Artemisias in British cultivation

Contents

Introduction

Historically there have been relatively few artemisia species in cultivation in Britain until the late 20th century and when the Artemisia Collection started there were perhaps only 15 species or cultivars widely grown in gardens. Historically those that were grown from Medieval times were wild species or selected forms which had herbal or other uses. Thus of the British natives, Artemisia absinthium (wormwood) had long been grown for its properties as a vermifuge, rather than as an attractive garden plant, and whilst strains may have been selected, cultivar naming does not appear to have taken place until the mid 20th century. Mugwort  (A. vulgaris) has been grown for centuries as a bittering agent for “mugging” ale before the use of hops became widespread. Perhaps the first foreign introduction to our gardens was the cottage garden southernwood (A. abrotanum hort.), supposedly called “southern” to indicate a southern European origin and distinguish it from the native wormwood. Tarragon (A. dracunculus group) has been grown in British gardens as a flavouring herb for many years with two distinct types having become accepted over recent decades. Thus the “Russian” form refers to a rather coarse, strong growing plant lacking in flavour, whilst the “French” form is a  smaller, more weakly growing and more tender form with a superior anise flavour. Here the country descriptors owe more to our copying foreign culinary tradition as the “French” form probably originates in central Eurasia and was certainly never native in France. 

Attractive artemisias have been collected from the wild in the UK and abroad by plant collectors and keen gardeners over recent centuries. The native sea wormwood (A. maritimum) appears to have been used as a silver plant in gardens over a long period and John Tradescant brought back a “broad leaved” form of it from the Isle de Rhé in France from the time when he was acting as a military engineer at the seige of La Rochelle (1625). His plant lists of 1629-34 contain eight artemisias which appear to equate to; abrotanum, absinthium, arborescens, austriaca, caerulescens, crithmifolia, dracunculus and maritima.

The RHS has bestowed the Award of Garden Merit (AGM) on several cultivars or forms, mainly in 1993 as a result of the Artemisia plant trial of 1991-2. In some cases where there are several different clones, it may be difficult to now determine whether the award is for a particular form or the entire group.

Main garden plants and cultivars 

The following is a list of species or cultivars that are more widely grown in UK gardens, or are becoming more popular. The National Collection holds many more species and forms than are listed here.

  • abrotanum (AGM) The “cottage garden” southernwood has reputably been grown in gardens in UK since before 1548. The clone most widely grown is a shrub to three feet (90cm) that has a well known pleasant, rather lemony smell, and dried leaves were used to deter moths from stored clothes. It rarely, if ever flowers in UK. The origin of this plant is unclear and wild forms ofabrotanum usually flower freely in cultivation. The camphorated southernwood is a form of A.alba.
  • absinthium(wormwood) Native forms tend to be grey-green, and grows to four feet (120cm) or so. Forms from hotter regions may appear more silvery, and montane forms can be shorter. Three cultivars are now associated with the garden of Mrs Fish.
    • 'Lambrook Silver (AGM) is a silver plant shorter than most forms which generally grows to about two feet (60cm) and it or a seed parent was probably collected abroad.
    • 'Lambrook Giant' is much taller and less silver and may be a native form.
    • 'Lambrook Mist' (AGM)is a more recent form (selected from the Artemisia trial 1991-2) that is taller and perhaps whiter than 'Lambrook Silver'. One problem with most artemisias, and wormwoods in particular, is that the flowers often spoil the appearance of the foliage.

Most wormwoods flower from July through to August, but plants can often be kept silver for longer if the flowering stems are removed.

    • 'Silver Ghost' is a recent selection from the National Collection that flowers late August to September and thus holds its silver appearance for longer.
    • 'Persian Lace' is another selection from the Artemisia National Collection, which has a more deeply cut, delicate absinthium leaf form.
  • afra is one of the few Artemisia species that occur in the southern hemisphere, extending into South Africa. It is a erect (to 4ft, 120cm) shrub with attractively cut grey/green leaves. 
  • alba is a somewhat variable plant from central Europe. Two main cultivars are reputed to derive from wild variants.
    • ‘Camphorata’ is the camphor scented southernwood.
    • ‘Canescens’ (AGM) is the “wire netting plant” with long twisting silvery leaf lobes. It is occasionally, wrongly, sold as ‘Splendens’.
  • arborescens is a taller (to five feet, 150cm) silver leaved shrub of Mediterranean origin. Forms differing in size, leaf form and scent occur in different locations and at different heights above sea level. The plant has been widely used, spread and intermixed by the activities of man, particularly around the times of the Crusades and it is often found associated with ruined forts etc. There are many different forms or clones in cultivation.
    • 'Brass Band' is a cultivar identical to 'Powis Castle' but nothing has been found out regarding the naming or history of this plant. If the name predates 1968 it is possibly the (UK) source of 'Powis Castle' qv.
    • 'Faith Raven'. The original Faith Raven was collected as a seedling by John and Faith Raven from arborescens growing near the monastery on Mt. Filerimos, Rhodes in 1968 or '69. Unfortunately it has become muddled with two plants now appearing under that epithet. One of these (probably the correct form) is a tall 4ft (120cm) typical arborescens type plant similar to material more recently collected from the original site. The other form in trade is identical to 'Powis Castle'.
    • 'Huntington' is a US named variety intermediate between arborescens and absinthium but taller than ‘Powis Castle’ and more freely flowering. It appears to have been derived from one of several variants held at the Huntington Botanic Garden (San Marino, CA) but staff there are unsure of which of their clones might be the origin.
    • 'Porquerolles' is a short form 16” (40cm) selected (1986) by John Simmons (Kew), later named by Brian Halliwell, from variants growing at the Porquerolles Botanic Garden in the south of France.
    • 'Powis Castle' (AGM) is probably the best known silver artemisia cultivar in the UK. It is a short 18” (45cm) form intermediate between arborescens and absinthium or possible a hybrid. It rarely flowers in UK. The original source is unknown but Jim Hancock informed me that he obtained a cutting in about 1968 or '69 from a Yorkshire garden open under the NGS scheme. He took it with him to Powis Castle when he became Head Gardener there in 1972 and it was later (c1974) named from that garden by John Sales or Graham S Thomas to help to promote National Trust gardens.
gorgonium 2A. arborescens gorgonium

 

Similar large silver shrubs occasionally grown are the island endemics argentea (Madeira), thuscula (syn. canariensis, from Canary Isles) and gorgonium (Cape Verde Isles).

 
  • californica is an eversilver (grey/green) shrub to 2 feet (60cm), recently introduced from the Californian sierras. The original import has a very attractive sweet fragrance, but a later introduction has a more camphorous odour. A prostrate version of the sweet smelling plant ‘Canyon Gray’ has also been introduced, but it appears to be less hardy.
  • caucasica (AGM) is a low growing, mat forming, silver alpine which is useful in the rock garden. Several slightly different forms have been grown and variously known asassoanalanata or pedemontana.
  • dracunculus Two forms have been grown in UK gardens as “French” or “Russian Tarragon” as described above.
  • glacialis is a similar mat forming alpine to caucasica, but is a name sometimes wrongly applied to various other forms.
  • lactiflora (AGM) White mugwort. This herbaceous plant (4 feet, 120cm) has leaves similar to mugwort but is grown for its creamy white flower stems. The green form, collected by Ernest H. (Chinese) Wilson, has been grown in UK gardens since around 1902, but the more recent Guizhou form (A. lactiflora 'Guizhou') with more bronzy purple leaves was collected in Guizhou province, China, in 1985 by John Simmons (RBG Kew). These forms have been joined in the Artemisia Collection by a further white flowered species from the Far East, namely A. anomala. This species is unlike most artemisias in having entire (ie uncut) leaves.
  • ‘Little Mice’ see vallesiaca.
  • ludoviciana North American stoloniferous herbaceous plants, with grey green through silver to white leaves. Typically 2-3 feet (60-90cm) high. Various forms occur with differing leaf forms from simple entire willow like through various cut-leaved forms to broader leaves. Some whitish entire leaved forms appear to have been known as gnapholodes or purshiana in the UK.
    • 'Silver Queen' (AGM) is a form with prettily cut basal leaves (introduced 1930's?) 
    • 'Valerie Finnis'(AGM) is a form of ludoviciana (often referred to as ludoviciana- latiloba), or douglasiana. It was brought to England by Valerie Finnis in 1950 who obtained it from the Munich Botanic Garden where it was grown (wrongly) as A. borealis. It was given by Valerie Finnis to Beth Chatto who bestowed the name.
  • maritima (syn. Seriphidium maritimum) The sea wormwood is a pretty native coastal saltmarsh shrub (12” 30cm) which has been valued as an ornamental shrub for centuries and grows well in good garden soil. Several forms of differing leaf form or habit have been cultivated and variegated forms occasionally occur. (The author found one near Wells by Sea, Norfolk in 2007.) It is often sold under a variety of wrong names.
  • ponticaroman (wormwood). A grey-green low growing (18” 45cm) herbaceous plant with doubly cut leaves, which may have been grown in the UK since the time of the Tradescants.
  • schmidtiana / schmidtiana 'Nana’ (AGM) is a herbaceous silver plant to about 9” (23cm) that dies down in the winter. The stems are erect and form flowering panicles. A low growing form of caucasica is often wrongly sold as schmidtiana 'Nana’.
  • stelleriana A low growing (to 18” 45cm) shrubby plant with large simply cut white felted leaves. A shoreline plant from the far east grown in UK for perhaps a couple of centuries and reputed to be naturalised on some beaches in Devon or Cornwall.
    • 'Boughton Silver' (previously Mori's form) is a largely prostrate form with prettily cut leaves. The original was given to Valerie Finnis by Mr Mori of Japan in 1970. This plant was later taken to North America where it was renamed and reintroduced as 'Silver Brocade'.
    • 'Nana' is an earlier named cultivar that has slightly more a upright habit and tends to grow upwards and flop amongst taller perennials, giving a white background to other plants.
  • tridentata (syn. Seriphidium tridentatum) Several versions of the larger North American sagebrushes have been grown in the UK such as the ssps. tridentata and vaseyana. These are large eversilver shrubs at 4 feet (120cm) or more, but they will only survive our winters in well drained soil. One notable cultivar is ‘Dove Creek’, but vegetative propagation is very difficult and most plants are seed grown.
  • vallesiaca (AGM) is a low growing shrub similar to maritima, but with more delicate leaves. It became popular in the late 1980s. There are a few slightly different forms in cultivation. A more crumpled leaved form probably grown since the 1950s was wrongly named villarsii. An identical plant has been reputably discovered as a chance seedling by Dutch growers (1996) and reintroduced as ‘Little Mice’. (It is already appearing in trade as ‘Tiny Mice’.)
  • vulgarisThe common mugwort is a widespread wayside weed in UK growing to about 5 feet (150cm). It is somewhat variable in leaf form and habit and several different types could be described in Britain. Wider variety occurs in the Far East where many further species are described, varying in leaf form, habit etc. Some cultivars have been selected in Europe (eg ‘Rosenschleier’). Variegated forms occur spontaneously, some of which have been developed as cultivars.
    • ‘Variegata’ is an old established cream variegated form
    • ‘Oriental Limelight’ is a recently trade marked plant with strong yellow streaks.
    • ‘Cragg-Barbereye’ and ‘Peddars Gold’ were yellow variegated forms originally found in Wiltshire and Norfolk respectively. Both were somewhat difficult to propagate and maintain and may have now died out from the nursery trade.
Dr J D Twibell
Plant Heritage/NCCPG Artemisia Collection

Back