Idesia polycarpa Maxim.

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Credits

Owen Johnson (2022)

Recommended citation
Johnson, O. (2022), 'Idesia polycarpa' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/idesia/idesia-polycarpa/). Accessed 2022-06-29.

Genus

Common Names

  • Iigiri
  • Chinese Wonder Tree

Synonyms

  • Polycarpa maximowiczii Linden ex Carrière
  • Cathayeia polycarpa (Maxim.) Ohwi
  • Idesia fujianensis G.S. Fan
  • Flacourtia japonica Lavallée

Infraspecifics

Other taxa in genus

    Glossary

    dbh
    Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
    androdioecious
    With only male or only hermaphrodite flowers on individual plants.
    pollination
    Act of placing pollen on the stigma. Various agents may initiate pollination including animals and the wind.
    pubescent
    Covered in hairs.

    Credits

    Owen Johnson (2022)

    Recommended citation
    Johnson, O. (2022), 'Idesia polycarpa' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/idesia/idesia-polycarpa/). Accessed 2022-06-29.

    A fast-growing tree to 20 m tall; habit open; branches level, foliage often in tiers. Bark greyish, with darker lenticels; twigs glabrous or sparsely pubescent, thick, with a pithy core. Buds red-brown, c. 6 mm long, rounded. Leaves broad-ovate to cordate, (6–)8–16(–20) cm × (4–)7–15(–20) cm, bright green above, glaucous beneath; glabrous above except for dense patch of hairs at the base; underneath, sparsely hairy under the veins to densely pubescent; base often deeply cordate, tip acuminate; main veins in c. 6 pairs, with usually 5 veins from the base; margin with rather remote gland-tipped teeth; petiole long, (4–)5–15 cm, reddish, usually glabrous. Flower-heads (13–)20–30 cm long; flowers with pubescent stalks; sepals elliptic to slightly obovate, yellow-green, densely pubescent; each flower 9–16 mm wide (male flowers slightly larger and more scented). Berry ripening from yellow-green to brown then red, ultimately drying blackish, globose, 8–10 mm wide. Seed broadly ovoid, 2–3 mm. Flowers (in the wild) April–May, fruit ripens October–November. (Flora of China 2022; Bean 1981).

    Distribution  China Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang JapanNorth KoreaSouth KoreaRussia Near the Chinese and Korean borders Taiwan

    Habitat Forests, to an altitude of 3000 m in southern China.

    USDA Hardiness Zone 6

    RHS Hardiness Rating H6

    Conservation status Not evaluated (NE)

    Idesia polycarpa was first collected by the Russian botanist Karl Maximovich in Japan in 1860–1, five years before his description of this tree was published (Clarke 1988); seed was also sent from Japan two years later by Richard Oldham, collecting for the Royal Botanic Gardens, Kew (Bean 1981). The tree is sufficently ornamental and easy to grow to have retained a continuous place in western gardens since this time and – without ever really becoming well known – it is now represented by many different wild collections from China, Taiwan, Japan and South Korea.

    The large but by no means coarse heart-shaped leaves may suggest one fairly close relative, the balsam poplar Populus szechuanica, while the vigorous but rather flimsy straight-stemmed growth can also recall the – unrelated – bean trees (Catalpa). The scented flowers are interesting rather than spectacular, but the berries are unique: they are often compared to bunches of grapes but are carried more distantly in swags hanging under the leaves. These leaves tend to drop late and without much colour, but after a warm, dry autumn – and if there are not too many fruit-eating birds – the berries will hang on into winter, a royal red colour. The species seems to be strictly dioecious, and so to produce this show a female tree is needed, with a male close enough to allow insect pollination; female trees on their own can also produce a sparing crop of fruit apomictically (Wang et al. 2017). Gardeners with enough room consequently tend to plant this species in seedling groups and to retain at least one male and one female once they are old enough to flower. In such cases the male tree is typically more vigorous and luxuriant (Tree Register 2022); this is always likely to be the case among dioecious trees, since the males do not have to divert energy into fruit production, but is seldom so easy to observe.

    In addition to the type of the species, Flora of China 2022 recognises two varieties: var. fujianensis (G.S. Fan) S.S. Lai was originally described in 1995 as a new species (I. fujianensis G.S. Fan) and is confined to the subtropical south of China; it has smaller leaves which are downy beneath. Var. vestita Diels, widespread in China and Japan at least, also has leaves which are softly pubescent underneath; plants of this kind were introduced from western China by Ernest Wilson in 1908 (Bean 1981; Edwards & Marshall 2019) and again, from Sichuan, in the 1990s (SICH 1615). Meanwhile, Plants of the World Online (2022) places var. fujianensis in synonymy with the type and does not recognise var. vestita; it certainly seems the case that the foliage of wild populations can run across a range from densely downy to almost hairless, while some trees of northern origin can also have leaves much smaller than has become the norm within western gardens – where there may have been some half-conscious selection for imposing foliage. One quite small-leaved recent introduction is KE 3770, collected in western South Korea in 1985; this has made relatively compact and dainty trees in the Valley Gardens at Windsor Great Park, Berkshire, which, in terms of foliage and habit, are likely to be mistaken for their near ally Poliothyrsis sinensis.

    In southern England, Idesia polycarpa has reached 20 m in woodland shelter at Stourhead in Wiltshire and 60 cm dbh in a small garden near Linton, Kent (Tree Register 2022); these both grow in the kind of deep, slightly acidic, sandy loam which suits most trees best. The species will survive above chalk, given enough topsoil (Edwards & Marshall 2019). Although plenty of summer and autumn heat is needed for a good display of fruit, the tree itself can sometimes thrive in cooler, wetter conditions; a good group at the Linn Botanic Garden in coastal Argyll was grown from seed collected in China by Jamie Taggart, a young botanist who fell to his death while plant-hunting in Vietnam in 2013. Idesia is easy to raise from seed in areas like the south-eastern United States where summers are long enough for these to ripen fully (Dirr 2009); the seedlings are easy to transplant bare-rooted, and the tree suffers from very few pests or diseases; it even survives in Ottawa, Canada (American Climate Zone 4b) (Stewart 2022), though in these conditions it is cut to the ground each winter. Plants of Korean and Russian provenance might prove even hardier, and two Korean accessions are grown in the Linnaean Garden at Uppsala, Sweden (Royal Botanic Garden Edinburgh 2022).

    For a tree which has never become common as an ornamental, the cultivated distribution of Idesia is certainly wide. It is represented in botanic gardens as far apart as New York and Budapest (Royal Botanic Garden Edinburgh 2022), and – like so many temperate trees – it seems from online images to flourish and fruit particularly well in New Zealand (New Zealand Tree Trust 2022). As of 2022, it was available from nurseries in Australia, Italy, the Netherlands and France (in the form of seedlings from KR 4700, offered by Pépinières Aoba). In the UK there are several suppliers (Royal Horticultural Society 2020), including Crûg Farm which offers scions of CWJ 13837, collected in Japan.

    For all these merits, Idesia is a short lived plant at best – often showing signs of decline after just a few decades – and it would be misleading to recommend it unreservedly as a garden tree. For every good specimen on the Tree Register of Britain and Ireland, there are two or three which are sickly, mis-shapen or just sad-looking. Very few have passed the tougher test of establishment within public parks, though there are youngsters at the Canterbury City Cemetery and the Coate Water Tree Collection in Swindon, two public arboreta which are exemplary in their range and ambition.


    var. vestita Diels

    Differs from the type chiefly by the undersurface of the leaves being densely downy. Wilson found it in Western Szechwan, China at elevations of over 8,000 ft as a tree 20 to 50 ft high with a trunk 1 ft in diameter and introduced it in 1908. The flowers are yellow as in the type; fruit described as brick red. The species varies considerably in the size and shape of its leaves, but this variety is well distinguished by its downy leaves which are almost felted when young. Forrest sent home seeds of it and of the typical variety as well. The late Sir Frederick Stern raised the var. vestita from Farrer’s seeds sent from Kansu, but only one was planted and this was male (The Chalk Garden, pp. 147-8). Farrer described it as ‘a beautiful and graceful tree, with abundant long and loose panicles of rich scarlet berries’.