Ragusa knapweed
| Ragusa knapweed | ||||||||||||
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In a public garden in Corsica |
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| Centaurea ragusina | ||||||||||||
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The Ragusa knapweed ( Centaurea ragusina ), Dubrovnik knapweed or silver-leaved knapweed , is a species of knapweed ( Centaurea ) in the daisy family (Asteraceae) that grows in the Mediterranean area of the Dalmatian coast on sunny, maritime cliffs, rocks and stone walls.
features
The Ragusa knapweed is a perennial herbaceous plant that grows in a characteristic cushion shape; it reaches heights of growth of 30 to 50 (60) centimeters. The stem is erect, usually simple and leafless at the top. The flower shoots are terminal and lateral. The leaves are tomentose and pinnate. The flowers are yellow, the marginal flowers are not bright. The envelope flower appendages are triangular, small and have a bent back tip. Most of the leaves are in the rosette. They are slightly wavy and pinnately lobed with 4 to 7 egg-shaped, whole-edged or distantly toothed to lobed sections on both sides.
Flowering time is from (May) June to July.
The chromosome number is 2n = 18 or 20.
Systematics
In addition to the nominate form, the subspecies subsp. lungensis (Ginzberger) Hayek from the Kornati island of Dugi otok. Here it occurs in two varieties: f. baumgartneri (Ginzberger) Hayek with undivided leaves and f. padelini (Ginzberger) Hayek with partly undivided, partly pinnate and lyre-shaped leaves.
Location of the subspecies lungensis on Dugi otok
Occurrence
distribution
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The Ragusa knapweed is endemic to Croatia and is particularly limited to the islands of the central and southern Dalmatian coast. It is found on cliffs and natural stone walls on the Kornati islands in particular Dugi otok , as well as Šolta , Čiovo , Hvar , Sveti Andrija , Brusnik , Biševo , Vis , Sušac and Mljet . From the mainland only Marjan near Split, Palagruža such as Trpanj and in the vicinity of Cavtat (Konavoske stijene) are known sites.
The type locality of the first description by Carl Linné supposedly came from the area around Dubrovnik (formerly Ragusa), from which the species derives its scientific name. However, Visiani denied any spread around Dubrovnik. Linnaeus himself had named Epidaurum, the Greek name for Cavtat, as the place of distribution. Perhaps this is also the reason that later botanical textbooks indicated Crete as the distribution area, but where the species does not occur ( e.g. in Curtis's Botanical Magazine (1800), Plate 493 referred to as Cretan Centaury ).
Locations
As a cushion plant, the Dubrovnik knapweed inhabits steep, inaccessible cliffs near the sea or mortared natural stone walls. Due to the characteristic ecological niche as chasmophyte , sun plant and salt plant , which is perfectly adapted to the strong spray during hurricane-like storms ( bora and sirocco ) on the Adriatic coast, it is limited to a few locations of smaller islands and steep cliffs of the mainland coast, which geologically mostly from Cretaceous massive limestones are built up. Exceptionally, however, it is also found in large numbers on eruptive masses and volcanic breccias on the island of Brusnik. In terms of plant sociology, it forms part of the endemic limestone crevice formation Phagnalo-Centaureetum ragusinae .
Dubrovnik knapweed on the mega-cliff of Konavoske stijene in the middle distance. It settles here on the middle and upper cliff areas that are not as badly affected by the salt spray
The Dubrovnik knapweed, in the picture at the bottom left on the rock, is one of the most characteristic plants on the Cretaceous limestone cliffs of the Konavoske stijene south of Cavtat in the Konavle
use
The Ragusa knapweed is rarely used as an ornamental plant for summer borders and edging. It has been in culture since 1710 at the latest. The 'Magic Silver' variety reaches heights of 20 to 35 centimeters.
Individual evidence
- ^ A b c Eckehart J. Jäger, Friedrich Ebel, Peter Hanelt, Gerd K. Müller (eds.): Rothmaler Exkursionsflora von Deutschland. Volume 5: Herbaceous ornamental and useful plants . Spectrum Academic Publishing House, Berlin Heidelberg 2008, ISBN 978-3-8274-0918-8 .
- ↑ a b c d e f g Čedomil Šilić: Endemične biljke (= Priroda Jugoslavije. Volume 4.) Svjetlost, Sarajevo 1990, ISBN 86-01-02557-9 , p. 154.
- ↑ a b Lujo Adamović 1929: The flora of the Adriatic countries . Gustav Fischer, pp. 78 and 156
- ↑ Centaurea ragusina at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ^ A b August Ginzberger: Systematics and distribution of Centaurea ragusina and lungensis . Assembly of the Zoological-Botanical Society, 83, report of the Botany Section. Meeting on May 26, 1933, p. 6 PDF