Magnolia campbellii Hook. f. & Thomson

In its best forms this is a truly spectacular flowering tree. Potentially very tall and widely spreading, its huge flowers borne on bare branches alarmingly early in spring are typically a vivid rose-pink. While it grows well in mild, maritime areas such as southern and western Britain, this is a Hell’s Angel among magnolias, its fat hairy buds racing down the middle of the road to spring, and if frost is coming the other way it will not be the one to swerve. The high risk of buds and flowers being disfigured or effectively destroyed makes a good flowering season even more special, but also makes other, later flowering tree magnolias a less risky bet for all but the ambitious, optimistic gardener who has plenty of space and time to wait.

Among the larger, decisively tree-forming species of Section Yulania, M. sprengeri and M. campbellii are distinguished from M. dawsoniana and M. sargentiana by their upright rather than horizontal or drooping flowers. M. campbellii differs from the somewhat smaller M. sprengeri in its more or less ovate (as opposed to more or less obovate) leaves, and in its clawed tepals.

Magnolia campbellii was first described scientifically from the western end of its range, in NE India (Hooker & Thomson 1855), where it had brought itself to the attention of several colonial-era collectors. The specific epithet commemorates Archibald Campbell, a British East India Company official instrumental in getting Hooker and Thomson into Sikkim on their expedition of 1849–50. The many introductions to cultivation in Europe (especially Britain) began in this period, around 1865 (Bean 1981). As a wild plant, it has had a way of bringing out superlatives and passages of purple prose from those who encounter it in flower (e.g. Kingdon Ward 1930). Flower colour varies within these western forms; some pinks are more vivid than others, and white-flowered forms are the norm in most of its Himalayan range (Foster 1996). John Grimshaw (pers. comm. 2021) recalls that in a memorable talk about the Mount Everest expedition of 1953, attended while he was a student almost 40 years later, Sir Edmund Hillary showed a slide of Nepalese forest full of white-flowered Magnolia campbellii, which had evidently made a great impression on the mountaineers. It seems to be merely a historical accident that the type is pink flowered. Foster (1996) noted an individual with rich cream tepals within a white flowered Bhutan population, recording that ‘in the forest its effect was perhaps a touch yellower than that of Magnolia ‘Elizabeth’.

Things became complicated in the 20th century, when Magnolia mollicomata (differing primarily in its hairy pedicels) was described from a series of George Forrest’s specimens collected about 1000 km to the east, in the area where Yunnan meets Xizang (Smith 1920). Subsequently it has been treated as an infraspecific taxon within M. campbellii, either as subsp. mollicomata or var. mollicomata. Seed introductions from the same area quickly followed, most significantly F 24118, 24213 and 24214 of 1924 from the Shweli-Salween Divide, while Forrest’s 1914 gathering from the Dali area seems to have made only a small impact. Trees grown from these collections, along with their unhybridized seedlings, have a distinct set of features. Their tepals are a more subdued mauve-pink than the rose-pink of the western forms; flowers tend to have the ‘cup and saucer’ form prized by gardeners, with an outer whorl of tepals spreading (the saucer) while the incurving inner tepals remain upright (the cup); they flower later in the season than typical M. campbellii, but from an earlier age (10–14 years as opposed to 20–30); and there is a tendency for the crown to spread from an earlier age (Gardiner 2000).

However botanists concerned primarily with wild plants have increasingly rejected “mollicomata” at any level, beginning with Dandy (1928) just a few years after its description. The various characters which distinguish it in gardens vary independently across the wild range of M. campbellii, and when comparing wild specimens from across the range, “mollicomata” does not emerge as a discrete group (Spongberg 1976; Chen & Nooteboom 1993). Early (and ongoing) garden introductions focussed on the westernmost (“typical” campbellii) and easternmost (“mollicomata”) extremes of the range; the clear differences between them reflect this sampling bias. However, this does result in two distinct groups of plants in our gardens. These are long-lived trees, and vegetative propagation is usual, except when breeding new hybrids, so the difference persists. Gardeners need a name for these distinct plants, without being forced to place all garden clones in one or another mutually exclusive category (as is the way with varieties and subspecies), but naturalists should not be saddled with what for them is an unnatural, arbitrary distinction. Hence, M. campbellii Mollicomata Group is here defined (formal publication to follow) on the characters which make these plants distinct in gardens – see below. As with the Cultivar, a Group is intended to be used only for the naming of plants in cultivation (Brickell et al. 2016). Not all eastern forms are included within the Group, notably ‘Lanarth’ and other seedlings raised from F 25655. This collection was made further south than the collections which gave rise to Mollicomata Group, on the Salween-Kiuchiang Divide, Yunnan–Myanmar border, in 1924. These have previously been placed rather uncomfortably in subsp. mollicomata, although differing from those other collections in several ways.

Seed-raised M. campbellii takes up to 30 years before flowering begins. Selected clones are grafted or chip budded, usually onto Mollicomata Group rootstocks. These will generally flower in less than half the time, usually from 10 years. With the blooms being susceptible to frosting, which bleaches out the colour, it is important to site it well. A sheltered yet sunny site with adequate frost drainage is ideal. If a walled site is to be considered, a north wall should be chosen. Heat from a south-, or west-facing wall will cause buds to break too early. It is surprisingly wind tolerant, many trees in SE England suffering only from minor branch breaks in the hurricane-force winds of October 1987.

In Western cultivation, M. campbellii has been most widely tried in the British Isles and New Zealand. In Britain and Ireland, the majority of good specimens are in southern and western areas. Large examples include trees at Caerhays Castle, Cornwall (24.5 m × 333 cm, 2016) and at Castlelough House, Co. Tipperary, Ireland (21 m × 449 cm, 2010 – The Tree Register 2021) but they are many and widespread. Elsewhere in our European area the species can be grown in maritime France and the Low Countries. Climate change has made this dramatic species available to a wider range of gardeners than previously imagined: there are impressive specimens in many eastern gardens in Britain. It remains susceptible to spring frost and it is wise to choose later-flowering selections when planting M. campbellii away from the milder west.

In North America it is grown almost exclusively on the Pacific Coast, from San Francisco north to the Vancouver area (Dirr 2009); East Coast climates simply do not suit it. The first American specimen to flower was probably one in the Strybing Arboretum, San Francisco, in 1940, which still survives, flowering spectacularly each year (e.g. @sfbotanicalgarden Instagram feed, 5 February 2022). Now the San Francisco Botanical Garden, Magnolia campbellii remains an important feature of the garden’s Magnolia Festival in February each year. It has been in the North American nursery trade since 1937 but has never been a mainstream plant (Jacobson 1996). As in Europe, bud and flower damage is a problem in cold winters; during Vancouver’s severe 2008–9 winter, many large specimens at the University of British Columbia Botanical Garden suffered bud loss and even branch death (Justice 2009). It is extremely challenging to grow in the heat and humidity of the American East Coast, although it has flowered for Richard Figlar in South Carolina. It is much more widely grown in New Zealand, on both the main islands, having been in commerce with Duncan & Davies at least since 1915 (Royal New Zealand Institute of Horticulture 2020). In milder areas flowers are much less prone to frost damage than they are in Britain.

M. campbellii in its various forms has been an important parent of large-flowered hybrids.