Fatsia Decne. & Planch.

Fatsia is a poorly diversified genus of only three species of evergreen shrubs: F. japonica from Japan and South Korea, F. polycarpa from Taiwan, and F. oligocarpella Koidz. which is endemic to Japan’s Bonin Islands (Plants of the World Online 2025). This is one of rather few genera distributed in both continental and oceanic islands. Chiang et al. (2014) suggest that F. oligocarpella and F. polycarpa likely diverged from F. japonica (with F. polycarpa splitting about 0.51–0.79 MYA, and F. oligocarpella 0.89–1.38 MYA), in a scenario of post-glacial southward migration from parts of mainland southern Japan that had served as refugia.

The first species to be introduced to the west was Fatsia japonica, which was first described to science as Aralia japonica in 1784, as Aralia japonica by the Swedish botanist Carl Peter Thunberg in his Flora Japonica (Thunberg 1784). It was soon differentiated from Aralia by virtue of its valvate corollas and the genus Fatsia was described to accommodate the species by Decaisne and Planchon in 1854, creating the combination Fatsia japonica (Decaisne & Planchon 1854; Bean 1981). ‘Fatsi’ was believed to be the Japanese common name, but this may have been an obsolete or misrendered version of ‘yatsude’, meaning ‘hands with eight fingers’, referring to the shape of the leaves (Prain 1915; Blackburn 1948).

Fatsia sits within the Asian Palmate Group (AsPG) of the Araliaceae family, a highly diverse clade primarily from Asia, uniting genera with palmate venation, lobing or divisions (Plunkett et al. 2018). The lack of distinct morphological characters, coupled with difficulty obtaining a clear evolutionary picture through DNA sequencing, has resulted in a muddled history of taxonomy and excessive synonymy within Araliaceae; newer sampling techniques continue to display phylogenetic discordance (Plunkett et al. 2018; Kang et al. 2023; Chiang et al. 2014). Recent phylogenetic analyses have recovered the Fatsia-Oreopanax clade, which includes Sinopanax formosanus, as a sister clade either to the Hedera-Merrilliopanax clade or the Brassaiopsis-Trevesia clade, within an internal polytomy of AsPG lineages; it is suggested that the incongruent topologies are consistent with ancient hybridization in the origin of the AsPG (Gallego-Narbon et al. 2025; Valcarcel & Wen 2019; Chiang et al. 2014; Gallego-Narbon, Wen & Valcarcel 2022; Li & Wen 2016).

Fatsia species are unlikely to be confused with the more abundant species of Oreopanax (148 species), as the latter are rarely cultivated in the temperate northern hemisphere, hailing as they do from the neotropics and not being reliably hardy (Plunkett et al. 2018; Smith 2014). There are a broad range of leaf-shapes within Oreopanax, including palmate and palmately compound, and whilst some of these may bear resemblance to Fatsia (e.g.. O. peltatus, O. dactylifolius), the flowers are different in their ultimate units which are capitula rather than umbellules; they also lack pedicels, whereas Fatsia have relatively long pedicels. Sinopanax formosanus has densely ferruginous tomentose undersides to its leaves, which have fewer, more coarsely dentate lobes than Fatsia, short pedicels and only 3 bracts per flower, the ultimate unit being a capitulum (Plunkett et al. 2018). In other topologies, the Oplopanax clade has been reported as a sister clade to Fatsia (Kang et al. 2023); however, these are easy to differentiate due to the needle-like prickles which cover Oplopanax (Bean 1981).

In appropriate temperate regions, Fatsia japonica and F. polycarpa are commonly cultivated as architectural foliage plants for exotic, jungle-style or subtropical planting schemes. Although several attempts have been made to grow it, and it was listed in the RHS Plant Finder in 2010–11, F. oligocarpella is currently not known to be in cultivation outdoors in temperate regions (Collings 2024), though it has been in recent decades (M. Griffiths pers. comm. 2026). It is not treated in this account.

Both Fatsia japonica and F. polycarpa are useful plants for difficult positions, being shade-tolerant and unfussy about soil, though neither will tolerate waterlogged or very dry conditions; they perform best in a fertile, moist soil with good drainage (Big Plant Nursery 2025). As woodlanders, they require some protection whilst young, and shelter from strong winds, especially cold winds, is recommended to prevent leaf damage. Both in the wild and in cultivation they exhibit great diversity, with many different leaf shapes, sizes, colours, and textures, as well as a few with differing habits and sizes. This has led to numerous forms and cultivars arising from the earliest introductions, resulting in such variety that there ought to be one to suit every taste. However, the naming in quick succession of a raft of lookalike forms of F. polycarpa has caused significant confusion.

Pests and diseases are rarely a problem, although a new species of bark beetle, Xylechinus fatsiae, has been described in central Taiwan where it attacks fresh, moist trunks and branches (Ching-Shan 2020). Interestingly, Fatsia is sometimes a host for Orobanche hederae (Ivy Broomrape) in Europe (Frodin et al. 2003).

Propagation is by seed and cuttings, though seed is preferred except for named cultivars which should be propagated vegetatively. Fatsia polycarpa are only likely to set seed in the mildest climates; for example they set seed reliably at Tregrehan (Cornwall, UK) while 200 km further north at Crûg Farm in north west Wales they only set seed occasionally, sometimes not for years at a time (T. Hudson & B. Wynn-Jones, pers. comms. 2025). The production of both male-only and hermaphrodite flowers on the same plant is called andromonoecy: it is generally rare, though a feature of some araliads, including Fatsia, and has a bearing on reproduction in horticulture. To achieve seed set several individuals should be grown together: within andromonoecious Araliaceae, including Fatsia, the separation of male and female flowering phases is usually synchronised over the entire plant, leading to one or more cycles of flowering when only either all-male or bisexual flowers are open (synchronous dichogamy), thus minimising selfing and promoting cross-pollination (Plunkett et al. 2018). Seed separation can be achieved by placing fruit into a ziplock bag and squeezing the fruit to extract the seed, adding a little water if required; more water is then added, so that the fruit pulp floats to the top and the viable seed sinks, where it can be held in the corner of the bag whilst tipping out the flesh, the seed can be cleaned further if required and then dried on paper before sowing while fresh (T. Hudson & B. Wynn-Jones, pers. comms. 2025). Stem cuttings are possible but require a significant disfigurement of the plant to obtain enough propagation material; cuttings using the basal shoots arising from the bottom of the stem are also reportedly successful. For commercial purposes, tissue culture is often used to get the numbers required (T. Avent, pers. comm. 2025).

At a glance, Fatsia japonica and F. polycarpa can be differentiated by the latter’s leaves which are a light matt green rather than glossy dark green, and which have longer petioles, and may be larger than those of F. japonica. A significant difference concerns the ovaries: F. japonica is 5-carpellate and F. polycarpa 10-carpellate. The hybridization potential between F. japonica and F. polycarpa is occasionally mused over by enthusiasts, and it appears that it is a possibility: a combination of the elegant leaf shape of F. polycarpa with the handsome dark green gloss and greater hardiness of F. japonica would merit the experiment.

Dichotomous Key

1a. Leaves 7–9-lobed, glabrous, margins crenate to crenate-serrate, teeth rounded to blunt; ovary 5-carpellate ………….. 1. F. japonica

1b. Leaves 5–7-lobed, brown tomentose when young, margins serrate, teeth sharply pointed; ovary (8–)10(or 11)-carpellate …………………………………………………………………………………………………………………………………………………………………………2. F. polycarpa