High on hemp

Being driven through a village in the northern Netherlands I was idly staring out the window when I suddenly realised what I was seeing … so the next time we went that way, my host kindly stopped the car, chuckling at how the photos would seemingly reinforce the image of the Dutch being drug liberals.

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A hemp crop growing by the roadside in northern Netherlands. Photo: Sandra Simpson

However, what we were looking at wasn’t marijuana but hemp. What’s the difference? Hemp is farmed for its fibre, while marijuana is, well, still an illegal drug in a lot of places, despite the inroads of the medical variety.

Both plants have the same botanical name – Cannabis sativa – but levels of THC (tetrahydrocannabinol), which causes most of marijuana’s psychological effects are very low in hemp. “Hemp also has high cannabidiol (CBD) content that acts as THC’s antagonist, essentially making the minimal amount of THC useless,” according to the Ministry of Hemp website.

That website helpfully notes that the plants also look different, hemp being taller and thinner, are grown differently (hemp plants, as the photo shows, can be grown very close together), and have different climate needs.

And if any bright spark should plant some marijuana in amongst the hemp, thinking it won’t be spotted, it’s bad news – hemp pollen will destroy marijuana’s THC levels.

The Netherlands has long had a reputation for liberal drug laws – cannabis cafes and so on – but this has been changing since about 2005 and Dutch police hunt out cannabis crops, much as they do in New Zealand.

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Cannabis sativa – hemp. Photo: Sandra Simpson

The Dutch also have a long history of growing hemp, thought to be one of the world’s oldest crops. European navies – such as the Dutch, British and French – long used the fibre to make rope, paper, sails and clothing, while oil made from the seeds was used as a food and to fuel lamps.

In the 16th century, Henry VIII encouraged farmers to plant the crop to provide material for the Royal Navy – rigging, pennants, sails, and oakum were all made from hemp fibre and oil, while hemp paper was used for maps, logs and Bibles.

Unfortunately for hemp, politicians of the 1960s didn’t differentiate between it and marijuana and blanket bans came into place. In 1994 several farmers were contracted to grow 140ha of hemp in the Netherlands, making it the largest cultivation in the country for 60 years.

Since 2001 hemp has been grown under licence in New Zealand. Read an article about the experiences of Canterbury farmers. The law was once again reviewed in 2018 and Parliament’s webpage includes a useful Q&A.

The former New Zealand Green Party MP Nandor Tánczos famously wore a hemp suit to Parliament during his tenure (1999-2008) but these days the fibre is making a comeback, thanks to its (small g) green credentials.

Denim, Made Good is a collaboration between New Zealand online store Well Made Clothes and clothing label Good Studios to create a line of jeans made from hemp, which they say is one of the world’s most sustainable fibres.

“Hemp doesn’t need any insecticides or pesticides to grow and it requires 50% less water to grow than cotton. We’ve also used nickel-free domes, recycled zips, and paper labels, so every component of these jeans has as little environmental impact as possible.”

Update: A recent newspaper article has alerted me to the fact that hemp seed became legal to use in food products in New Zealand in November 2018. Apparently some 30 nations are producing industrial hemp including Australia, Spain, Austria, Canada and China.

Cameron Sims, of hemp specialist Plant Culture, says hemp is the most nutrient-dense seed in the world. Christchurch-based company The Brothers Green will from April 2019 supply hemp-based snack bars and hemp flour to all the South Island’s New World supermarkets.

Turning the air blue

The latest newsletter from the Royal NZ Institute of Horticultural contains a snippet on the agapanthus fertility and performance trials under way in botanic gardens in Auckland, New Plymouth, Wellington, Christchurch, and Dunedin.

The trials are looking for sterile or low-fertility agapanthus so gardeners can grow these popular plants without contributing to the ‘weediness’ of the surrounding landscapes.

Initiated by Auckland Botanic Gardens in collaboration with the nursery industry, Manaaki Whenua–Landcare Research, and others in the Agapanthus Working Group (established in 2012), the trials are looking to quantify the percentage of seed set among cultivars suspected of having low fertility.

White agapanthus flower – the tall-flowered plants come in blue or white. Image: Wikimedia

The plants, native to South Africa, are loved by gardeners for their toughness (easy to grow at the coast, drought tolerant), abundant flowers through the hottest part of summer, evergreen, and their dense root system which can help stabilise tricky banks. Unfortunately, the common tall, blue variety seeds prolifically and so constitutes a threat to native plants in natural landscapes.

In a 2016 paper for Landcare Research, Murray Dawson notes that agapanthus were first recorded as naturalised in New Zealand in 1952. The tall blue-flower plants produce a large number of seeds – and virtually all the seed germinates.

Councils in the Wellington area, for example, are encouraging gardeners to get rid of their common agapanthus – although warn it will take a strong back, a small digger or some serious poison to do the job, while Auckland Regional Council banned the plants in 2008.

Agapanthus ‘Thunderstorm’ has variegated foliage and grows to about 30cm. Image: Ian Duncalf

Four-year trials at Auckland Botanic Gardens and Lincoln University, which ended in 2016, showed that the dwarf-medium Agapanthus ‘Thunderstorm’ and ‘very dwarf’ A. ‘Agapetite’ were likely sterile, while the dwarf blue A. ‘Sarah’, dwarf white A. ‘Finn’, and dwarf dark blue with variegated foliage A. ‘Goldstrike’ have very low fertility.

The report concludes: “’Low-fertility’ is the most accurate term for claims made of most current cultivars.” Read the full report here (opens as a pdf).

Agapanthus ‘Thunderstorm’, bred by Kiwi Ian Duncalf, forms part of the Storm series for Anthony Tesselaar in Australia.

Agapanthus ‘Navy Blue’ growing in Alnwick Castle gardens in Northumberland. This is a deciduous plant. Photo: Sandra Simpson

In her 2017 book, The Wondrous World of Weeds (New Holland), Pat Collins writes that the indigenous people of South Africa grow the plants around their homes as they’re considered a magical aid to fertility and pregnancy!

“To soothe your feet after a long hike, weave the soft leaves into a slipper shape, put over the feet and relax. Has a silky smoothness that eases your aches.”

The root is also used by the Xhosa people in a medicinal way, even though the plants are toxic to humans. Note that the sap can cause severe ulceration of the mouth.

The striking flowers of Agapanthus ‘Twister’ – white, pink and blue – seen last year at Wollerton Old Hall in Shropshire, England. Another deciduous agapanthus. Photo: Sandra Simpson

‘Twister’, pictured above, was selected in South Africa in 2008 from the breeding programme of Quinton Bean and Andy de Wet and, after extensive trials in around the globe, the first plants were sold in 2013. Apparently, it was the first time the pair had released a plant into the international market – and they’ve had trouble keeping up with demand ever since!

In colder climates, the weedy tendency of agapanthus is dealt to over winter – or they’re grown in pots as house plants. The Royal Horticulture Society noted in 2017 that it had almost five pages of registered plants (but “the fact is that many are very very similar”.) Britain, where they’re also known as African lilies, even maintains a National Collection of Agapanthus.

Read more about plants available in New Zealand in this 2014 post.

Tree of the moment: Illawara flame tree

Brachychiton acerifolius, native to Australia’s east coast rainforests from Illawarra in northern New South Wales to Cape York, is suddenly making its presence known in gardens and on city streets – its common name gives some idea of the vivid scarlet-orange colour.

The flowering is enhanced by the fact that the tree is deciduous before flowering so the branches appear to be ‘burning’.

Illawarra flame tree in central Tauranga. Photo: Sandra Simpson

The Brachychitons are known in Australia as Kurrajong trees and the ever-knowledgeable Stirling Macoboy tells me (in his book) that all the Kurrajongs thrive in warm, dryish climates such as South Africa, California and the Mediterranean.

With our intense periods of rainfall, Tauranga may perhaps just about be on the edge of where the tree will do well in New Zealand. I have noticed several of the Illawarra flame trees planted as street trees in the city tend to produce their bell-shaped flowers only on one side of the tree (with leaves on the other half, it looks a bit strange) but reading more leads me to believe this is fairly common with seed-grown trees. Brachychiton acerifolius for retail now tend to be grafted.

Photo: Sandra Simpson

The flowers go on to produce large leather pods which hold corn-like seeds with nutritional value. Apparently indigenous Australians toasted and ate these seeds, used the inner bark for string and bandages, made tools and rums from the trunks and used the flowering as a weather indicator. If you’re collecting the seeds, it’s advised to wear gloves as they’re surrounded by irritant hairs (toasting got rid of these).

In the wild the trees are giants of the rainforest – up to 40m tall – but rarely make that height in cultivation where they grow to more like 10m. Trees grown from seed can take up to 10 years to flower … but it’s worth the wait.

Many Australian writers wax lyrical about the sight of an Illawarra flame tree flowering beside/in front of a jacaranda in bloom but to me it sounds like optical overload!

Father of Taxonomy

Each living thing on the planet – discovered by science – has a unique Latin name, a concept known as taxonomy with the modern version credited to Carl Linnaeus, a Swede who died 241 years ago today (January 10).

This Stockholm statue of Carl Linnaeus is surrounded by flowering plants. Photo: Sandra Simpson

Born in 1707, Linnaeus was a botanist, physician, and zoologist who trained at Uppsala University. From the 1740s to the 1760s he travelled throughout Sweden to find and classify plants, animals and minerals. At the time of his death in 1778 he was one of the most acclaimed scientists in Europe.

His father, Nils, was the first in his family line to adopt a permanent surname (the Scandinavian way was for each new generation to take the father’s first name as a surname – so Carl Oleson, was the son of Ole, and Carl’s son would be, say, Ole Carlson). Nils, a keen gardener, adopted the Latinate name Linnaeus after a giant linden tree (lime tree, ‘lind’ in Swedish) that grew on their farm.

Carl Linnaeus showed a love of plants from an early age and was fortunate to meet tutors who encouraged his study of botany. From 1730, and only a second-year student, he began lecturing – up to 300 people at a time! For a time he lived with the professor uncle of Anders Celsius, the inventor of a temperature scale. (Later Daniel Solander, who travelled with James Cook to the Pacific, was one of those who lived with Linnaeus in Uppsala.)

A bust of Carl Linneaus in Leiden University’s Hortus Botanicus, one of the oldest botanic gardens in the world. Linnaeus studied at Leiden University in The Netherlands for a time. Photo: Sandra Simpson

Linnaeus obtained his doctorate from Harderwijik University in The Netherlands (in two weeks!) and published his first thesis on taxonomy, Systema Naturae, in that country in 1735.

Back in Sweden in 1738, he helped found the Royal Swedish Academy of Science and in 1741 returned to Uppsala University as a Professor of Medicine, soon becoming responsible for the Botanic Garden which he renovated and expanded.

Philosophia Botanica, published in 1751, was a complete survey of his taxonomy system, as well as containing information on how to maintain a botanic garden. Species Planatum, published in 1753 in two volumes, is considered to be the starting point of the botanical naming we use today, while the tenth edition of Systema Naturae, published in 1758, is considered the starting point for zoological naming. 

Before Linnaeus, naming practices varied. Many biologists used long, unwieldy Latin names, which could be altered by anyone. For instance, the common wild briar rose was both Rosa sylvestris inodora seu canina and Rosa sylvestris alba cum rubore, folio glabro. The need for a reliable naming system became urgent when a huge number of plants and animals were brought to Europe from Asia, Africa, and the Americas.

Linnaea borealis (twinflower) pictured in Sitka, Alaska. Photo: Sandra Simpson

Ennobled in 1761, Linnaeus chose as part of his coat of arms the twinflower, one of his favourite plants, which was renamed Linnaea borealis in his honour. Although he has been described as one of the most arrogant men in the history of science – he apparently liked to say “Deus creavit, Linnaeus disposuit” (God created, Linnaeus organised) – he never named a plant after himself .

During his life Linnaeus named nearly 8,000 plants, as well as many animals and gave the scientific designation for humans: Homo sapiens. Linnaeus perhaps had fun with his plant naming – the most beautiful plants were often named for his supporters, while his detractors often supplied the names of common weeds or unattractive plants!

His wife, Sara, survived both her husband and their elder son, who had kept his father’s collection despite an approach by Joseph Banks to buy it. When Sara contacted Joseph Banks after her son’s death in 1783 he was no longer interested. Instead, a 24-year-old medical student bought it – and 5 years later James Edward Smith founded the Linnean Society of London, the world’s oldest extant biological society.

In 2007 Kennedy Warne wrote a piece for NZ Geographic to mark the 300th anniversary of Linneaus’ birth, which also reflects on the future of his system. Read it here.

This statue of Linnaeus is in the Skansen Open-Air Museum rose garden on the island of Djurgården in Stockholm. Photo: Sandra Simpson

Our native plants: Kaka beak

The kaka beak (Clianthus), an endangered New Zealand native shrub, gets its name from the shape of the flower resembling the beak of the kaka, a native parrot. There are actually two red-flowered types (C. puniceus and C. maximus), plus a white-flowered variety.

Kaka beak generally flowers from early spring, although can flower year round. This was taken in Wellington’s Botanic Gardens in January. Photo: Sandra Simpson

A 2005 survey found only 153 C. maximus plants in the wild in the North Island’s East Coast and northern Hawke’s Bay, and under threat in all places from browsing animals, including sheep, cattle, deer and pigs. By 2013 that number had dropped to 109. The plants are not found naturally in the South Island.

The Forest Lifeforce Restoration Trust has come up with a novel way of trying to get more plants into the wild – packing shotgun cartridges with shot and kaka beak seed, going up in a helicopter and firing the cartridges into spots inaccessible to browsers!

As you see from the foliage, they’re part of the pea family so fix their own nitrogen and can grow in relatively poor soils. The spectacular clusters of flowers attract nectar-loving birds.

Gardening with NZ Plants, Shrubs and Trees (Collins, 1988) says it was one of the few plants pre-European Maori grew simply for its beauty – or possibly for flowers to feed caged (speaking) tui. The Maori name, Kowhai ngutu-kaka, literally means parrot-beaked kowhai (Sophora, another member of the pea family). 

Photo: Sandra Simpson

Lawrie Metcalf writes in The Cultivation of NZ Trees and Shrubs (Raupo, 2011) that kaka beak was introduced into gardens in England in 1831 with the first plants selling for the princely sum of £5. Oddly, given its endangered status in the wild, plants are widely available in garden centres in New Zealand with ‘Kaka King’ the trade name for C. maximus.

Lawrie also notes that while being shown around Sissinghurst Castle Garden – by Vita Sackville-West, no less – they came upon a C. puncieus ‘Albus’ growing in an urn on a pedestal. “Its position at eye level allowed the plant to be appreciated fully, and its situation in the light shade of some deciduous trees really highlighted the beauty of its white flowers.”

In cultivation C. maximus can grow up to to about 4m tall (6m in the wild) and C. 
puniceus about half that size. Common knowledge has it that they tend to be short-lived in the garden (2-4 years), although a prune after flowering will stimulate new growth and keep the plant going longer (hedgecutters are okay). However, Fiona Eadie, head gardener at Larnach Castle on the Otago Peninsula, says in her 2008 book, 100 Best Native Plants (Godwit), that a specimen there lasted 25 years surviving “moderately severe frosts and many a snowfall”. She emphasises a dry site above all and vigilance with chewing and sucking insects.

Otari Wilton’s Bush in Wellington has trained a Clianthus maximus against a trellis – one way of ensuring the flowers are shown off. Photo: Sandra Simpson

Glyn Church reports that he grew them well in the full blast of Wellington’s winds which seemed to keep pests at bay too.

The Plant Conservation network listing suggests siting plants in fertile, well-drained, sunny sites free from surrounding shrubs to combat pest and disease problems. Galls, caused by a mite, should be removed as soon as they appear.