Podocarpus macrophyllus (Thunb.) D. Don

Podocarpus macrophyllus has a broad distribution from the eastern edge of the Tibet-Qinghai Plateau through warm-temperate to sub-tropical parts of China, Myanmar, Vietnam and Japan, as well as the island of Taiwan, primarily below c. 1000 m asl (Farjon 2017; Debreczy & Rácz 2011)). With such a distribution it should come as no surprise that this is a species whose greatest horticultural potential may be realised outside our proper study area, in areas with hot summers and mild winters, such as the southern states of the USA, mediterranean and subtropical regions of central and South America, southern Africa, Australia and New Zealand. In many of these areas, most especially the southern USA, P. macrophyllus is a significant and widely grown ornamental while for centuries, perhaps millennia, it has also been extensively planted throughout its native range (especially var. maki – Farjon 2017). Numerous cultivars have been selected, including many with brightly coloured new growth, while others are spreading or compact. They will tolerate clipping and the species is often used as a hedging or screening plant, but when allowed to grow naturally forms a small, reasonably narrow tree.

In a genus already difficult to characterise in a work focused on temperate areas, P. macrophyllus may be one of the more difficult species to discuss. Had this account been written twenty years ago, at the start of the new millennium, it would have been easy to dismiss this species as half-hardy, suitable only for the mildest gardens on the fringes of our study area, but now it seems set to become one of the horticultural beneficiaries of climate change. In the last twenty years more adventurous growers have tested P. macrophyllus beyond its traditional limits and their experiments have often met with success. Of course, particularly cold winters are still an enemy, and cool summers can drastically hold back growth, but the emerging trend for prolonged, warm summers in parts of north-west Europe is making P. macrophyllus less of a gamble with each passing year. It seems likely that certain clones in general circulation are hardier and more vigorous than others, but these have not yet benefited from sufficient attention to enable meaningful comparisons to be made here.

P. macrophyllus sits at the centre of one of the many vexatious species complexes in this genus: in its orbit are numerous entities including its widely accepted var. maki (most reliably distinguised by its wider leaves, but there is overlap with var. macrophyllus – Farjon 2017). Var. maki is probably the commonest form of the species in general cultivation in the west and most of the early introductions likely belonged here (Grimshaw & Bayton 2009). Several late 20th century introductions, from relatively high altitude in western China, have been made under the names P. chingianus and P. forrestii, names whose position and rank, and indeed any validity at all, is subject to ongoing debate. Certainly plants labelled P. chingianus and P. forrestii are strikingly similar to P. macrophyllus (var. macrophyllus) and technical literature suggests that they fall within the accepted variation of this species (indeed, P. chingianus was originally described as a variety of P. macrophyllus but later elevated to species rank, while conifer specialists Aljos Farjon (2001, 2017) and David de Laubenfels (1985) both consider P. forrestii synonymous with P. macrophyllus var. macrophyllus and this view is adopted here. Besides the taxonomic difficulties inherent in this genus (discussed in the genus article) the long use of P. macrophyllus (especially var. maki) and perhaps some of its close relatives in gardens and forestry within and near to its native range, from where birds will have dispersed it yet further, has muddled the picture considerably; in some areas the ‘nativeness’ or otherwise of populations is not at all clear, compounding the difficulties facing researchers. In time these satellites will probably come to be more widely regarded as part of a broad interpretation of P. macrophyllus. We include them in synonymy here but discuss the history of these names, and introductions made under them, under appropriate subheadings below. P. nakaii is another P. macrophyllus lookalike endemic to mid- to high-elevations in Taiwan; we give this taxon the benefit of the doubt and discuss it separately. P. neriifolius overlaps with P. macrophyllus in south east Asia but is quite distinct (Debreczy & Rácz 2011).

It is probable that most of the cultivars discussed here belong to var. maki but we follow the authoritative Encyclopaedia of Conifers (Auders & Spicer 2012) in not distinguishing them to infraspecific level. Indeed, most cultivated P. macrophyllus within our area are probably var. maki (except those introduced as P. chingianus and P. forrestii) but few labels and databases make the distinction; the various characters and dimensions used to distinguish them are all variable, the most reliable are cited in the key below.

Podocarpus chingianus

Ostensibly distributed in Jiangsu, Zhejiang and perhaps Sichuan, this entity is poorly understood as a wild plant. It was originally described as a variety of P. macrophyllus in 1958, based on a single collection from Zhejiang deposited at the Arnold Arboretum herbarium. Hu elevated it to species rank in 1964 based on study of additional material; he described its habitat as secondary woodland and shrubland over an inferred altitudinal range of 0–1000 m asl (Farjon 2017). Hu’s treatment has generally been followed ever since, although it was treated as a P. macrophyllus cultivar in the Flora of Zhejiang Province (1993); its occurrence in Sichuan has never been confirmed (Farjon 2017). John Silba distributed material of known wild origin, traceable to Zhejiang, to multiple institutions in the 1990s. Plants were received at the Royal Botanic Garden Edinburgh in 1995 simply marked ‘C-5526’; the following year a rooted cutting deriving from the same collection arrived via Pinetum Blijdenstein. Plants from these introductions survive under glass at Edinburgh and outdoors at Bedgebury National Pinetum where a single plant was sent in 2003 when it was 80 cm; it was 1.6 m in 2010, after which it was severely hampered by the extremely cold winter of 2010–11. It had recovered to only 1.7 m by 2018 (pers. obs.) and five years later continues to limp along (D. Luscombe pers. comm. 2023). A plant accessioned at Tregrehan in 1995 had made a 4 m tree by 2017 (Smith & Hudson 2017). The UK’s National Trust has distributed cutting-raised material several times through the 2010s. All these plants are rather upright in habit with conical-columnar crowns.

Podocarpus forrestii

Described from Forrest collections gathered on the Tali Shan in August 1906 (F 4665). Forrest’s notes, including from subsequent expeditions, describe shrubs to c. 3 m growing in scrub and dry places at 2400–3000 m asl (herbarium specimen data). There is no indication that Forrest introduced living material and no wild plants have been reported since (P. Thomas pers. comm. in Grimshaw & Bayton (2009)). Material was introduced under this name in the early 1990s from a group of cultivated trees growing in and around the First Middle School in Dali. Maurice Foster recalls two plants growing in the school grounds, one distinctly shrubby and one more tree-like (M. Foster pers. comm. 2022) one male and one female. Various western collecting teams have sampled these accessible plants, including the Chungtien, Lijiang and Dali (CLD) expedition in 1990 (CLD 1565 and 1566B) material from which remains under glass at the Royal Botanic Garden Edinburgh, and the Alpine Garden Society expedition of 1994 under ACE 2543A (the male plant, as cuttings) and 2543B (the female, as a few seeds and cuttings). ACE 2543A is represented in several UK collections, including Tregrehan, where despite the mild, moist climate, growth has been extremely slow: dispatched there from Edinburgh in 2002 when 70 cm tall, by 2022 it remained only 1.5 m (pers. obs.). Two plants from ACE 2543B survived at Bedgebury, Kent: in 2010 when these were 50 and 55 cm, with growth then averaging just 2 cm per year (pers. obs.); in early 2023 they remain stunted, small, disappointing plants (D. Luscombe pers. comm.). A better plant grows in Maurice Foster’s arboretum at White House Farm, also Kent; this was approaching 2 m and growing vigorously in June 2022 (pers. obs.).