Alpine Garden Society



01386 554790
Back to List of Entries for Kent Alpine Gardener's Diary

Go to bottom

You can add your comments on the content of this diary entry by starting a discussion, but you need to login first
Login

Kent Alpine Gardener's Diary

This entry: 18 December 2017 by Tim Ingram

'Thistles for the garden' - Steve Law

'Thistles' - talk to the East Kent AGS, 13th October 2017

'In California and the neighbouring States are several species of the genus Cirsium, which have rich scarlet flowers, and the introduction of these is much to be desired. From the description of these to be found in the various "Floras," C. arizonicus is, perhaps, the most brilliant, but until that species is introduced, we must be content with the plant under notice, C. occidentale var. Coulteri, a most striking and decorative subject, growing five feet high, stout and straight, clothed throughout - leaves, stems and flower-heads - in soft, white, cottony wool, and producing its soft scarlet flowers from the axils of every leaf.'

[Thomas Hay, 'Plants for the Connoisseur',  1938]

(this illustration is from Wikimedia, licenced under Creative Commons:

https://commons.wikimedia.org/wiki/File:Cirsium_occidentale_candidissimum_(5377723079).jpg)

 

'Thistles' - talk to the East Kent AGS, 13th October 2017

'In California and the neighbouring States are several species of the genus Cirsium, which have rich scarlet flowers, and the introduction of these is much to be desired. From the description of these to be found in the various "Floras," C. arizonicus is, perhaps, the most brilliant, but until that species is introduced, we must be content with the plant under notice, C. occidentale var. Coulteri, a most striking and decorative subject, growing five feet high, stout and straight, clothed throughout - leaves, stems and flower-heads - in soft, white, cottony wool, and producing its soft scarlet flowers from the axils of every leaf.'

[Thomas Hay, 'Plants for the Connoisseur',  1938]

(this illustration is from Wikimedia, licenced under Creative Commons:

https://commons.wikimedia.org/wiki/File:Cirsium_occidentale_candidissimum_(5377723079).jpg)

 

(twice by courtesy of cyberspace!)

Within the huge family of plants Asteraceae, the thistles make a highly significant and distinctive sub-family of 2500 species in some 80 genera (the Carduoideae). In common name they are often despised and regarded as weeds by gardeners - and many are - but looking at them more closely, as Steve Law of Brighton Plants did in his talk to us in October, shows not only how varied and fascinating they are but how many can make potentially interesting plants in the garden. For me there is a parallel here with the Umbellifers - the Apiaceae - an important family of plants of similar overall size, often not recognised by gardeners for its ornamental merits compared with culinary and medicinal.

The emphasis of his talk was really more botanical than as examples of cultivation in the garden, because very many - taken from information available on the Internet - are just not available or grown. But for the plantsman this is part of the very motivation of gardening, to learn more and experiment more widely with plants, and Steve showed many such enticing examples (some of which are referred to below).

This is Cynara cardunculus, the familiar Cardoon, a form growing in our garden ex. the Chelsea Physic Garden and from Graham Gough at Marchants Perennials. However, there are a number more smaller and very interesting species in the genus, some of which Steve Law grows and sells from his nursery Brighton Plants, which would suit hot and dry situations in rock gardens and sunny banks.  Cynara cardunculus subsp. flavescens, for example has striking and formidable 'yellow' thorns that make it very distinct from the type species http://josenaturaleza.blogspot.co.uk/2013/07/cynara-cardunculus-l-subsp-flavescens.html.

Cynara baetica (C.hystrix) and C.humilis are smaller again, the former with colourful pink spiky bracts, and the latter with a very distictive and attractive white form, alba, which is very rarely grown - rather beautifully pictured here http://flora-on.pt/index.php#1Cynara+humilis.

Most exciting of all for the alpine gardener is the stemless species Cynara (Arcynatournefortii which gives an entirely different perspective on the genus http://flora-on.pt/index.php#1Cynara+tournefortii. Like many composites these Cynara produce a lot of infertile seed and tend to be self-infertile in gardens due to protandry, so unless grown more widely will remain rare and reliant on irregularly available wild sources of seed, and cultivation by specialist growers. Steve Law kindly distributed seed of a couple of species to the audience.

Stemless thistles are amongst those most prized by rock gardeners, and there are many examples: species of Carduncellus, Carlina acanthifolia and C. acaulis, and the amazing Onopordum acaulon http://www.apatita.com/herbario/Asteraceae/Onopordum_acaulon_subsp_acaulon.html. 

The genus Centaurea is rich in small and rarely cultivated species, many of which do not have the spiny habit of thistles, but others that do - Steve mentioned in particular C. eryngioides (here pictured on Flora of Israel Online), which from its name shows how a similar habit has arisen within the unrelated family Apiaceae, with species of Eryngium, http://flora.org.il/en/plants/CENERY/

Other more familiar thistles are the biennial Ptilostemon and Galactites which can be stunning in the garden for their overwintering rosettes and in dry open places will often self-seed reliably from year to year. These pictures taken today show Galactites tomentosa growing with cistus and rock roses in our garden at Copton Ash in Faversham.

Cardopatium corymbosum is extraordinary and compelling for its hemispheres of deep-blue flowers http://www.greekflora.gr/el/flowers/1568/Cardopatium-corymbosum, and another Greek thistle, Carlina tragacanthifolia, for its uncompromising spinyness! These are hardly plants for any but true Mediterranean gardens which receive long hot and dry summers, but they reveal an underlying characteristic of thistles and one which can be a feature of similar but less severe situations in the UK, and particularly rock and gravel gardens.

So many thistles are plants of dry and arid landscapes and not of interest to any but the most adventurous and botanically-minded gardeners, willing to experiment. To counter this impression Steve Law finished his talk by looking at Eurasian mesic environments which do contain species much more relevant to many gardens in the UK. These plants - a well known example is Cirsium rivulare 'Atropurpureum', so widely grown and requiring quite moist and fertile soil - do have particular potential in future plantsmen's gardens. Four examples are other species of Cirsium, C. erisithales, C. waldsteinii, C. borealinipponense, and C. purpuratum, the last described here in 'A long time developing' in a Botanics Story from the Royal Botanic Garden at Edinburgh https://stories.rbge.org.uk/archives/8393). These plants from wetter places quite commonly have nodding flower-heads, good examples being Synurus pungens and the dramatic Alfredia cernua, and Saussurea frolowii from Siberia. They are often dramatic plants but perhaps rather disturbingly reminiscent of Burdock, and a long way from the rock garden, closer to the view of thistles as weeds than as ornamentals. But if your interest in plants is in their variation and diversity then they deserve recognition, and some could prove valuable and effective new introductions to gardens.

Maybe gardeners are quite ambivalent in their perception of thistles but this quote from Henry Ward Beecher gives them the benefit of the doubt:

 'The thistle is a prince. Let any man that has an eye for beauty take a view of the whole plant, and where will he see a more expressive grace and symmetry, and where is there a more kingly flower?'

Go to top
Back to List of Entries for Kent Alpine Gardener's Diary

You can add your comments on the content of this diary entry by starting a discussion, but you need to login first
Login