RHS the Plantsman, June 2015

Metapanax davidii in southern England forms a broad, free-flowering shrub Metapanax andDendropanax in cultivation The Araliaceae contains a broad range of evergreen shrubs suitable for adventurous gardeners. Eric Hsu considers two close relatives. he popularity of hardy and Metapanax to arborescent, adult Dendropanax Schefflera in gardens has stages of Hedera helix (ivy) hints at Dendropanax is largely a subtropical Tpaved the way for lesser their placement within the Araliaceae. to tropical genus, native to Central known genera of the Araliaceae. Their foliage fits well with the sub and South America and East and Oreopanax have recently been profiled tropical look favoured in temperate Southeast Asia. The 70–90 species in these pages (Smith 2014) and gardens, as well as in woodland are evergreen shrubs and trees that Pseudopanax elsewhere (Smith 2011), settings, which approximate to their have alternate leaves which are either but a few species of Dendropanax and native haunts in east Asia. However, simple or 3–5lobed. The bisexual Metapanax are increasingly becoming these shrubs are not for those seek flowers are arranged in umbels and available. The last two are the subject ing bold flowers, since they are green the fruits are globose, fleshy and of this article. and nondescript, despite having black – remarkably similar to those The resemblance of Dendropanax interesting spiral arrangements. of Hedera helix. ➤ June 2015 121 Genus profile Andrea Jones Andrea the distinctive foliage of Dendropanax trifidus Curiously, botanist Charles Sprague Sargent (1894) had little to say about Dendropanax, remarking dryly: ‘…Dendropanax, a tropical genus of trees and shrubs of the New World, as well as of the Old, reaches southern Japan with a single shrubby species, Dendropanax Japonicum [now D. trifidus].’ The species most often grown in temperate gardens is Dendropanax trifidus, native to the Japanese islands of Honshu, Kyushu and Shikoku. Ohwi (1965) lists synonyms of this species in a wide range of Araliaceae genera, such as Aralia, Gilibertia, Hedera and Textoria, and it even has a synonym in Acer – not even remotely related to Araliaceae. This species has confused many botanists, perhaps because of its dimorphic foliage (the juvenile leaves are lobed and the adult ones are entire) and the absence of fruits in herbarium specimens. Dendropanax trifidusgrowing under glass in the uk Dendropanax trifidus is probably Shilton Clive the hardiest species in the genus and capable of withstanding some cold kEy to DEnDropanax anD MEtapanax in cultivation in thE uk & uS temperatures, but not heavy frost. Leaves 2–3 lobed, petioles to 20cm Dendropanax trifidus Dendropanax cf. kwangsiensis is listed Leaves simple, sometimes 2–3lobed or divided into 3 leaflets; in the RHS Plant Finder 2014, but leaflets typically more than 3cm wide; petioles to 20cm M. davidii its longterm prospects in cultivation Leaves with 2–5 leaflets; leaflets 1–3 cm wide; petioles to 12cm M. delavayi are unknown. 122 June 2015 PlantsmanThe Molecular work has since demonstrated that the two species warrant their own generic status, in Metapanax, which is closely allied to Eleutherococcus and Macropanax (Mitchell & Wagstaff 1997, Wen et al. 2001, Wen & Frodin 2001). Nothopanax is no longer recognized, its species having been moved to Neopanax, a close ally of Pseudopanax, the inflorescence ofMetapanax davidii marks it out as a Doug Smith and Metapanax (Frodin & Govaerts member of the araliaceae 2004). In horticulture, Metapanax species are still sometimes found listed as Pseudopanax. Metapanax davidii This species is found in moist forests, roadsides and rocky slopes in the Chinese provinces of Guizhou, Hubei, Huna, Shaanxi, Sichuan and Yunnan (Hoo & Tseng 1978) and north Vietnam at 800–3,000m. It resembles a subtropical, arborescent ivy and differs from M. delavayi on account of its usually simple, although sometimes palmately divided or compound, leaves with the variable foliage of Metapanax davidii, but Doug Smith leaflets more than 2.5cm wide. The note the lack of leaflet stalks leaflets lack the petiolules (leaflet stalks) evident in M. delavayi. Metapanax fluctuated. Franchet (1886, 1896) Although Metapanax was recognized originally placed the species in Metapanax delavayi as a member of the Araliaceae in Panax, then Harms (1900) moved This species is restricted to the 1992 (Frodin 1992), it was not them to Nothopanax. Due to leaf forests of Guizhou and Yunnan formally described until 2001 (Wen differences (simple or palmately (Hoo & Tseng 1978). The leaves & Frodin 2001). There are just two compound in Metapanax versus generally have three leaflets, each species in the genus, M. davidii and pinnately compound in Nothopanax), with a short petiolule. The leaflet M. delavayi (Hoo & Tseng 1978, Hô the species were sometimes structure gives this species a more 1993, Wen & Frodin 2001). Both considered distinct from southeast delicate appearance, much closer are evergreen shrubs to trees, semi Asian Nothopanax (Miquel 1857, to Schefflera than the Hederalike deciduous in colder climates, with Philipson 1951). Philipson (1951) M. davidii. alternate, hairless leaves that are then reduced Nothopanax to Two cultivars are offered in either simple or compound. The synonymy in Polyscias, moving our horticulture. One was collected by rather inconspicuous 5merous two species into Pseudopanax plantsman Dan Hinkley from the flowers are arranged in umbels (Philipson 1965). However, the Yulong mountains in Yunnan and is around a central panicle and the general consensus had been their marketed by Monrovia nursery of fruits are flat, black berries. In both recognition in Nothopanax (Li 1941, California as M. delavayi Jade Dragon species the petioles of immature Hoo & Tseng 1978, Shang 1985). (‘MonYuLong’). Its performance in leaves are long, to 15cm, but shorter Only Hoo (1961) questioned their eastern US has yet to be determined. on mature leaves. placement in Nothopanax, but Cistus Nursery of Oregon offers Their taxonomic position has refrained from moving them. M. delavayi ‘Stout’, a selection ➤ June 2015 123 Genus profile Doug Smith the leaflets ofMetapanax delavayi (and above and right) are typically narrower and more numerous than those of M. davidii. Short leaflet stalks are also evident on some leaves. temperatures of 15°c with minor foliar damage (Hogan 2008). Although new leaves of Metapanax can be easily damaged at 1°c, Hogan (2008) reported M. davidii hardy to slightly below 18°c if sheltered from cold winds, or 14°c without, and M. delavayi to 18°c without protect ion. In the Pacific Northwest, plants of both species survived the December 2008 and 2009 freezes. They appear unfussy about soil type, but seem to be happiest in neutral loam. They resent poorly Doug Smith drained conditions but a lack of moisture can result in stunted growth or yellowing foliage. from seed, which differs from the warmer gardens of south and west No serious pests or diseases species in its leaflets of a thicker Britain and Ireland. However, given trouble the plants, although scale texture. their evergreen nature, Dendropanax insect may bother stressed plants. and Metapanax require careful siting, Plants are normally propagated Cultivation such as against a wall, if grown in vegetatively. Cuttings taken at any Dendropanax and Metapanax are both colder climates. Where there are time of the year will usually root suitable for gardens in the southeast heavy frosts they should be fairly easily, providing a small US where hot and humid summers overwintered at a minimum of 4°c in amount of old wood is left on the approximate their climates in East a greenhouse or conservatory. base. Bottom heat will speed up the Asia. They can also be grown in the Dendropanax trifidus has survived process. 124 June 2015 PlantsmanThe Notable specimens perform best in the southeast. At the 2002 in open ground, with some Established specimens of Sarah P. Duke Gardens in North shade, is now about 2m high and Dendropanax trifidus can be admired Carolina there are specimens of more than 4m wide. It forms a at the J.C. Raulston Arboretum in M. delavayi raised from seed highly ornamental, domeshaped, North Carolina and the Elisabeth collected at Jishijiulongtan, evergreen shrub that is kept under Carey Miller Botanic Garden in Kunming, China, in 1994. At control by pruning lightly in spring. Washington state. Young plants Chanticleer garden in Pennsylvania, The new leaves appear relatively of D. trifidus survived the first few a specimen of M. delavayi planted in early in the spring and are often winters, but unfortunately died in autumn near a westfacing house wall caught be late frosts. However, this the winter of 2013–14, in a favoured did not survive the winter. However, induces further shoots to break area close to glasshouses at the Scott it may have fared better if planted in below the lost terminal bud which Arboretum of Swarthmore College spring. Metapanax can also be seen at can actually improve the shape, but in Pennsylvania. In the UK the San Francisco Botanical Garden will compromise flowering. D. trifidus is rarely grown and and the Royal Botanic Garden In the UK M. delavayi leafs out seems intolerant of frost. Melbourne, Victoria, Australia. later. While some scorching and At the University of Washington In the south of the UK there are damage of terminal buds is likely Botanic Gardens in Washington several wellestablished specimens of to occur in hard winters, cold state there is a sizable specimen of Metapanax. A plant of M. davidii in accentuates the red colouration M. davidii approximately 4m tall. the National Plant Collection of often seen on the leaf undersides. On the east coast of the US, plants Araliaceae in Hampshire, planted in Its hardiness has not been fully refereNCes tested in the UK, but a specimen in Doug Smith Decaisne, J & Planchon, J (1854) parsimony analysis of rDNA sequence the National Plant Collection has Araliaceae: Dendropanax.

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