RHSPLANTTRIALSBULLETIN

Number 21 21 May May 2008 2008

Clematis alpina & C. macropetala Wendy Wesley Trials Officer, RHS Garden Wisley RHS Trial of alpina and C. macropetala

Clematis alpina and C. macropetala are relatively small- Any pruning should be carried out immediately after flowered Clematis species belonging to the subgenus flowering has finished so that new growth can take place to Atragene. Historically the single-flowered were provide for the following season. A light annual assigned to C. alpina and doubles to C. macropetala, but trim is most effective as they do not always respond well to now many are known, or suspected, to be hybrids between being cut back into wood which is more than a few years the two or with other species in the subgenus such as old. It is beneficial to cut the whole hard back for the C. fauriei, C. ochotensis, and C. sibirica. These hybrids are first couple of years in order to build up a well-branched listed without a specific epithet, but are included together structure from the base. Clematis are best planted deeply with their parents in the Atragene Group. and the base of the plant protected to reduce moisture loss. The root system of both species are known to be particularly The nodding, bell-shaped flowers of these deciduous, woody fragile. climbers are mainly produced in spring on the previous year’s growth, sometimes providing a second flush in The trial was initially grown at a site in Wisley Village, summer on the new shoots. planted in 1997. did not establish well and many suffered from late frost damage The trial was propagated in 1999 and planted in April 2001 at Howard’s Field in Wisley Cultivation Garden. Even on this site there were deaths. These hardy plants are suitable for growing on fences, walls and pergolas, in borders on tripods and wigwams and can Objectives also be allowed to scramble through large shrubs or small The objectives of the trial were to: trees. Most can also be grown successfully in containers. ⅷ compare and assess old and new cultivars They will grow well in a wide range of soils. The trial at Wisley demonstrated sites subject to late spring frosts and ⅷ recommend the Award of Garden Merit to those exposed to early morning sun should be avoided. The acid, considered to be the best sandy soil of the trial site also proved to be unsuitable and ⅷ check nomenclature better establishment might have been achieved by the ⅷ obtain specimens, photographs and descriptions as a incorporation of plenty of humus, to increase its water record to be held in the RHS Herbarium at Wisley. retention, and lime to raise the pH.

Clematis alpina Clematis macropetala

sepal

vertical section stamen through

vertical section staminode through flower

outer petal-like spoon-shaped staminode staminode inner linear staminode

sepal © Niki Simpson 2008

C. alpina C. macropetala the flower has four petal-like sepals; the the flower has four petal-like sepals; the outer Front cover: outermost stamens are modified to form spoon staminodes are transformed into narrow petal-like Clematis macropetala shaped staminodes which are normally creamy- staminodes (usually 4 to 12 in number) which ‘Lagoon’ (Photo white . resemble the sepals in length and colour, giving Wendy Wesley) the appearance of double or semi-double flowers. The inner staminodes are narrow, blue-white and Far right: Clematis ‘Frankie’ (Photo linear. Wendy Wesley)

2 RHS Plant Trials Bulletin ‘They breathe a wonderful freshness, with their flowers on tip-toe for flight, spangled against newly expanded foliage of palest green.’ Christopher Lloyd in his 1965 book Clematis.

Award of Garden Merit (AGM)

Clematis alpina AGM(H4)1993* Clematis alpina ‘Pamela Jackman’ AGM(H4)2005 Clematis ‘Ballet Skirt’ AGM(H4)2005 Clematis ‘Constance’ AGM(H4)2002 Clematis ‘Foxy’ AGM(H4)2002 Clematis ‘Frances Rivis’ AGM(H4)1993 Clematis ‘Frankie’ AGM(H4)2002 Clematis ‘Helsingborg’ AGM(H4)1993 Clematis ‘Jacqueline du Pré’ AGM(H4)2002 Clematis macropetala ‘Lagoon’ AGM(H4)2002 Clematis macropetala AGM(H4)1993* ‘Markham’s Pink’ Clematis macropetala ‘Wesselton’ AGM(H4)2005 Clematis ‘Pauline’ AGM(H4)2005 Clematis ‘Pink Flamingo’ AGM(H4)2002 Clematis ‘Rosy O’Grady’ AGM(H4)2002 Clematis ‘White Columbine’ AGM(H4)1993

* Recommended to be rescinded at the AGM Review in 2012

Hardiness rating H4 = hardy throughout the British Isles

Judging Criteria The Woody Plant Trials Subcommittee assessed entries in the trial for the Award of Garden Merit using the following criteria: ⅷ size, quantity and quality of flower and seed heads ⅷ foliage ⅷ length of flowering period ⅷ growing habit ⅷ vigour

The AGM is only awarded to plants that are: ⅷ excellent for garden decoration ⅷ available from nurseries ⅷ reasonably resistant to pests and diseases ⅷ of good constitution ⅷ essentially stable in form and colour ⅷ reasonably easy to grow

Clematis alpina & C. macropetala 3 Award of Garden Merit descriptions

Clematis alpina ‘Pamela Description: Deep pink, Jackman’ semi-double, nodding, AGM(H4)2005 lightly scented flowers; Sent by Guernsey Clematis 4 sepals 3.5 ϫ 1.5cm, Nursery Ltd. purple-violet (81B). Outer staminodes lanceolate, Description: Nodding, bell- same length and colour. shaped flowers with 4 flat, Opposite and biternate pointed sepals, slightly leaves, serrated margin, recurved, 4.5 ϫ 1.8cm, yellow-green (144A), matt, inside violet blue (96A), glabrous upper surface. outside a little paler. Many Flowering throughout central staminodes, outer April. spathulate, blunt, white flushed purple, green Comments: Best semi- tipped; inner linear, double pink, well covered pointed. Ternate, toothed, with flowers from top to yellow-green (144A). bottom. Nodding ovoid bud with grey, felt-like hairs. Flowering throughout Clematis ‘Foxy’ April. Syn. C. alpina ‘Foxy’. Comments: A good contrast AGM(H4)2002 between lime green foliage Sent by Guernsey Clematis and intense violet blue Nursery Ltd. . flower. Flowers consistently Description: Bell-shaped well. Distinct. flower 5.3cm wide and 3.5cm long. Four pale pink, (78B to 78C), Clematis ‘Ballet Skirt’ lanceolate sepals with Syn. C. macropetala ‘Ballet darker shading on outside Skirt’. surface, paler margins, to Chris Sanders AGM(H4)2005 5cm. Pale pink Sent by Robin Savill staminodes; nodding Clematis and Goscote ovoid bud. Yellow-green Nurseries Ltd. leaves (147B). Flowering late March to early May. Description: Semi-double, bell-shaped, nodding Comments: relatively large flowers, 4 lanceolate, flower, pretty pink and white pointed sepals, red-purple bicolour. Nice paler pink edge (70A) paling to (77C), to sepal. Distinct 5 ϫ 2cm. Many outer staminodes same length and colour as sepals, Clematis ‘Frances Rivis’ 5 ϫ 0.9cm. Yellow-green Syns. C. alpina ‘Frances leaves, opposite and Rivis’; C. alpina ‘Mrs Rivis’; biternate. Flowering late ‘Mrs Rivis; C. alpina March to end April. thibetica hort.; C. alpina ‘Blue Giant’; ‘Blue Giant’; Comments: Larger flowers C. ochotensis ‘Frances Rivis’. than ‘Markham’s Pink’ and more free flowering. AGM(H4)1993 Sent by J van Zoest. Description: Single, Clematis ‘Constance’ nodding, broadly bell- Syn. C. alpina ‘Constance’. shaped flowers. Sepals AGM(H4)2002 violet-blue (96A to 97B) 4.6 Sent by Guernsey Clematis ϫ 2cm, white staminodes. Nursery Ltd. Yellow-green leaves (144A). Some plants with longer narrower sepals sold as

4 RHS Plant Trials Bulletin All descriptions are based on plants grown in the RHS Trial of Clematis alpina and C. macropetala. Plants grown elsewhere may differ slightly according to cultivation conditions. Colour codes were taken using the RHS Colour Chart. The fifth edition (2007) is available from RHSE Mail Order, Wisley, Surrey GU23 6QB.

C. ‘Frances Rivis’ in the UK, Comments: Flowers good are probably C. ‘Blue dark colour. Attractive Dancer’. Flowering chocolate red stems and throughout April. petioles. Makes a striking display, flowers appearing to Comments: Distinctive deep drip down the plant. blue, broad sepals, and fresh lime green foliage. Floriferous. Clematis ‘Jacqueline du Pré’ Syn. C. alpina ‘Jacqueline Clematis ‘Frankie’ du Pré’. Syns. C. alpina ‘Frankie’ and C. ochotensis ‘Frankie’. AGM(H4)2002 AGM(H4)2002 Sent by Goscote Nurseries and Bridgemere Nurseries. Sent by Guernsey Clematis Nursery. Description: Semi-nodding flowers with 4 soft pink Description: Bell-shaped, sepals, rosy mauve-purple semi-double nodding (81C to 80B), margin silver flowers, pale violet-blue Chris Sanders pink, 5–6 ϫ 2.5cm. Pale (97A) with a bronze tint, pink, spathulate fading with age, very staminodes. Flowering slightly fragrant. Sepals from late April to May. lanceolate to broadly elliptical, margin recurved, Comments: A vigorous, to 5cm long. Petal-like with large, rosy pink staminodes creamy white, flowers, the outer sepals of tinged and tipped with which are strikingly blue. Buds globose to ovoid. margined silvery white. Leaves slightly darker than yellow-green (144A). Flowering throughout Clematis macropetala April. ‘Lagoon’ Syn. C. macropetala ‘Blue Comments: Pretty violet- Lagoon’. blue flowers with inner white sepals tipped blue. Displays AGM(H4)2002 flower well, good vigour. Sent by Sheila Chapman, Guernsey Clematis, Sussex Clematis Nursery and Clematis ‘Helsingborg’ Treasures of Tenbury. Syn. C. alpina Description: Semi-double, ‘Helsingborg’. bell-shaped flowers to AGM(H4)1993 7.3cm wide, 3.5cm long. Sent by Guernsey Clematis Sepals, outside violet-blue Nursery Ltd. (93B), inside violet-blue (96B). Twelve sepal-like Description: Broadly bell- staminodes, same length shaped, nodding, single and colour as sepals, pale flowers, 5.6cm wide, margin. c.50 inner 4.2cm long, sepals violet staminodes, white with (86A), paler margin, pale green tips, occasional recurved towards tip. blue splash. Ovoid, bud, Staminodes spathulate, pointed and hairy. Leaves same colour as sepals. yellow-green (144A), Long, ovoid & pointed glossy reverse. Flowering buds. Fresh yellow-green mid April to mid May (144A) leaves, glabrous, matt and fairly deeply Comments: Vigorous, strong veined. Flowering late colour, good foliage, April to end May.

Clematis alpina & C. macropetala 5 Award of Garden Merit descriptions

Clematis macropetala long, paler pink ‘Wesselton’ staminodes. Yellow-green AGM(H4)2005 leaves, (144A). Flowering Sent by Thorncroft Clematis. throughout May. Description: Vigorous with Comments: Nodding flowers striking, distinctive, which are a lovely pale pink double, pendent flowers to with darker pink veins 4.8cm. Four narrow, outer Usually repeat flowers in sepals violet-blue (94B); 14 August. outer staminodes slightly longer than the sepals, (94B) with white Clematis ‘Rosy O’Grady’ undertone particularly at Syns. C. macropetala ‘Rosy base, 40 inner staminodes, O’Grady’, C. macropetala half sepal length. Bronze- ‘Rosie O’Grady’, purple bud with pale hairs C. macropetala ‘Rosy on lower half. Mid green Oguredeii’ and leaves, (146A). Flowering C. macropetala ‘Rosy late March to late April. O’Gready’. Comments: Superb. The AGM(H4)2002 bluest, largest flowered Not in trial C. macropetala, excellent Description: Semi-double, Chris Sanders leaf, a first class plant. Early. nodding, mauve-pink flowers, 10–12cm wide. Four lanceolate to oblong Clematis ‘Pauline’ ovate, pointed, recurved Syns. C. alpina ‘Pauline’, sepals, 5–7cm in length, C. alpina ‘Paulina’, outside darker than inside C. ochotensis ‘Pauline’, and veined. Outer C. macropetala ‘Pauline’. staminodes 4 long, pale mauve pink (75C), 4 short, AGM(H4)2005 creamy white inner Sent by Guernsey Clematis staminodes. Flowering mid Nursery Ltd. April to mid May. Description: Semi-double, Comments: A vigorous and bell-shaped, nodding distinctive cultivar with flowers. Four sepals dark to spiky, lantern-like flowers. bright blue, flushed with violet, 4–7cm long. Outer staminodes blue and Clematis ‘White white, inner staminodes Columbine’ white tipped green. Syns. C. alpina ‘Columbine Flowering mid April to White’, C. alpina ‘White mid May. Columbine’. C. ‘Columbine’ Comments: Useful late 3 unknown flowerer. Attractive dark blue AGM(H4)1993 bud becoming a rich blue violet flower. Sent by Sheila Chapman Clematis. Description: Single flower, Clematis ‘Pink Flamingo’ four pure white sepals, AGM (H4)2002 3.8cm wide ϫ 4cm long, lightly fragrant; drooping, Sent by Guernsey Clematis puckered bud. Pale green Nursery Ltd. leaves (146B). Flowering Description: Semi-double, early April to early May. nodding flowers, 3–5cm wide. Sepals red-purple Comments: Lovely white (72A), with darker veining flower. and flush at base, 4–5 cm

6 RHS Plant Trials Bulletin Selection guide by colour = AGM = Award of Garden Merit

Clematis ‘White Clematis ‘Rosy Pagoda’ Columbine’ A very attractive flower but Long narrow sepals, possibly plant lacked impact in the the best white; all white- trial. flowered cultivars have delicate pale green foliage. ‘Ruby’ ϫ unknown, raised by M Johnson in 1974 from seed Introduced by Treasures of sent by Hans R. Horn-Gfeller Tenbury in 1986, ‘Columbine’ in Switzerland. ϫ unknown April to early May Early April to early May

Clematis ‘Burford White’ Clematis ‘Ballet Skirt’

Masses of light green buds, Larger flower than good lime green foliage, short ‘Markham’s Pink’. white sepals, good vigour. Consistently freer-flowering.

Chance seedling found in N. Raised and introduced in Wales by a customer of 1981 by Stanley J Zubrowski, Treasures of Tenbury who Saskatchewan, Canada, introduced it c.1985. introduced by R J Evison. ‘Rosy O’Grady’ ϫ unknown. Throughout April Late March to late April

Clematis ‘Snowbird’ Clematis macropetala ‘Markham’s Pink’ A beautiful double flower, but lacked vigour in the trial. Deeper pink than ‘Ballet Skirt’ and smaller flowered. Raised by B Fretwell in 1969, ‘Markham’s Pink’ ϫ unknown. Raised by E Markham, a previous Head Gardener at Late April to mid May Gravetye Manor. Introduced in 1935.

Throughout April

Clematis ‘Willy’ Clematis ‘Foxy’

Very pale pink, floriferous but Distinct, pretty pink bi- in trial had less impact than coloured flower, attractive ‘Jacqueline du Pré’. light edge to darker pink sepals, may produce a second Raised and introduced in 1971 late flush. by Pieter G Zwijnenburg, Boskoop, Netherlands, C. A sport from ‘Frankie’, raised alpina ϫ unknown by R J Evison, introduced 1996. Mid to late May Late March to early May

Chris Sanders

Clematis alpina & C. macropetala 7 Selection guide by colour

Clematis ‘Pink Flamingo’ Clematis ‘Ruby’

Pretty, pale-pink, semi-double, Similar colour but less impact nodding flowers with darker than ‘Constance’. veins. Usually repeat flowers in August. Raised by Ernest Markham, 1937, C. alpina ϫ unknown. Raised by Elizabeth Jones, Introduced by George Brecon, Wales, introduced by Jackman & Son 1952 R J Evison c.1993. Mid April to early May Early to late May

Clematis ‘Rosy O’Grady’ Clematis ‘Tage Lundell’

A vigorous and distinctive Very distinctive foliage, new cultivar with spiky, lantern-like growth and foliage margins flowers in a pretty mauve- violet tinged. An interesting pink. flower colour.

Raised by Dr F L Skinner C. ochotensis ϫ C. alpina, Manitoba, Canada, pre 1964. raised by Tage Lundell of Helsingborg, Sweden. Mid April to mid May Early April to early May

Chris Sanders Clematis ‘Jacqueline Clematis ‘Jan Lindmark’ du Pré’ One of the earliest, distinct, Eye-catching cultivar with almost unique in colour. Dark large, rosy pink flowers, the maroon buds opening outer sepals of which are through shades of violet. strikingly margined silvery white. A seedling of ‘Bluebird’, raised in Sweden by Jan Raised by B Fretwell, Lindmark. introduced in 1985, named after the British cellist Late March to late April (1945–87).

Late April to May

Clematis ‘Constance’ Clematis ‘Columbine’

A seedling of ‘Ruby’ with A small, elegant flower freely flowers of a better size. produced; attractive green Distinctive and striking, very tipped staminodes. free flowering. Attractive contrasting light yellow green Raised by E Markham, foliage. introduced by George Jackman & Son in 1939. Raised by Ms K Goodman in 1986, named for actress Throughout April Constance Cummings (1910–2005).

Throughout April

8 RHS Plant Trials Bulletin Clematis macropetala Clematis alpina ‘Pamela ‘Wesselton’ Jackman’

Largest early, blue flowered Flowers consistently well. C. macropetala; a good leaf Distinctive narrow buds. and a first class plant; has the Many small blue flowers bluest of flowers. contrasting attractively with lime green foliage. Raised by James Fisk and named after his home village Raised by Rowland Jackman in Suffolk. of George Jackman and Son; named for his daughter. Late March to late April Throughout April

Clematis ‘Frankie’ Clematis ‘Frances Rivis’

Displays flower beautifully, Floriferous, distinctive broad, good vigour. deep blue sepals.

Raised by Frank Meechan in Raised by Sir Cedric Morris, Lincolnshire, introduced by introduced by Washfield R J Evison in 1991. Nursery.

Throughout April Throughout April

Clematis macropetala Clematis ‘Helsingborg’

An excellent un-named clone Extremely dark, small, shiny was in the trial, very free buds, a good dark flower. flowering and considered Attractive deep chocolate noteworthy. bronze stems and petioles, contrasting well with yellow The species was originally green foliage. brought to Europe by William Purdon in 1910, it is a native of C. ochotensis ϫ C. alpina, China, Mongolia and Russia. raised by Tage Lundell of Helsingborg, Sweden. Throughout April Late April to late May

Clematis ‘Pauline’ Clematis macropetala ‘Lagoon’ Rich violet blue colour, darker outer sepals result in dark A good garden plant which buds. performed well.

A chance seedling of Selected and introduced by C. ‘Frances Rivis’ at Washfield George Jackman and Son in Nursery, Hawkhurst, Kent. 1958.

Mid April to mid May Mid April to mid May

Clematis alpina & C. macropetala 9 Nomenclatural issues from the trial

Clematis ‘Frances Rivis’ Rivis’ as grown in the Netherlands has shorter, wider, The first published reference to this cultivar appears in the deeper blue sepals and is considered to be the true ‘Frances Journal of the Royal Horticultural Society 1966, in which it is Rivis’. Other accessions received for trial as ‘Frances Rivis’ announced that it has received an Award of Merit under were found to be seedlings or were considered to be ‘Blue the name of Clematis ‘Blue Giant’, exhibited by L. S. Dancer’, having typically long, slightly paler blue, lightly Fortescue, Esq; The Garden House, Buckland Monachorum, revolute sepals. S. Devon. Clematis macropetala ‘Maidwell Hall’ Clematis ‘Blue Giant’ is believed to have been derived from a plant grown by Mrs F. E. Rivis in her garden at Rosehill, Confusion in the trade concerning this cultivar was reflected Saxmundham, Suffolk under the invalid name C. alpina in the trial as only one of the four ‘Maidwell Hall’ entries thibetica. The seed was thought to have originally come was found to be true, two proving to be C. macropetala from Tibet or Nepal, however the range of C. alpina is not ‘Lagoon’ and another C. macropetala ‘Wesselton’. known to extend this far and was probably seed of C. ochotensis. Seed was given to Sir Cedric Morris by Mrs The history of this cultivar was outlined by G R (Rowland) Rivis and Clematis ‘Blue Giant’ was one of the seedlings Jackman in a lecture given on 29 July 1958 and transcribed raised. Cuttings were passed to Miss Hilda Davenport Jones in the Journal of the Royal Horticultural Society: of Washfield Nurseries, Hawkhurst, Kent, who renamed it ‘In 1956 we started the distribution of a C. macropetala form C. ‘Frances Rivis’ in 1968, (the name conserved by the under the name of C. macropetala ‘Lagoon’ and it is described International Clematis Registrar), subsequent to giving in our catalogue as “intermediate in colour between Oxford and material to Mr Fortescue. Cambridge blue”. We now find that an identical mutation was discovered twenty years ago by Mr Oliver Wyatt, of Maidwell The short, broad, dark blue sepals are distinctive, clearly Hall, Northampton. In future, therefore this particular form will seen in the photograph of the Award of Merit ‘Blue Giant’ be called ‘Maidwell Hall’. The name ‘Lagoon’ will be and ‘Frances Rivis’ as sent for trial by J. van Zoest. ‘Francis transferred to another form with flowers of a deeper colour.’

Clematis ‘Frances Rivis’ Clematis ‘Blue Giant’ Clematis ‘Blue Dancer’

Clematis ‘Lagoon’ Clematis macropetala ‘Maidwell Hall’ Clematis macropetala ‘Wesselton’

10 RHS Plant Trials Bulletin The following five cultivars had their names clarified. Suppliers of plants to the trial T H Barker & Son, Baines Paddock Nursery, Haverthwaite, ⅷ Clematis ‘Amethyst Beauty’ Ulverston, Cumbria LA12 8PF Raised in 1975 by M Johnson, the original invalid name Bridgemere Nurseries, Nantwich, Cheshire, CW5 7QB was ‘Amesthina’. Crowther Nurseries, Ongar Road, Abridge, Essex RM4 1AA ⅷ Clematis ‘Blushing Ballerina’ Denscombe Mill Nursery, Shillingford, Tiverton, Devon Entered in trial as C. macropetala ‘Alborosea’, an invalid EX16 9BH name; it was raised by M Johnson in 1974 from seed of The Guernsey Clematis Nursery Ltd, Domarie Vineries, a C. macropetala selection sent to him by R Horn-Gfeller, Les Sauvages, St. Sampson, Guernsey, GY2 4FD Switzerland. Goscote Nurseries Ltd, Syston Road, Cossington, Leicester Hewton Nursery, Bere Alston, Yelverton, Devon PL20 7BW ⅷ Clematis ‘Red Beetroot Beauty’ Hillier Nurseries Ltd; Ampfield House, Ampfield, Nr Originally named ‘Betina’, raised in 1980 by M Johnson. Romsey, Hants SO51 9PA Liss Forest Nursery, Petersfield Road, Greatham, Liss, Hants ⅷ Clematis ‘Claudius’ GU33 6HA Entered into trial with the unacceptable name of Robin Savill Clematis, no longer trading Clematis koreana ‘Citra’, this cultivar (‘Blushing Sheila Chapman Clematis, Ongar Road, Abridge, Essex, Ballerina’ ϫ C. koreana var. fragrans) was raised by RM4 1AA M Johnson in 1979. Sussex Clematis Nursery, 3 Stream Cottages, Horam, ⅷ Clematis macropetala ‘Chili’ Heathfield, Sussex, TN21 0HA Introduced in Sweden in 1922 from seed collected in Thorncroft Clematis Nursery, The Lings, Reymerston, Chili Province, China by Harry Smith, renamed Norwich, Norfolk NR9 4QG C. macropetala ‘Harry Smith’ by M Johnson. However it Treasures of Tenbury, Burford, Tenbury Wells, Worcs had not been validly published before the name ‘Chili’ WR15 8HQ was established. J. van Zoest B.V., Reijerskoop 148, 2771 BT Boskoop, Holland.

Acknowledgements Particular thanks are due to: Wendy Wesley (Trials Officer) for all the photographs in this bulletin (unless otherwise stated); Chris Sanders for his help and advice on the trial and also submitting photographs for this bulletin.

National Collections: National Collection of Clematis, Raymond J. Evison Ltd, Domarie Vineries, Les Sauvages, St. Sampson, Guernsey, GY2 4FD. National Collection of Clematis (Atragene Group), Mr M Oviatt-Ham, Ely House, Green Street, Willingham, Cambridgeshire, CB4 5JA.

Societies and websites The British Clematis Society www.britishclematis.org.uk The Membership Secretary, British Clematis Society, Elm Close, Binton Road, Welford-on-Avon, Stratford-upon- Avon, Warwickshire, CV37 8PT.

Further reading Clematis macropetala, Wisley clone Evison, R. J. 1998 The Gardener’s Guide to Growing Clematis. David and Charles, Timber Press Woody Plant Trials Sub-Committee 2005 Grey-Wilson, C. 2000 Clematis The Genus. BT Batsford Chairman: Peter Catt Jackman, G. R. Clematis. Journal of the Royal Horticultural Vice-Chairman: John Hillier Society, 89(1):11-16 Lloyd, C. 1965 Clematis. Country Life Chris Brickell David Clark Maurice Foster Matthews, V. The International Clematis Register and John Gallagher Michael Hickson John Humphris Checklist 2002. Royal Horticultural Society Roy Lancaster Chris Lane David Masters Toomey, M. and Leeds, E. 2001 An Illustrated Encyclopedia Chris Sanders Archie Skinner Harvey Stephens of Clematis. Timber Press

Clematis alpina & C. macropetala 11 The Royal Horticultural Society RHS Trials Bulletins The RHS is the UK’s leading gardening charity dedicated to Begonia Rex Cultorum Group: Number 16 advancing horticulture and promoting good gardening. Its Canna: Number 3 charitable work includes providing expert advice and Daisies (yellow perennial): Number 6 information, advancing horticulture, training the next Delphinium: Number 5 generation of gardeners, helping school children learn Fuchsia (hardy): Number 12 about plants, and conducting research into plants, pests Geranium (hardy) Stage 1: Number 10 and environmental issues affecting gardeners. The RHS Geranium (hardy) Stage 2: Number 14 AGM plant trial scheme is an important part of this work. Geranium (hardy) Stage 3: Number 18 Hyacinthaceae (little blue bulbs): Number 11 The RHS receives no government grants and for every Iris (bearded): Number 17 pound received from members’ subscriptions we need to Lavenders (hardy): Number 2 raise more than twice as much again to fund our charitable Miscanthus: Number 7 work. We also rely on donations and sponsorship to Peppers (sweet): Number 15 supplement income from our garden operations, flower Potatoes (salad): Number 8 shows, shops and plant centres. Potentilla (shrubby): Number 1 Rhododendron yakushimanum and hybrids: Number 13 Runner Beans: Number 19 RHS Plant Trials Saxifrages (silver): Number 9 With so many different types of gardener and so many Sedum (herbaceous): Number 20 different cultivars available to them in each group of Spiraea japonica (with coloured leaves): Number 4 plants, it is important that a system of recommendation is in place to help with selection at point of sale. These recommendations must be clear and reliable to ensure that RHS Plant Trials and Assessments of the thousands of plants available in the UK, a online publications, to complement the proportion are known to be excellent garden plants. The RHS Plant Trials Bulletins series RHS provides this information through its extensive Caryopteris: Number 2 programme of plant trials held at RHS gardens in the UK. Perovskia: Number 3 The RHS Award of Garden Merit signifies the selection Pittosporum tenuifolium hybrids and cultivars: Number 1 of the best cultivar for general garden use. Trials indexes can be obtained from The Trials Office, RHS plant trials serve the professional gardener who wants RHS Garden Wisley, Woking, Surrey, GU23 QB, to know the range of plants available, including the latest e–mail: [email protected] breeding and selection programmes, with their distinctive Trials reports on the web at characteristics and provenance. They also serve the www.rhs.org.uk/plants/award_plants.asp amateur who wants to know which plants will grow and perform well in a particular garden situation.

The RHS has an unrivalled resource of knowledge and expertise and is therefore best placed to conduct plant The RHS, the UK’s leading gardening charity trials for the UK gardening market. RHS Garden, Wisley Woking RHS Herbarium Surrey The RHS Herbarium keeps a record of trial cultivars as dried GU23 6QB specimens with detailed descriptions and photographic e-mail: [email protected] images. This forms an important reference for the horticultural industry. Any new cultivars are highlighted www.rhs.org.uk/trials and a nomenclatural standard specimen is preserved and described. Reg charity no. 222879 in Scotland SCO38262 The RHS Herbarium, stored at RHS Garden Wisley, is the largest active horticultural herbarium in the world. At present the collection contains about 80,000 herbarium All text and images Copyright RHS 2008 except where specimens and over 30,000 images of plants. Material is otherwise stated. actively collected from a wide spectrum of sources Illustration copyright Niki Simpson 2008 including RHS plant trials. ISSN 1477-9153 (print) ISSN 1447-9161 (online)

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