Tag Archives: landscape trees

A fossil, but very much alive – Ginkgo biloba

At the front of the Cambrian Lodge Motel in Cambridge on the main road to Hamilton, this ginkgo has been a remarkable sight for many years. Its wide spreading habit of growth belies the usual pyramidal form and may possibly be a result of having been topped and trimmed over several years earlier in its life.

At the front of the Cambrian Lodge Motel in Cambridge on the main road to Hamilton, this ginkgo has been a remarkable sight for many years. Its wide spreading habit of growth belies the usual pyramidal form and may possibly be a result of having been topped and trimmed over several years earlier in its life.

Ginkgos are remarkable trees – botanically, in the landscape and in traditional medicine. They are spectacular at this time of year with their pure golden colour and must be one of the showiest stars of autumn. I am assuming the common name of “maidenhair tree” has come about because of the resemblance of leaf shape to the common maidenhair ferns. The leaves are flat, neat little fans

I say they are remarkable botanically because they are a living fossil and in a family of one. In the kingdom of plants, tracing down from the highest order – the division of Ginkophyta – all the separate classifications descend to one solitary species, Ginkgo biloba. Mind you, it is dioecious which means that specimens are gender specific and both male and female are needed to get viable seed. It is called a living fossil, because it has been around for a length of time variously estimated between 160 and 270 million years. That is such a huge time span that it is a bit irrelevant whether the lower or upper figure is more accurate. Suffice to say, the dinosaurs may have browsed on ginkgo trees and they have outlived all their botanical relatives, surviving not only the dinosaurs but also climate changes and all diseases. That is pretty remarkable.

Ginkgo leaves have a distinctive fan shape. These are on a tree in the Gil Lumb Park in Leamington. The foliage has long been used in traditional Asian medicine, particularly for its alleged memory enhancing benefits.

Ginkgo leaves have a distinctive fan shape. These are on a tree in the Gil Lumb Park in Leamington. The foliage has long been used in traditional Asian medicine, particularly for its alleged memory enhancing benefits.

If I hadn’t looked up the tree bible, The Hillier Manual of Trees and Shrubs, I would not have realised they are classified with conifers even though they produce seed, not cones. They are at the primitive end of the evolution of conifers.

Ginkgos originated in China and have long been regarded as sacred trees. This is just as well because they are pretty much extinct in the wild so if they hadn’t been cultivated for thousands of years in Asia and hundreds of years in Europe and North America, they may have been lost to the modern world. They are long-lived and can last well past 1000 years, though not so much in this country where any tree is lucky to last past a few decades at most. In other parts of the world, the populace are not quite so chainsaw-mad and even venerate old trees. The only tree accorded that status in NZ is Tane Mahuta.

With so many ginkgos planted in the area, there are sufficient specimens of both male and female trees to get consistent crops of the nuts. While the outer casing emits a deeply unpleasant odour, the inner kernel is prized in traditional Chinese cuisine.

With so many ginkgos planted in the area, there are sufficient specimens of both male and female trees to get consistent crops of the nuts. While the outer casing emits a deeply unpleasant odour, the inner kernel is prized in traditional Chinese cuisine.

Despite the unmistakeable aroma of the fallen seed (variously described as ‘malodorous’ or smelling like vomit), once the soft casing has been removed, the seed inside is a traditional food in China and other parts of Asia. The smell is apparently in the fleshy casing, not the seed.

More interestingly, ginkgo leaves have long played a part in Chinese herbalism. The science on their effectiveness in slowing memory loss has yielded mixed results but research continues. At this stage, it is not looking as if ginkgo offers a magic bullet to reverse or even slow Alzheimers. Even now, most of our modern medications still orginate from plants. It is one reason why maintaining global bio-diversity is so important.

What started me on ginkgos was the sight of some leaves Mark had harvested and left on the back doorstep. I laughed because I knew instantly that he was curious about their memory enhancing reputation. But he forgot to bring them indoors and the wind blew them away.

Trees take a while to mature and take on their final form but the usual conical shape can be seen developing in this tree which is in Lindsay Park in Leamington

Trees take a while to mature and take on their final form but the usual conical shape can be seen developing in this tree which is in Lindsay Park in Leamington

First published in the Waikato Times and reprinted here with their permission.
All photographs courtesy of my friend Michael Jeans, Photographer, Cambridge.

Plant Collector: Metasequoia glyptostroboides

Metasequoia, commonly known as the dawn redwood

Metasequoia, commonly known as the dawn redwood

Most people know this by its common name, the Dawn Redwood, though this can cause a little confusion if you mentally associate the massive redwoods with North America. Those are the sequoia and sequoiadendron whereas the metasequoia is a Chinese plant (though botanically related). It wasn’t even identified and recorded until the 1940s, which is very late in the piece for botanical discoveries, certainly of something that large. For it is a very large tree – this specimen must be nigh on 30 metres now. We understand this specimen was planted in the mid 1950s here. Seed was sent from China to the Arnold Arboretum in the USA in 1948, just before China closed its borders for decades, and the arboretum then dispersed it around the world to ensure the survival of the species. So our tree must be one of the older ones in cultivation outside its native habitat, though is a mere baby for what is a very long-lived tree.

The other aspects that make this tree really interesting are that it is a conifer (bears cones) but it is deciduous. There are very few deciduous conifers. The leaves are turning colour now and will fall soon. In spring, the fine, feathery foliage (described as pinnate) emerges in bright green and garden visitors invariably ask us to identify the tree. It also has magnificent shaggy brown bark which is wonderfully tactile. It is just not a tree for suburban back yards but where space allows, it is a most handsome landscape specimen. It likes adequate moisture and we have it growing by a stream, but it is not as tolerant of wet roots as the other deciduous conifers, the taxodiums and glyptostrobus.

First published in the Waikato Times and reprinted here with their permission.

There are no shortcuts when it comes to notable trees in the landscape

A great grandfather's legacy - the canopy of rimu trees planted in 1880 as a shelter belt.

A great grandfather's legacy - the canopy of rimu trees planted in 1880 as a shelter belt.

New Zealand is a windy country. It seems self evident but it wasn’t until I started travelling overseas that I realised that the wind we have learned to live with here is not the experience of many. But you just have to look at a map and see our long thin islands surrounded by vast bodies of ocean and it is hardly a surprise that we have on shore winds, off shore winds, winds from the south, the north, the east and the west. It is the norm and consequently shelter belts in rural areas are also part of our landscape. Australians have commented to me about the predominance of clipped hedging in our garden landscape too and a lot of that has to do with minimising wind.

Many readers will be aware that hedges and plants are better at dissipating the blast of wind than a solid barrier. Walls and fences can funnel the wind up and over, protecting only the area in the immediate lea of the barrier because the air then flows down again. Even then, you are only protecting for the height of the wall so any time a plant gets its head above, it catches the full blast.

But it is not hedging for urban gardens that I have been thinking about, rather the benefits of a bit of creative thinking and plantsmanship when it comes to utility shelter belts. Here we benefit greatly from the vision of Mark’s great grandfather when he settled here 130 years ago. Presumably Tikorangi had already been cleared of most of its native tawa forest cover because the first thing Thomas Jury did was to get in and plant some shelter from the prevailing winds. Those trees give us our stately garden avenues today and we have learned much from looking at them. The more spectacular is the rimu avenue, often likened by visitors to the effect of a vaulted cathedral ceiling. Now those trees give us an environment which is one of the most special areas of our garden – and as it has taken well over a century to reach this stature, it is not easily replicated.

Our other avenue comprises mere pine trees, but pines of huge grandaddy stature – towering over 40 metres high and a mixed blessing. At ground level they give us wonderful gnarled old trunks, again in rows because of course they started life as a shelter belt. Above is a little more problematic with falling pine cones and a few swinging branches but nobody has been injured so far. Both avenues continue to perform their initial function – they break the wind and shelter the garden.

How many of today’s shelter belts will still be around in another century? And how many are planted in trees with the potential to add significant impact to the landscape? Leightons Green, phebalium, nasty yellow conifers or pittosporumns … I don’t think so.

After 130 years, our Pinus muricata are somewhat more compact than the P. radiata windbreak trees of the same vintage.

After 130 years, our Pinus muricata are somewhat more compact than the P. radiata windbreak trees of the same vintage.

It is of course Arbor Day tomorrow and that is a good time to make some shelter belt resolutions. These wind breaks do not have to be 100% cheap, utility and uniform. Dropping it to 90% cheap, utility and uniform is fine and there is the opportunity to use these shorter term plants of little or no aesthetic value to act as nurse trees for the long term landscape trees. For who will plant the rimu, totara, araucaria (Norfolk Island pines, monkey puzzle and the like, along with our own kauri), picea, abies, tawa, beech, oaks and other splendid trees with the potential for stature and longevity? As the size of town sections grows ever smaller, the need to continue planting potentially large trees in positions where they have the opportunity to reach maturity becomes correspondingly more important. Owners of lifestyle blocks have a chance to make a significant long term contribution and leave a worthwhile legacy if they just plant some decent trees. It is all very well thinking farmers should do it. Some do, but you can’t just plant trees in paddocks which are grazed. Trees have to be fenced off and that is very expensive and fiddly on a large scale. By their very nature, shelter belts are double fenced and planting is the easy part.

When it came to our own roadside shelter belts some fifteen years ago, Mark went for the mixed and layered approach. Quick, cheap cover came from expendable alders. Long term landscape trees are mostly kauri, rimu and totara, planted perhaps for our grandchildren and great grandchildren. Then, because we don’t have to buy the plants, seasonal impact has been added with magnolias – both showy deciduous types and larger growing evergreen michelias. The final layer is the roadside camellias – larger growing varieties surplus to garden requirements. They are a bit of a seasonal statement, some of our shelter belts, but also practical and planted with an eye to the long term future.

Many years ago, I wrote a column advocating that every person should plant at least one good, long term, landscape tree in a position where it has the chance to reach maturity. I recall two responses. The first was: “What, only one?” Fortunately a few will plant many but that only compensates for some of those people who will never, ever plant a decent tree in their entire lifetime. The second person castigated me for being too honest about how large a large tree will eventually grow. “We will never sell any if people know how big they can get,” she said.

In my books, landscape trees are large, handsome and long lived. These are not to be confused with pretty but low-grade, short term, quick impact trees favoured in most home gardens – the Albizia julibrissin, flowering cherries, robinias and their ilk. As a general rule, fruit trees will never make a landscape tree either. By definition, any plant with the telltale words compact or dwarf in the description will lack stature.

Our country is still somewhat raw and utility in our approach to trees. To many farmers, they are a waste of valuable grazing space and they get in the way of machinery in this heady world of high production but green desert farming. To many town dwellers, they block views and are messy. In a country with a tendency to cold houses, the shadow they cast is another black mark. Any tree of stature is measured in terms of timber potential, not landscape value. Compare that to the pride taken in the UK with their champion trees – those specimens judged to be the largest of their type in the country and awarded accordingly and in Europe where trees of ancient pedigree are venerated. I have seen the plane tree, now some 2500 years and definitely ailing, beneath which Hippocrates apparently sat to write the Hippocratic Oath. We have a long way to go yet here. Arbor Day would be a good place to start.

Rimu trees from 1880 in the background, mixed plantings from 1950 to now in the middle ground

Rimu trees from 1880 in the background, mixed plantings from 1950 to now in the middle ground