Once more into the Wiggy Wig Bush!

New Zealand is an island (well, two islands) and has been for millions of years. Geographic isolation has resulted in many an evolutionary quirk occurring within both the island’s flora and fauna and as it stands today 80% of the country’s trees, ferns and flowering plants are classified as ‘endemic’, meaning that they naturally occur no where else on Earth. One such quirk is the rather splendid and unusual growth habit known as Divarication. Divaricate plants have small leaves and wide angled branches that grow in a characteristic, interlacing ziggidy-zaggedy manner producing a dense, highly tensile shrubby mass. While plants exhibiting this form are found throughout the world, they are nowhere as prominent as within NZ’s flora.  Around 10% of the country’s woody plants display this growth habit with specimens occurring across 18 different taxonomic plant families. Bizarrely, certain plants, such as the Kōwhai tree (Sophora microphylla) have a divaricate form as the juvenile stage of their development before adopting a more conventional branching arrangement as they mature. A prime example of a plant with a strongly divaricated habit is our old friend the Wiggy Wig Bush (Muehlenbeckia astonii) with its highly geometric, molecular shaped branching.

The Wiggy Wig Bush- A fine example of Divarication

Close up zig zag

A number of theories have arisen to explain the penchant for divarication of New Zealand’s plant life.  Some have postulated that the dense and tangled branch growth had evolved as a defensive response to the browsing of the now extinct Moa, a large flightless bird similar to the modern day emu. Indeed, such a theory would explain the juvenile divaricate habit of certain plants as once of a mature height they would no longer be at risk from browsing animals. Others claim that divarication aids plants in protection from dry and windy climatic conditions by acting as a windbreak, reducing transpiration from the plant’s inner leaves and limiting water loss.  The inner depths of a divaricate shrub also provide a hospitable environment for native lizards such as skinks and geckos. In return for acting as agents of fruit and seed dispersal, the lizards are provided shelter and protection by the interwoven branches of the plant.

The Moa in action

A range of plants exhibiting a divaricated growth habit can be viewed in the Native plants section of the Dunedin Botanic Gardens.

Off the Road

Well, avid readers, I'm back! Following an extended summer jaunt that saw me successfully take in a good portion of New Zealand's South Island (and only exploding my van’s battery once) I have landed back in Dunedin once again to carry out the final two months of my placement. Though, admittedly, most of my time on the road was spent recreationally, I did set aside some time to look into a blog-worthy project that has been of interest to me since my arrival on these far flung shores. Two weeks into my time here in Dunedin, I heard about a family that had established and grown what was being described as a ‘Forest Garden’ at their home in the small coastal town of Riverton. A low energy input growing system based upon the ecological relationships of a forest, an established 'forest garden' is able to produce an abundant variety of perennial vegetable and fruit crops with a minimal amount of maintenance. The concept fascinated me with its unique combination of ecology, inventive design, biodiversity and practicality. After doing some more research, I managed to get in touch with Robert and Robyn Guyton and arranged a week’s stay with them in order to view their work first hand and help out in any way that I could. 

The Guyton Household- Riverton, NZ

As it turns out, very little help was required in the forest itself aside from a few small plantings- a testament to the low maintenance requirements of the garden! However, the Guyton’s food forest is just the tip of the iceberg in terms of their environmental endeavours and there was plenty to get my teeth stuck into! Since moving to Riverton over twenty years ago, Robert and Robyn have been instrumental in establishing a number of fantastic horticultural projects including a community orchard (and a secret guerilla orchard), an organic gardeners network, a living catalogue of heritage varieties of fruit tree specific to Southland, New Zealand and Riverton’s very own Environment Centre, a one stop shop for organic produce and information located on the town’s main street. Inspiring doesn’t even begin to cover my time in the company of these lovely and incredibly generous folks. Upon my arrival, Robert gave me a detailed tour of “the system” as he referred to it, which covers almost two acres surrounding the family home.

View from the back door.

Meandering through the garden, it did not take long to become totally immersed (and a bit disoriented) within its wild beauty. The ground is thick with leaf and plant matter that is left where it is to decompose rather than being swept aside and turned into waste. Robert informs me that this process of heavy mulching with organic matter over the past 20 years has led to test sample of soil displaying a perfect balance of all nutrients apart from selenium (and that is only because the element is lacking in all of New Zealand’s soil). Beneficial perennial herbs form a healthy understory for apple, plum, peach, walnut and hazel trees dotted across the landscape. Each fruit tree has been selected and grafted by Robyn who delights in telling me their history as we pick and grade apples later in the week.  Scattered throughout the system also are currant and raspberry bushes that give off a bumper crop of soft fruit each year. All in all around 450 plant species are grown within the garden, many of them edible- all of them useful. There is no weeding to be done in the system either as carefully planned succession of plantings and lack of open cultivated ground keeps common weeds from taking hold. Pests and diseases are similarly notable by their absence. Thanks to the innate biodiversity of the forest garden, pests are predated on before they get to become a problem. Unlike many conventional gardens, plant are protected through solely natural means without needing to resort to toxic chemicals time and time again as a short term solution.

Deep in the Forest...

I believe that a lot can be learned from the Guyton's forest garden. It serves as a useful reminder that horticulture need not be a constant battle against plants and their natural processes but a joyful and beneficial undertaking, for both gardener and the environment alike! It is amazing what you can do when you don't have a lawn...

Not a blade of grass in sight!

I would like to take this opportunity to thank the Guyton family for hosting me and allowing me into their home. Your time was gratefully received. Long may your forest grow!

The Guytons and I.

                                                                               

On the Road

As those of you following this blog may have noticed, there has been a lack of activity of late. Fear not! I have been on the road living out of the back of my van for the past month or so and have had very sporadic internet access. I will be back in action as of the 24th of February and will have info. aplenty for you all. Cheers in the mean time!

¡Ongaonga!

Urtica ferox- The Tree Nettle

Urtica ferox in Dunedin Botanic Garden

Though generally a safe and hospitable land in terms of predators and poisonous beasties, New Zealand is not entirely devoid of floral hazards that can pack a punch. Case in point- Urtica ferox, the native Tree Nettle or Onganonga. In the same genus as the UK’s own stinging nettle (Urtica dioica), Ongaonga is New Zealand’s very own supercharged endemic equivalent. It is easily distinguished from other members of its genus as its growth habit is that of a woody shrub rather than a herb.  The plant is widely distributed across both the North and South Islands of New Zealand and can mainly be found growing in areas of temperate bushland. Thickets of Ongaonga are not unknown and usually occur in areas of sloped debris. An incredibly hardy plant, Ongaonga is able to withstand temperatures as low as -8⁰C.

Tree Nettle is dioecious, meaning that male and female flowers occur on separate specimens of the plant. Small green flowers borne on spikes up to 8cm in length grow from the leaf axis of the plant between the months of November and March. Pollen from the male flowers is then dispersed by the wind to their female counterparts, which following successful pollination, develop into small, brown nut like fruits of one and half millimetres in length.

Leaves of the mighty Ongaonga

Perhaps the defining feature of the Ongaonga in terms of human interaction with the plant is its incredibly powerful and irritable sting. Stiff, hypodermic needle-like  hairs adorn the plant’s flowers and branches as well as the veins, stalks and edges of the deeply jagged leaves. Each hair is around 6mm in length. When touched the hairs break and release a potent mixture of intoxicants that can result in a host of painful and in very rare cases, deadly reactions. Though rare, there have been accounts of dogs, horses and even one very unfortunate walker meeting their maker at the hands of the Ongaonga’s sting. Fortunately for the rest of us, a brush with the Ongaonga will generally not result in death but rather a great deal of incredible discomfort lasting somewhere in the region of three days. Indeed, the variety and intensity of the symptoms brought on by the Ongaonga’s sting are quite remarkable (see table below).

Yowza!

Possible symptoms following contact with Tree Nettle

Time after contact	Symptoms
Immediately	Painful, burning sensation Numbness
15-20 minutes	Abdominal cramps Strong burning sensation in feet Visual blurring
60–90 minutes	Weakness, exhaustion Confusion  Pale skin Sweating Salivating  Cramps Breathing problems Loss of eye sight (!) Problems regulating body temperature Problems controlling movement of arms and legs

However, the Ongaonga’s lack of hospitality for the human race does not extend to all creatures. The Tree Nettle plays a vital ecological role in the life cycle of the Red Admiral Butterfly (Vanessa gonerilla), another species endemic to New Zealand. The butterfly lays its eggs amongst the spines of the Ongaonga’s leaves, which are the main food source of the Red Admiral Caterpillar. The caterpillar also uses the plant as protection from predators by folding the leaves around their bodies effectively creating a makeshift tent. Fantastic!

 

Red Admiral Caterpillar in a tent

Though eradicating the Tree Nettle would undoubtedly remove a potentially harmful element from our environment, the ecological implications for other inhabitants of our planet would be massive. Ongaonga is not just a plant, it is a home and nourishment for other species. Remember this if you are ever stung and your arms and legs start flailing wildy, your vision blurs and your body temperature begins to fluctuate. It may seem like a good idea to go back and exact horticultural vengeance but be mindful folks and look at the bigger picture.

Rock, Water and Alpine

Rock Garden

For the past month I have been maintaining the gardens' Rock, Water and Alpine collections under the guidance of the collections curator, Robyn Abernethy. A diverse collection, the Rock, Water and Alpine section has been in development for over a century and boasts a vast array of beautiful and fascinating plants from around the world.

Dunedin Botanic Gardens’ Rock Garden is located in the lower section of D.B.G and is constructed on a northwest-facing hillside next to Lindsay Creek, a small waterway that flows through the lower gardens. The hospitable topography of the site allows for plants to receive maximum sunlight (bare in mind that this is the southern hemisphere folks- north is the new south!) whilst simultaneously being cooled by the amiable breezes that that blow down along Lindsay Creek. Construction of the rock garden began in January 1904 and was overseen by newly appointed Superintendent David Tannock. In 1911, the garden had grown to be 150m long and was populated by a collection of 150 native plant species.

Over the following century the rock garden has undergone numerous developments. After a period of degradation during the second world war due to lack of labour and supplies, a major renovation of the site was instigated between 1950 and 1960, which saw a reduction of the steepness of the slope on which the garden sat and the addition of terraces on the Lindsay Creek side. An assortment of new and larger rocks were also excavated from nearby ‘Three Mile Hill’ and incorporated into the design. The rock garden remained unchanged until 1989 when a large overgrown area at the north end of the site was developed, boosting it in size to over 2000m².

Today, the Rock Garden is one of the main features of the lower section of D.B.G, displaying around 940 plant species and cultivars ranging from bulbs and herbaceous perennials through to shrubs and trees. With only a staff of two to maintain the area, weeding it can be a daunting task. However, to the casual observer and the keen eyed horticulturalist alike the Rock Garden in Spring is quite a sight to behold. 

Looking West through the Rock Garden

Echium wildpretii  flowers close up.

Rock Garden circa 1914

Lower Gardens

Alpine House

Though significantly smaller in size than the Rock Garden, the botanics Alpine House displays a fantastic range of exotic alpine plants. Over 700 species from alpine regions around the world are housed in the gardens' propagation department though only around 20 will be displayed at any one time when they are deemed to be looking at their best. 

Alpine Display