Plant of the Week – 24th August – Giant Scabious (Cephalaria gigantea)

by Roger West

Cephalaria gigantea, flower and seed head. Photos: John Grace. see more pictures at http://www.seasonalwildflowers.com/giant-scabious.html

Cephalaria gigantea (Ledeb.) A.V.Borov. is a larger relative of Knautia (Field scabious), which it greatly resembles, but differs by having bracts subtending each flower and an eight-toothed epicalyx instead of a four-ridged one (Stace, 2019).  Its light-yellow inflorescences can be up to 6 cm diameter.  Its leaves are large and entire to pinnately lobed.  It is native to southern Europe and Keith Jones says was introduced to the British Isles for horticulture in 1750, becoming naturalised in 1920 (http://www.seasonalwildflowers.com/giant-scabious.html).  The BSBI distribution map shows quite a few records from the 1950s. There are about 25 records in Scotland, mainly in the east and south. Smith et al (2000) mention a record from Gorebridge 1956 and one from Gullane in 1957; they also refer to a 1978 record in Buckstone sandpit, Edinburgh. This 1978 location corresponds to the north-east corner of Fairmilehead Park: Giant Scabious is no longer there. In England, the species has a slightly denser but still sparse distribution (hardly any records in Wales), but climate warming may encourage its spread.    These records seem likely to be garden escapes or throw-outs, and their descendants.

Dense stand of C. gigantea near Lothianburn Junction, Edinburgh. Photo: John Grace

Stace places it in the Dipsacaceae, which is well justified by its resemblance to Knautia, Succisa and Scabiosa, but the RHS and BBC Gardeners’ World websites place it in the Caprifoliaceae, a family which Stace says is “Paraphyletic due to exclusion of [Valerianaceae] and [Dipsacaceae]”.  Stace does not mention its synonyms, S. tatarica and S. caucasica, presumably because their usage is purely horticultural.

It is native to southern Europe, western and central Asia and northern and southern Africa. It is an important component of Caucasian grasslands and high mountain vegetation.

British websites about it are dominated by nurserymen who would like to sell it to you.  Horticulturalists tell us that it likes partial shade or full sun, a south, east, west or north-facing aspect, and that it prefers clay, loam, sand or chalk soils that are acidic, alkaline or neutral and moist but well drained; it is evidently not very fussy!  It is tall for an herbaceous plant, up to 2.5 m, and is a hardy perennial.  It has a basal cluster of large, divided leaves that arises from a woody rootstock.

The genus Cephalaria was named by Heinrich Schrader (1767 – 1836), a German botanist.  He also named the Australian genus Hakea and published Nova genera plantarum (1797) and Flora germanica (1806).  The genus Schraderanthus is named in his honour.  C. gigantea was first named by Carl von Ledebour (1786 – 1851) a professor in the University of Tartu, Estonia, whose most important works were Flora Altaica, the first Flora of the Altay Mountains (1833) and Flora Rossica (1841–1853), the first complete flora of the Russian Empire; species he described for the first timeincluded Pyrus sieversii (now Malus sieversii), the wild ancestor of the apple, and the Siberian Larch, Larix sibiricaC. gigantea received its present name from A. V. Bobrov (born 1969), a Russian botanist and explorer.  A summary of the taxonomic history of Cephalaria is included in Göktürk and Sümbül (2014),  The name Cephalaria is derived from Greek kephale, a head, but I don’t know why it was bestowed by Schrader.  The only monographs I have found in google.scholar are Szabó (1940) and the revision of the genus in Turkey by Göktürk and Sümbül (2014), which describes 39 species, of which only C. gigantea has entered the British flora.

Geographical distribution according to GBIF—the Global Biodiversity Information Facility (reproduced in accordance with GBIF terms and conditions)
Strangely, GBIF does not show the African distribution at present

C. gigantea has been used in traditional medicine in the Kars province of Turkey for the treatment of urinary, menstrual, rheumatic, pulmonary and cardiac diseases it is native as a sedative and anti-inflammatory remedy (Tabatadze et al., 2007).  Cephalaria spp., including C. gigantea, contain a great variety of compounds with anti-leishmanial, anti-fungal, anti-protozoal, anti-convulsant and other pharmacological properties (Caliskan et al., 1994).  In Antalaya, the fruiting capitula of C. balansae are used to treat epigastric burning.  However, I am not sure whether any of these compounds have entered the modern pharmacopeias of the countries where they were researched, or of western Europe. 

The flowers of C. gigantea have traditionally been used in the Caucasus for dying woollen rugs, and the seeds of C. syriaca Schrad. are ground with flour to delay the staling of bread.  There have been a large number of papers on the biochemistry of Cephalaria spp. published in Russia, South Africa and points between, many of them naming compounds whose names will not fit onto one line: I doubt that many readers of this PotW would find them of interest.   If you are, you can locate them on google.scholar.

The dense leaf canopy casts deep shade and prevents establishment of other species. Photo: John Grace

Besides being a handsome plant of herbaceous borders, C. gigantea has one possible use.  This plant spreads slowly, but it does spread.  The Gardeners’ World website states that “Although tall, Cephalaria gigantea isn’t overbearing – its finely cut, aromatic leaves and stems are airy, allowing for growing in a range of planting schemes”, but when I found a patch of C. gigantea near my home, I saw that it had succeeded in thrusting Urtica dioica aside by overtopping its rival and depriving it of light.  It must be pretty competitive below ground as well as above, to have prevailed against U. dioica.  I therefore decided1 to try it against Petasites japonicus ssp. giganteus (Giant butterbur) which is an invasive alien in Braidburn Valley Park, whose eradication, although deemed essential and encouraged by the City of Edinburgh Parks Dept., had proved to be a labour of Sisyphus for the Friends of Braidburn Valley Park (small fragments of its rhizome sprout vigorously).  I was, at that time, a member of the committee of FBVP.  I therefore decided, with approval, to try C. gigantea against P. japonicusC. gigantea produces abundant seed which has a high germination rate, but its seedlings are not competitive against rank vegetation, which may be why it is uncommon as a wild plant.  It is therefore necessary to cultivate them until they are robust, then plant them out judiciously, an activity which might commend itself to volunteer conservationists.  I grew C. gigantea seedings for three years until they were sturdy, then planted some among the butterbur.  I noticed a few weeks ago that, after a further three years, they were now competitive against the butterbur and were showing signs of thrusting it aside.  I await further developments with interest, but Cephalaria gigantea may be found valuable for the suppression of some invasive aliens. 

High-resolution image of the seed head showing the bracts of each floret very well, recalling the structure of the (related) teasel. Phot: Chris Jeffree

1Editors’ footnote

Readers should be aware that there are strict laws regarding the planting of non-native species in the wild. Scottish Law is very clear about this:

https://www.sepa.org.uk/environment/biodiversity/invasive-non-native-species/
https://www.gov.scot/publications/non-native-species-code-practice/pages/5/

Although parks are exempt, there remains a responsibility to prevent aliens spreading beyond the park.

Readers are reminded that views expressed in our blogs do not represent the official policies of the Botanical Society of Scotland but those of the authors themselves.

References:

Caliskan OA, Anil H, Stephenson GR. (1994).  Cephalaria saponin A, a new bidesmosidic triterpene saponin from Cephalaria transsylvanica. J Natural Products. 57: 1001-03.

Göktürk, R.S. and Sümbül, H. (2014).  A taxonomic revision of the genus Cephalaria (Caprifoliaceae) in Turkey.  Turk. J. Bot. 38: 927-968.  doi:10.3906/bot-1310-6.  This paper can be read freely, in its entirety, at:  http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.675.6322&rep=rep1&type=pdf

Stace CA (2019) New Flora of the British Isles. C&M Floristics.

Szabó Z (1940). Cephalaria-genusz monografiaja. Budapest, Hungary: Kiadja A Magyar Tudomanyos Akademia Press (in Hungarian).

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