gondwanan Plants?

Amongst these plants are to be found some of the most beautiful in the whole plant kingdom, with species exhibiting every colour and form imaginable.  More usefully Gondwanan plants are to be found in a great diversity of habitat and in many cases have become very well adapted to them.  Where we are on the Northwest coast of Scotland there are several great obstacles to gardening, the near continuous violent salt-laden westerly winds, the high rainfall and lack of soil.  These conditions are not ideal for growing the majority of the more common 'garden plants', which object to one or more of these constraints.  Amongst the plants of Gondwana origins one may find many 'garden worthy' subjects perfectly adapted to just these conditions.

For the exposed West coast of Scotland a good example is that of seaside hedging for wind breaks.  Plants of Northern hemisphere origin suitable to growing as a windbreak while still being aesthetically pleasing are few; Rosa rugosa, Elaeagnus x ebbingei, Contoneaster spp. & Hydrangea spp. In parts with more shelter, brooms and Ceanothus in drier areas.  This list is far from complete but one must agree it is fairly representative and even some of these are somewhat lacking in the aesthetic.

Many of the plants of the Southern Hemisphere are particularly well adapted to places exposed to strong salt-laden winds.  Looking at a globe it is easily seen that the Temperate Southern Hemisphere has far less landmass than the Temperate Northern Hemisphere.  As mentioned earlier after the break-up of Gondwana a circum-polar ocean developed, stretching right around the globe and interrupted only by occasional small islands to slow the winds or break up the waves.  The Southern seas have become notorious for their mountainous seas and storms. The 'Roaring Forties' and 'Furious Fifties' have claimed many ships.   It is on these Islands and the brave bits of land that stick themselves into the path of the winds that many of the best plants for our exposed coastal areas are to be found.

From these Gondwanan shrubs we are spoilt for choice, amongst the most commonly used are the indestructible Olearia macrodonta, O. cheesmanii, O. solandri, O. traversii and tens of other species of Olearia of New Zealand.  Escallonia spp., most frequently E. rubra

& hardy Fuchsias of many varieties from the bottom of South America,  Hebe spp., larger species such as H. eliptica, & H. salicifolia which grow wild in both New Zealand & Chile, as well as other sorts like H. speciosa, H. x  franciscana and H. parviflora make excellent flowering hedges that are barely bothered by the wind.  For a more plain hedge there is the apple green of Griselinia littoralis.  Bereberis darwinii is excellent as a spiky hedge in a windy spot with it's thousands of rich golden flowers.  Leptospernum scoparium, the manuka is available in countless forms and colours.  Many Eucalyptus may be coppiced into hedges of vibrantly coloured foliage, Callistemon the Bottle brushes of Australia for a lax hedge, what better site than a hedge of Embothrium, the flame red flowers illuminating the garden in June.  The Southern Rata, Metrosideros umbelata, with it's masses of red pom-pom flowers has the honour of being the dominant shrub on the Auckland and Campbell Islands below New Zealand at more than 50º South or the beautiful  Pohutukawa, Metrosideros excelsa, for the milder windy garden.  It is probably wise to stop this list here before I loose what few readers have made it this far!

The main failing of the hardy Gondwanan plants is that many are not cold hardy enough to survive everywhere in Britain, those living Grampian, upland Yorkshire or Northumberland may find that many of the plants I have listed above, while excellent at coping with wind are vulnerable to their harsher frosts.  But the Southern Hemisphere is not a universally mild and temperate place, as with the Northern Hemisphere, there are cold regions and mountain ranges to be found.  Indeed some of the highest mountains outside the Himalayas are to be found in the Andes.  The Southern Alps of New Zealand, the Highlands of Tasmania, the Snowy Mountains and The Grampians of South East Australia and the Drakensburg of South Africa all have many excellent plants to offer those who live in Braemar.

References and some other useful publications:
W Arnold-Forster 'Shrubs For The Milder Counties' Published by Alison Hodge, Penzance, 2000.  The new second edition of this work originally written in 1948 contains an addendum of plant-name changes by Peter Clough, former head gardener at Inverewe, near to us. Full of the authors experience of gardening on an exposed Cornish moor with descriptions of hundreds of exotic shrubs from all over the world, many of which, new to us then, have become garden favourites 50 years later.
W. J. Bean 'Trees & Shrubs Hardy in the British Isles' 8^th ed., Vols. 1-4, Published by John Murray, London, 1980, Supplement 1988.  90 years after it was first printed this is still the standard work on the subject.
M. I. H. Brooker & D. A. Kleinig 'A Field Guide to Eucalypts' Vol 1 . Bloomings Books, Victoria, 1999.  Covers Southeastern Australia and Tasmania, and so all of the hardiest species.
Yvonne Cave & Valda Paddison 'The Gardener's Encyclopaedia of New Zealand Native Plants' Published by Random House, Auckland, 1999.  Obviously predominately written for native gardeners there, but crammed with good pictures & up-to-date descriptions of most of the varieties you are likely to encounter in gardens & nurseries here.
W. M. Curtis , 'The Students Flora of Tasmania', Published by D. E. Wilkinson, Tasmania, 1967-94
'Flora of New Zealand' Volumes 1, 2 & 5 Published by A.R. Shearer of Wellington.
'Flora of Southern Africa' is a massive work in many parts which is available from the National Botanical Institute in Southern Africa (see Links Page).
V. Heywood Ed. 'Flowering Plants of the World' Batsford, London, 1978. Though the classification of some of the families has change since its publication it remains a thorough & accessible work giving information on all major Angiosperm families.
Graham Hutchins' 'Hebes Here & There' and available from County Park Nursery, Hornchurch, Essex
Jamie Kirkptrick, 'Alpine Tasmania' Oxford University Press, Melbourne, 1997. An excellent clearly illustrated field guide with some lovely photos by Peter Domrovskis in the middle.
Any of Lawrie Metcalfe's series of books published by Random House 'The Cultivation of New Zealand ……'
P. Olde & N. Marriott 'The Grevillea Book' Vols. 1-3, Published by Kangaroo Press, New South Wales, 1995
David M. Moore, 'Flora of Tierra del Fuego' Anthony Nelson, Shropshire, 1983
Roger Phillips & Martyn Rix's 'Garden Plant Series' published by Macmillan are invaluable as sources of many fine images and often useful information on the plants in their natural habitat.  Most applicable to Gondwanan plants are 'Shrubs', 'Perennials' Vols 1 (Early) & 2 (Late), 'Annuals and Biennials' and 'Conservatory & Indoor Plants' Vols 1&2 which contains many plants hardy outside in the milder Counties, we have also found that most of the estimates of hardiness are rather conservative in these volumes.
A. L. Poole, 'Southern Beeches', Published by Science Information Publishing Centre of Wellington in 1987.
James B. Reid et al 'Vegetation of Tasmania' Published by Australian Biological Resources Study, Hobart, 1999.  Great book if you are really interested in Tasmanian plants, very up-to-date and full of interesting info on not just the ecology of the Island itself.  Not cheap, or for the uninitiated, has a massive bibliography.
John T. Slamon, 'A Field Guide to the Alpine Plants of New Zealand' Godwit, Auckland, 1999. Most of the commonly encountered upland plants of New Zealand are described with photographs.
'Tylor's Guide to Seashore Gardening', ed. F. Tenenbaum, Published by Houghton Merlin Company, New York, 1996
John Wardle, 'The New Zealand Beeches - Ecology Utilisation & Management', Published by New Zealand Forest Service, Christchurch in 1984.
M. E. White, 'Greening of Gondwana' 2^nd edition, Published by Reed of New South Wales in 1994.
Hugh D. Wilson, 'Field Guide: Stewart Island Plants' Manuka Press, Christchurch, 1994.  Exceedingly useful book if you ever visit the southern most of New Zealand's three main islands.  All 580 vascular plants native to the island are described and illustrated with much other useful information besides.
For more books see our Recommended Reading List.

Phew, hope you managed to take in some of that!  Basically lots of plants from the colder bit of the Southern Hemisphere grow well here so we offer them for sale, in the hope you will buy them, be impressed with them & come back for more.

©Ben Rushbrooke,  April 2004

Windbreaks
Coastal Gardening
What is Gondwana, a shorter answer
Rabbits in your garden

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