Nomenclature

Species name:

Cheirolophus crassifolius   (Bertol.) Susanna

Author(s):

Antonio Bertoloni
   Italy, 1775-1869

Alfonso Susanna
   Spain, 1956 -

Common name:

Maltese Rock Centaury
Malta Knapweed

Maltese name:

Widnet il-Bahar

Plant Family:

Asteraceae / Compositae   (Daisy Family)

Name Derivation:

Cheirolophus = One source gives 'cheiri' as red-flowered, while another says it means a hand. The term 'lophus' means a crest of tufts. The most logical explanation would be that the genus means a "red-flowered crest" referring to the shape of the red-purple flowers with a crest-like tufts. (Greek);

crassifolius = Thick-leaved (Latin).

Synonyms:

Palaeocyanus crassifolius, Centaurea crassifolia, C. spathulata Some authors insist that Palaeocyanus crassifolius is the actual species name; not Cheirolophus crassifolius.

Remarks:

An endemic species and selected as the National Plant of Malta. It is listed as highly endangered species for extinction by several references such as The Top 50 Mediterranean Island Plants by IUCN, published in 2005.

Plant Description

Life Cycle:

Perennial

Habitat:

Coralline limestone cliffs and elevated valley sides.

Sources in Malta:

Scarce, found at the Southern coastal cliffs of Malta, such as Wied Babu, Fawwara and Dingli and also present in few cliffs at Gozo such as Ta' Cenc and Dwejra.

Plant Height:

50-70cm

Flowering Time:

End of May - Jul

This plant forms stems with several basal branches and sub-branches and as a result it takes the growth form of a shrub, about 40-60cm high. Its common to find the curved lower stems tangled in each other in older and larger specimen. The stems are glabrous and the lower part usually becomes woody.

The leaves are seen along rocky limestone cliffs throughout Winter and Spring. They are normally found arranged as rosettes along the upper parts of the stems and their arrangement becomes alternate downwards the stalk. The leaves at the lower part of the stems falls off in adult plants. They have a spathulate shape, that is, they gradually become narrow downward from a broad rounded summit - like the shape of a spoon. The leaves are thick (2mm), smooth on touch, glabrous and with an entire outline. No venation is visible except the central vein. Their measurement vary according to age but mostly fall in the range of 6-8cm long by 1-2cm wide. Leaves along the long flowering stem are smaller and thinner.

The flower is a capitulate head composed of 5-6 rows of involucral bracts (=phyllaries) and a top of numerous tubular florets having a characteristic purple colour. No ray florets are present. The partially overlapping, glabrous phyllaries are oval with maroon tips. The flower head is about 30-40mm long (including the involucre) and about 35-50mm across. The slightly fragrant smell of the flower somehow resembles that of tea.

Each floret consists of a tubular structure (9-10mm long) which sits on the flat receptacle at one end, and opens up into 5 thin petals (7-8mm long / 0.8mm wide) at the other upper end. The thin lilac-white style protrudes out from the floret by about 7-8mm. There are 5 fused stamens around the style which are same colour and rather inconspicuous.

When the seeds get ripe, the drying involucre spreads open like a plate and so, it exposes the receptacle that holds tightly the numerous, pappus-bearing achenes (seeds) to the wind. When fully mature, seeds detach from the receptacle and are carried away by wind. The achenes are silver-beige, 3mm long and linear; while their bristly pappus is straw-coloured, beakless and about 7mm long.

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