Manuka, Leptospermum scoparium

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Leptospermum scoparium

Manuka, Leptospermum scoparium, with solitary wasp Sapyga quinquepunctata (May 2017).

Yesterday I walked around the garden, noting what was in flower. In short, not much: stalwarts like Erysimum ‘Bowles’ Mauve’, Erigeron karvinskianus, Winter Heliotrope, Fuchsia microphylla, Coronilla, daisies in the lawn and some trailing Lobelia plants in a sheltered place that have escaped the frost. But, by our south-facing living room wall, our Leptospermum scoparium (Manuka or New Zealand Tea Tree) has started to flower. It will continue to flower into spring, reaching its peak in late May and June.

Leptospermum scoparium is native to Australia and New Zealand, and is a member of the family Myrtaceae, along with the Mediterranean shrub Common Myrtle, Myrtus communis, and well-known Australian plants such as the gum trees, Eucalyptus, and bottlebrushes, Callistemon. The family also contains several spices: the Clove, Syzygium aromaticum, a native of Indonesia, and the Guava, Psidium guajava,  and Allspice, Pimenta dioica, both from Southern and Central America. Bog Myrtle, Myrica gale, a British native, is not a relative – it is in the family Myricaceae.

Leptospermum scoparium is thought to have originated in Australia and then spread to New Zealand, where it is now much commoner. It is a shrub or small tree, typically forming scrub 2 – 5 metres (7 – 16 feet) tall, but capable of growing up to 15 metres (nearly fifty feet). It has small, prickly leaves and pink or white flowers with five petals. It can form dense scrub and is often one of the first species to regenerate on land that has been cleared. It was first grown in the British Isles in 1772 and escaped into the wild on Tresco (Isles of Scilly) in 1935.

I bought my Leptospermum scoparium from Dover Farm Nurseries in Briston in North Norfolk in the spring of 2015. The plant was covered in a mass of flowers and it was an impulse buy. I soon found a space for it underneath the living room window, in a sheltered and sunny spot. I added homemade compost to the poor, sandy and rubbly soil before I planted it and it turns out I had chosen the ideal conditions for it. Leptospermum is hardy to about -5 degrees Celsius (USDA Hardiness Zones 9 -10, equivalent to RHS Hardiness Rating H2 – H3). It seems very happy next to the house, but I remember seeing lots of dead Leptospermum and Callistemon plants after the cold winters of 2009 – 2010 and 2010 – 2011, so I am aware I may have to cover it in severe frosts. In a colder climate, Leptospermum can be grown in a pot, in ericaceous compost. Avoid peat because of the environmental damage its extraction causes – I use alternatives such as wool-based composts.

There are lots of cultivars of Leptospermum, and L. scoparium is not the only species grown. Flower colour ranges from white to deep red-pink and there are dwarf forms as well (L. scoparium nanum). Burncoose Nurseries has photographs and descriptions of many of these. The variety ‘Red Damask‘ is a bit hardier, and is given RHS hardiness rating H4 (hardy to -10 degrees Celsius), but its flowers are partly double and I don’t particularly like them. My own cultivar was labelled ‘Lambertii‘.

Leptospermum means “thin leaves”. Manuka is the Maori name for Leptospermum scoparium. Other names include New Zealand Tea-tree, but tea tree oil comes from a different species, the Australian plant Melaleuca alternifolia, also in the Myrtaceae.

Honeybees make Manuka honey from the nectar of Leptospermum scoparium. The honey is claimed to have antibacterial properties and is a fashionable health food. It has a very distinctive taste, described as “florid, rich and complex“. I like the flavour, though whether the honey is quite worth the high price is debatable. There have been cases of adulteration of Manuka honey and beehives in New Zealand have been damaged, presumably by competitors. News of honey wars have been reported in British newspapers in recent years and there is an ongoing dispute between New Zealand and Australia over the trade marking of the name “Manuka”.

Meanwhile, in the UK, the Tregothnan Estate in Cornwall is growing Manuka and uses the leaves to make a type of tea. (Manuka tea is described as “refreshing” by the Plants For A Future website, though the leaves need to infuse longer than ordinary tea. On the Camper Mate website Adam Hutchinson recorded his experience of making some from fresh leaves, but “sadly, it tasted terrible”.)

Tregothan also produces Manuka honey on a very small scale, but with just twenty 420g jars from the 2016 season, selling at £225 each I don’t think this is any threat to Australian and New Zealand honey producers.

In our own garden, honeybees and bumblebees are attracted to the flowers, along with solitary bees such as the Short-horned Yellow-face Bee, Hylaeus brevicornis and the solitary wasp Sapyga quinquepunctata. The latter more normally visits thyme flowers, and is on the lookout for its prey, Mason Bees (genus Osmia).

Bloody Crane’s-bill, Geranium sanguineum

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Geranium sanguineum

Bloody Crane’s-bill, Geranium sanguineum, and Meadowsweet, Filipendula ulmaria, growing on a road verge in Cumbria.

It is six years since I started this blog, and during that time I haven’t written about any of my favourite groups of plants, the crane’s-bills (genus Geranium, in the family Geraniaceae). It is time I made amends.

We have about a dozen species of Geranium in our garden, including cultivated varieties and “weeds”, like Herb Robert (Geranium robertianum) and Shining Crane’s-bill (Geranium lucidum), that I allow to grow and self-seed, pulling out any that are in the wrong place. Bloody Crane’s-bill, Geranium sanguineum, is one of my favourite crane’s-bills.

I first encountered Bloody Crane’s-bill in The Burren in Ireland, where it grows in gaps (grikes) in limestone pavements. Then, when we bought our first house in Norwich, it was growing in the back garden, and we moved some to our current garden when we moved here nearly five years ago. Since then I have seen Bloody Crane’s-bill on low cliffs along the Northumberland coast and on roadsides in Cumbria. My experiences of the plant tie in with the description of the plant’s distribution in the Online Atlas of the British and Irish Flora: it can be found in grassland, rocky woodlands and on coastal cliffs, where it prefers base-rich soils, but it can often be found as a garden escape. Bloody Crane’s-bill also grows in other parts of Europe and Asia, as far north as southern Finland. And in America – according to Missouri Botanical Garden, Geranium sanguineum is “perhaps the most common species of geranium grown in the U.S. today”.

Bloody Crane’s-bill is a clump forming perennial with deeply divided palmate leaves. The flowers have five overlapping petals and appear from May to August, with their peak in June and July. In the commonest form of the plant these are magenta, ageing to a purplish-blue. According to Richard Mabey (Flora Britannica p272), the name “bloody” and the specific name “sanguineum“, which means the same, originally came from the colour of the plant’s stalk-joints. The flower stalks, seed capsules and leaves also turn red in autumn. The First Nature website says that it is the colour of the stalks and seed capsules that give rise to the name, while Wikipedia suggests that it may be the autumn leaf colour.  The specific name “Geranium” and the English name “Crane’s-bill” (also written “Cranesbill”) both refer to the shape of the plant’s seed capsule.

When I selected plants for Grapes Hill Community Garden in 2011, I ordered several Geranium sanguineum. I was a little surprised when these produced flowers with crinkled pink petals, rather than magenta. I discovered we had bought Geranium sanguineum ‘Striatum’, Striped Bloody Crane’s-bill. It was actually a pleasant surprise: it is a very pretty flower. I now grow both forms in our back garden. I hope to visit Walney Island in Cumbria one day to see G. sanguineum ‘Striatum’ growing in the wild. (Its older name of Geranium sanguineum var. lancastrense is sometimes used by gardeners and refers to its place of origin – before boundary changes in 1974 Walney Island was part of Lancashire. 

Nurseries such as The Plantsman’s Preference in South Norfolk stock many other varieties. I have also tried G. sanguineum ‘Max Frei’, which has magenta flowers but is a more compact plant, suited to banks and rockeries.

Geranium sanguineum is a superb garden plant. It is good ground cover but it isn’t invasive. Clumps can be split every few years and new plants can also be grown from seed. The RHS and Gardeners’ World websites give advice to growers. I have grown Bloody Crane’s-bill in semi-shade and sunshine, on loamy soil and sandy loam. The ideal growing medium is “moist but well drained“, if such a soil exists.

For more photographs of Bloody Crane’s-bill, I recommend the Wildflower Finder and Finnish NatureGate websites.

One very good reason for growing Geranium sanguineum is its wildlife value, as the flowers are attractive to a range of solitary bees. In our garden last summer the flowers were visited by several species, including the Patchwork Leafcutter Bee (Megachile centuncularis), the White-jawed Yellow-face Bee (Hylaeus confusus), the Large Narcissus Hoverfly Merodon equestris, the Blue Mason-bee (Osmia caerulescens) and Small Scissor Bee (Chelostoma campanularum).

Chelostoma campanularum

Small Scissor Bee, Chelostoma campanularum, on Geranium sanguineum flower. June 2017.

Although Bloody Crane’s-bill isn’t thought to be poisonous, it isn’t considered to be edible either. The Plants For A Future website doesn’t list it but it has an entry for its relative Meadow Crane’s-bill, Geranium pratense. Under “edible uses” it says “none known”.

Honey Bush, Melianthus major

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Honey Bush, Melianthus major

Honey Bush, Melianthus major, in Ventnor Botanic Garden.

It is just over a year since we replaced the raised bed in our front garden and the plants have already bulked up and settled in. The Honey Bush, Melianthus major, in the centre of the bed, is looking particularly lush and put on a big growth spurt in the early autumn.

I first encountered Melianthus major at the Priory Maze Gardens at Beeston Regis, near Sheringham in North Norfolk, a few years ago. I was struck by its spectacular glaucous foliage and, brushing against its leaves, its scent of peanut butter. After that I started to notice it growing elsewhere, such as a front garden I often walk past on Earlham Road in Norwich and in the lovely Ventnor Botanic Garden on the Isle of Wight. Here, in a mild climate and a very sunny spot, the plants were flowering and setting seed.

Melianthus major is a native of South Africa, although it has been introduced into India, Australia and New Zealand. It can grow to 2 to 3 metres (7 – 10 feet) tall within the space of one season and plants can be at least as wide as they are tall. Melianthus major has pinnate, blue-green leaves with serrated edges, each of which can grow over a foot (30 centimetres) long. It is a member of the family Melianthaceae.

Melianthus major can stand a slight frost (hardiness H3), down to about -4 degrees Celsius, and on days when the temperature dips just below freezing point, our plant droops, but then recovers. In colder weather, the stems can die back completely, but the roots are pretty hardy and the plant will grow back in the following year. In South Africa Melianthus plants sometimes die back during summer droughts but the autumn rains encourage the rootstock to regrow and the plants put on lush growth in the winter rainy season. Gardeners often cut back their Melianthus major plants to keep the plant smaller and neat. This is best done in spring, as the old foliage protects the plant from frosts.

In a warm, sheltered spot where the foliage hasn’t been cut back, Melianthus major will produce racemes of flowers in spring. These are 30 – 80 centimetres (12 – 31 inches) long. The flowers are almost the colour of dried blood – described as dark maroon, brownish crimson to brick red or dark red. They are full of nectar. In South Africa they are visited by bees and by nectar-feeding birds, such as sunbirds, white-eyes and red-winged starlings.  The flowers are followed by green seedpods. Linda Cochran grows Melianthus major in Port Ludlow, Washington, in the United States and her blog has some good photographs of the flowers and seedpods. The Plants Africa website has more detailed photographs of the flowers and describes their structure.

Melianthus produces large amounts of black nectar, which can literally drip from the flowers (and stain clothing). The scientific name Melianthus major means “large honey flower” and, as well as ‘Honey Bush’, English names for the plant include ‘Honey Flower‘, ‘giant honey flower’ and ‘touch-me-not’.

I like to squeeze Melianthus leaves for the peanut butter aroma, but not everyone likes the smell. The name ‘touch-me-not’ comes from the smell of the leaves and is a translation of the Afrikaans common name for the plant, kruidjie-roer-my-nie, which means ‘touch-me-not-herb’. Perhaps the smell is stronger in a hot climate?

Although Melianthus major smells of peanut butter, don’t be tempted to nibble the leaves, for the plant is poisonous. According the Plants For A Future website, the root is the most poisonous part of the plant. The nectar is very sweet and is sometimes eaten. Thomas C. Fuller and Elizabeth McClintock write in “Poisonous Plants of California” that honey from Melianthus flowers “is considered toxic” but Plants Africa says the plant “is said to produce good honey“.

In South Africa, Melianthus is used in traditional medicine. According to Plants Africa: “The leaves are used to make poultices and decoctions to treat septic wounds, sores, ulcers, boils, abscesses, bruises, backache, painful feet and rheumatic joints. The roots and leaves are used to treat snakebite, or taken in very small doses as a tonic. It is also used to make a gargle for sore throats and mouth infections. Dried flowers and leaves can be used to keep insects out of cupboards”. The plant is usually avoided by livestock because of its smell.

Melianthus major contains bufadienolides, (named after the toad, Bufo), cardiac glycosides that increase the output force of the heart and decrease its rate of contractions. (Other poisonous plants that contain cardiac glycosides include the Foxglove, Digitalis purpurea, and the Lily-of-the-Valley, Convallaria majalis.)

But don’t let the fact that it is poisonous stop you growing this magnificent plant.

Melianthus major likes a sheltered sunny spot and reasonably well drained soil. Once established, it copes well with drought, though my plant wilted very quickly in the couple of months when it was in a pot, prior to being planted in the raised bed.

If you want to produce more plants, Melianthus major is easy to raise from cuttings taken in spring and grown in a greenhouse, or from seed. The plant appears to have few pests, though whitefly and red spider mites could be a problem in a greenhouse and Cool Tropical Plants mentions that older leaves can be attacked by aphids.

Melianthus comosus is a more compact relative, whose leaves have attractive copper-gold undersides. It also comes from South Africa and is said to be very suited to British gardens.