Rhus

These trees and shrubs offer stunning autumn colour in the garden, writes Kevin Line

Image - Floramedia
Image - Floramedia

Rhus are deciduous or evergreen trees and shrubs that stand out as fine specimens in coastal areas, cottage gardens, flower beds and borders, and low-maintenance planting schemes. Rhus also works well planted with bold foliage plants as a planting companion. I have seen it surrounded by Tetrapanax papyrifer and Brugmansia to create an outstanding effect.

There are about 200 species of Rhus, which belong to the family Anacardiaceae, commonly known as the sumac family. They are a series of trouble-free plants, easily cultivated and thrive in fertile, well-drained soil. Rhus grows in south-, west- or east-facing aspects, which widens the gardener’s choice for siting.

The finest merit of the trees are the striking autumn-rich colours — red and orange, with a tint of yellow. Rhus are renowned for producing numerous suckers, but if these are removed, it can improve the display of bright autumn colour.

The trees are dioecious and monoecious and produce yellow to green flower clusters, but these are small and of little merit. Several species produce fruits on female plants that form a mass of dense crimson-fruiting heads.

The genus are widely distributed throughout the temperate region and also include some that grow in the tropics. The common species is Rhus typhina, known as Staghorn sumac because its young shoots are densely covered with velvety hairs.

Some people have an allergic reaction to parts of the tree which causes blistering.

R. typhina is native to eastern North America. It is a deciduous spreading tree that flowers in the summer. This particular species can grow up to 10m high, and spreads out suckers vigorously from the base.

The leaves are up to 60x20cm across, dark green above and pale blue beneath, turning orange/red in the autumn. Each leaf comprises 25 or more opposite-toothed lanceolate to oblong leaflets, 12x5cm across that taper to a point.

The species R. glabra is similar but has smooth, bloomy shoots and fruits. These have very short hairs that do not become matted together.

R. typhina is widely grown as an ornamental tree, which also includes R. typhina ‘Dissecta’ Award of Garden Merit (AGM), a form with deeply cut leaflets. ‘Dissecta’ will survive winters as low as minus-12°C and then regain new growth the following season. Another species,
R. lancea, is root hardy to minus-12°C, regaining new growth the following season.

R. chinensis, from east/south-east Asia, is a commonly grown species.
A spreading tree with an open, loose habit, it produces shiny large panicles of small white flowers in late summer. It is often misnamed
R. javanica, height up to 10m.

There are 17 species planted at Kew Gardens. The first to be planted was R. radicans in 1949. Others of the number include R. trichocarpa,
R. vernix and R. trilobata.

Some species can be pruned hard to the ground every other year in early spring to produce handsome foliage plants. The inner sections of the trees are woody and pithy . It is advisable to wear gloves because the sap is potentially harmful.

Propagation can be undertaken by division of suckers in late winter. Root cuttings are another method in the winter months which can prove successful. The process of seed propagation can be undertaken in winter or spring. Seeds need to be soaked for 48 hours and go through a chilling process for three months prior to sowing.

Rhus are generally pest free but are prone to coral spot and verticillium wilt.

What the specialists say

John Winterson, deputy buyer, RHS Plant Centres

"Wisley Plant Centre sells a range of seven different Rhus, but availability is sporadic. In fact, last year we only managed to stock two of them — R.× pulvinata ‘Red Autumn Lace’ (AGM) and R. typhina dissecta ‘Tiger Eyes’. Both are shorter cultivars than the straight species and tend to be showy on arrival at the centre. ‘Tiger Eyes’ was new in 2004 and has fabulous bright golden foliage. Both are ideal for those areas with difficult soil and are great to brighten up dull corners, especially with their autumn foliage.

"Generally Rhus are sold as small 3-litre plants. Often they are irregular in habit, so are best given some space to display rather than squashing them in on planteria beds. Shelf life is good but if you only want to get them in for autumn colour then the window is short, because they can drop leaves quickly depending on the weather."

Bleddyn & Sue Wynn Jones, owners, Crûg Farm Plants, Caernarfon.

"Depending on which side of the pond you originate from, R. ambigua may easily be confused with poison ivy or Toxicodendron radicans (syn R. toxicodendron), a well known toxic creeper from North America, which causes blistering on merely a gentle brushing. Small wonder that our American visitors throw a wobbler when we introduce them to our aerial rooting climber as a Rhus.
They take a fair bit of convincing that in 20 or so years that we have been growing and handling this colourful climber, there have been no problems.

"It did not take long for this species to become a firm favourite with our customers, leaving us struggling to keep up with the demand. This is despite the lack of any ornament that could be attributed to the rather dull small flowers or the resulting small seed capsules.

"Like all the aerial rooting climbers that we cultivate — including climbing hydrangeas, Parthenocissus, Schizophragma and ivies— we plant them a little way from the host wall or tree trunk that they are to climb. We even bury the flexuous stems so that just the growing tips emerge from the ground, spreading them over a metre or so parallel with its host. This forces the plant to creep along the soil surface, rooting as it does so, which, in turn, boosts its growth rate and ability to climb.

Steve Dance, Burncoose Nurseries, Gwennap, Redruth, Cornwall.

"I prefer R. glabra and its variety of ‘Laciniata’. Both of these have lovely autumn colour. They also
have the advantage of not being as invasive as R. typhina. They love to be in a sunny position with a well-drained soil."

Species & varieties

Rhus ×pulvinata ( R. glabra ×R. typhina) (R × hybrida rehder) is a medium-sized shrub with downy stems, intermediate between the parents. The leaves turn to rich scarlet, orange and flame in the autumn. It occurs with parents in the wild. ‘Red Autumn Lace’ AGM (H5) is a fine-foliage plant. Its large fern-like leaves with deeply cut leaflets turn orange, yellow and red in autumn. Fruiting clusters red, shoots green or red, flushed not bloomy with sparse hairs. It is commonly grown as R. Glabra ‘Laciniata’. Originally recognised in the Sir Harold Hillier Gardens and Arboretum.

R. trichocarpa is a splendid large shrub to small tree, comprising large pinnate downy leaves. These are copper-pink when juvenile, turning to deep orange in the autumn. Yellow bristly fruits are borne in deep drooping clusters on female plants in autumn.

R. typhina ‘Dissecta’ AGM (H6) is a striking female form of Typhina, comprising deeply incised leaflets, creating a fern-like effect, orange and yellow autumn colours. Often grown as ‘Laciniata’.

R. chinensis (R. javanica) is a small dioecious broad-headed tree or large irregular shrub, attaining about 6m in the British Isles. The pinnate coarsely-toothed leaves colour richly in the autumn, and have a winged rachis. The flowers are yellowish-white and produced in large, terminal panicles in late summer.

R. glabra, also known as Sooth sumac, is a wide-spreading, medium-sized shrub with glabrous, glaucous stems with attractive glabrous pinnate leaves. These are glaucous beneath and turn an intense red, orange or yellow in the autumn. The erect scarlet hairy plume-like fruit clusters of the female plant are conspicuous in autumn. R. glabra ‘Laciniata’ is a form with deeply cut leaflets.

R. typhina is a wide-spreading sparsely branched small tree or an irregular large shrub that develops a flat-topped appearance, noticeable in winter. The thick pithy branches are covered when young with a thick coat of reddish brown hairs. Large pinnate leaves turn a rich orange, yellow, red or purple in the autumn.

Large erect green clusters of male flowers and smaller female clusters are borne on separate plants. The dense conical clusters of crimson hairy fruits are decorative in the later stages of the season. Sometimes these form small thickets of suckering stems.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

Sargent's solutions - how to attract the best staff for your business

Sargent's solutions - how to attract the best staff for your business

There are ways to find quality candidates for horticultural jobs if you widen your search parameters, Alan Sargent suggests.

Business Planning - Staff are your greatest asset

Business Planning - Staff are your greatest asset

An effective strategy to retain staff is the best way for any business to avoid a potential recruitment crisis, Neville Stein advises.

IoG Saltex 2017 - Kit showcase

IoG Saltex 2017 - Kit showcase

Mowers, turf care, battery equipment, seeds, arboriculture kit and weed control will all see a wide range of new releases at Saltex, Sally Drury reports.


Horticulture Jobs
More Horticulture Jobs

IOG Saltex

Get set for IoG Saltex 2017 with our comprehensive show guide and exhibitor info.

Are you a landscape supplier?

Horticulture Week Landscape Project Leads

If so, you should be receiving our new service for Horticulture Week subscribers delivering landscape project leads from live, approved, planning applications across the UK.

Industry Data

An exclusive report for HW subscribers revealing the key development trends, clients and locations for 2017.

Products & Kit Resources

BALI National Landscape Awards 2016

Read all about the winning projects in the awards, run in association with Horticulture Week.

Noel Farrer

Founding partner of Farrer Huxley Associates Noel Farrer on landscape and green space
 

Read Noel Farrer