My mahonia is looking pretty cheerful at the moment: as good a reason as any to find out a bit more about it – including, I hope, the reason for its flowering in the coldest months of the year, when any self-respecting insect pollinator is either (a) dead; (b) in its larval stage; or (c) hibernating somewhere warm and cosy, such as the grooves in the frames of my sash windows. (Having said that, in fact on 8 January it was sufficiently warm that bees were buzzing all over my bush).

A bee on the flowers in early January 2017.

The genus Mahonia consists of about 70 (s0me argue for up to 200) species and is widely spread across northern Asia and America. It first came to notice in the form of Mahonia aquifoilum, the Oregon grape, one of the specimens gathered by the Lewis and Clark expedition to the source of the Missouri and the Pacific between 1804 and 1806, and rapidly became a popular ornamental plant (introduced to Europe in 1822, and now regarded as invasive in Sweden and Austria), not least because of its bright winter flowers. Asian varieties, including Chinese mahonia (Mahonia fortunei, named by John Lindley) and Mahonia japonica (named by Thunberg) were discovered later.

Mahonia flowers.

I am embarrassed to say that I’m not actually sure what variety my mahonia is: it was planted about 25 years ago, and at the time Mahonia x media ‘Charity’ was all the rage, so it might be that. My motive in placing it in a rather shallow, poor-soil niche on the curtilage (as the City Council bin people like to call it) of the Hedgehog Estate was that I had a little pillar cypress there that got pulled up, dragged down the street and dumped a couple of times – and nobody, however drunk or otherwise intoxicated on their way to the station, pulls up a mahonia lightly.

Nobody tries to pull it up any more …

It has flourished in these unpromising conditions, and is now over 5 meters high and nearly 80 cm round its rather nobbly girth at base.

The trunk of my mahonia, surrounded by fallen petals.

It submits uncomplainingly to its branches being lopped if they grow out too far across the garden path or the pavement, and its wood fibre is very soft, and a startling yellow colour which however does not bleed sap. It flowers from winter into spring, and its profuse, purple, bloom-covered ‘grapes’ later cause riots among competing blackbirds.

The fruit of Mahonia aquifolium.

The fruit is theoretically edible by humans, but comes with a health warning: ‘can cause vomiting, lowered blood pressure, reduced heart rate, lethargy, and other ill-effects when consumed in large quantities’. (This doesn’t apparently apply to blackbirds, but is caused by the compound berberine, reminding us that the mahonia is a close relative of the berberis and falls inside the shrub family of the Berberidacaea: the closeness gives rise to some taxonomic issues as to which species are in which genus.)

A mahonia in the Winter Garden at Cambridge University Botanic Garden.

Mahonias were given the name by Thomas Nuttall in 1818. It honours one Bernard McMahon (or M’Mahon, 1775–1816), author of the best-selling American Gardener’s Calendar, first published in 1806. He had arrived in the United States from Ireland in 1796, allegedly to avoid political persecution (not implausible after the failed French invasion of 1796 and the consequent rounding up of the leaders of the United Irishmen). By 1802 he had established a seed and nursery business in Philadelphia, publishing shortly afterwards a catalogue of ‘garden grass, herb, flower, tree and shrub-seeds, flower roots, etc.’ containing 720 varieties of plants and seeds; his ‘how-to’ Calendar continued to appear, with modifications, up to 1857.

The title page of the first edition.

The Calendar is revealingly described in its subtitle as ‘adapted to the climates and seasons of the United States’. It is ‘a complete account of all the work necessary to be done in the kitchen-garden, fruit-garden, orchard, vineyard, nursery, pleasure-ground, flower-garden, green-house, hot-house, and forcing frames, for every month in the year’. It borrows from British models, notably Philip Miller’s Gardener’s Dictionary; and J.C.Loudon, no mean instructor in horticulture himself, rather sniffily remarked in 1826 that ‘We cannot gather from the work any thing as to the extent of American practice in these particulars’ – the implication presumably being that at this stage the number of hot-houses and forcing frames in the United States was limited.

Indeed, when William Cobbett published his The American Gardener
A Treatise on the Laying-Out of Gardens, on the Making and Managing of Hot-Beds and Green-Houses, and on the Propagation and Cultivation of the Several Sorts of Vegetables, Herbs, Fruits and Flowers in 1821, his purpose was ‘to cause the art of gardening to be better understood and practised than it now is in America’. He makes no mention in his preface (dated 1819) of any earlier publications offering advice, and indeed is rather scornful of immigrant ‘professional’ gardeners: ‘Every man, who can dig and hoe and rake, calls himself a Gardener as soon as he lands here from England … But as to the art of gardening, they generally know nothing of it.’ Did he have anyone in particular in mind?

McMahon’s publications, however, found favour with Thomas Jefferson, at that time President of the United States, Founding Father, and distinguished horticulturalist whose gardens at Monticello were famous across Europe as well as America. Jefferson apparently followed the Calendar’s guidance on planting, and obtained seeds and plants from its author. It is even possible that the layout of Monticello itself was influenced by McMahon’s essay in the Calendar on landscape design, which favoured a Reptonesque, naturalistic style.

McMahon’s appeal to Americans to appreciate the beauty and utility of their country’s native plants, rather than seeking to import European ‘exotica’ which might not thrive in the climate or the soil, would also have struck a chord with the President, and it is perhaps not surprising that he was entrusted with some of the botanical materials brought back by Lewis and Clark in 1806. However, McMahon may well have been exasperated by his inability to exploit these new finds: in Jefferson’s view, they were all government property, and as well as their being raised in quarantine-like conditions, there were also restrictions on naming and publicising the plants.

In 1808, McMahon bought 20 acres of land near Philadelphia to expand his nursery: he named it Upsal, in tribute to Linnaeus, whose binomial system he had enthusiastically adopted, and, run by his widow and son, the business remained famous after his death. (There is an attractive description of it here.) He did not acquire his own binomial in his lifetime, but Nuttall, who frequented his nursery, obviously considered him worthy of one of the most spectacular and popular new discoveries of the time.

Caroline