Scolymus is a genus of annual, biennial or perennial, herbaceous plants that is assigned to the family Asteraceae, and can be found in Macaronesia, around the Mediterranean, and in the Middle East. All species are spiny, thistle-like in appearance, with flowerheads that consist of yellow (rarely orange or white) ligulate florets, and canals that contain latex. It is sometimes called golden thistle or oyster thistle, and is known as سكوليمس (skwlyms) in Arabic and scolyme in French.
Description
The species of Scolymus are spiny herbaceous annuals, biennials or perennials of up to 1¾ m high, that contain a milky latex. These have twenty chromosomes (2n=20).
Root, stem and leaves
Biannual and perennial plants produce a stout taproot of up to 8 cm in diameter and 60 cm long. Young plants consist of a rosette of leaves, which may be variegated, once-pinnately spiny-lobed, to 30 cm long, and having short, fleshy stalks. The stems can be simple or carry many branches, and carry spiny wings along their lengths. The wavy leaves with prominent veins are pinnately divided and are alternately set along the stems. The leaf margin has prominent pale green or yellow veins and large teeth which are topped by fierce spines. The leaf surface may initially be covered in soft, felty hairs, which quickly clear away, most slowly on the veins.
Inflorescence, flowers and fruits
thumb|left|flowerhead of S. hispanicus with mites and beetles
thumb|cypselas encased in their paleae
The flowerheads are seated at the end of the stem or in the limbs of the higher leaves, are arranged in a spike or a globose cluster and are subtended by two to more than five leaflike bracts. Each flowerhead is circled by an involucre that consists of many spine-tipped bracts in several rows, the outer papery and shorter than the inner ones, which are leaflike in consistency. These surround the common floral base (or receptacle), which is conical in shape and is set with ovate papery bracts called chaff or paleae. Inplanted are dorsally compressed cypselas, each enclosed by a palea, the outer rows higher than the inner ones. On top of the cypselas there may be two to five stiff scabrous bristles, which are equivalent to sepals (and are called pappus). Also, on top of the cypsela and within the pappus is a yellow, orange or white strap-like corolla which ends in five teeth, together comprising a ligulate floret.
Etymology
The genus name Scolymus derives from the Greek σχόλυμος (skolymus) meaning "artichoke". Pliny used this name for Scolymus hispanicus. The species name hispanicus is Latin and means "from Spain", while maculatus is Latin and means "spotted", and grandiflorus is also Latin and means "large-flowered".
Distribution
- Scolymus grandiflorus occurs in Spain including the Balearic Islands and the Canary Islands, southern France including Corsica, Italy including Sardinia, Turkey, Lebanon, Libya, Algeria, Tunisia and Morocco.
- Scolymus hispanicus can be found from northwestern France southwards to Morocco, and in the east from Ukraine to Iran. It is also naturalized in Australia, United States, Argentina and Chile.
- Scolymus maculatus grows from Britain to the Canary Islands, throughout the Mediterranean eastwards to Iran. This species is naturalized in Australia and in North Carolina. The florets are pollinated by insects.
Use
thumb|left|leaves stripped to the middle vein for sale as vegetables
thumb|cooked egg on midveins of golden thistleAround the Mediterranean, such as in Portugal, Spain, Morocco, Italy, Greece, Cyprus and Turkey, the midveins of the rosette leaves of S. hispanicus, known in Spain as cardillo or tagarnina, are used as a popular wild food. It is generally gathered in April and May. These midveins are preboiled and lightly fried with garlic in olive oil. These serve as garnish for cocido. Fried cardillo is further combined with garlic, cured ham, and hard-boiled or scrambled eggs. Midveins are also used raw in salads. The roots are cooked and eaten, and compare in taste to salsify. Roasted roots have been used as a coffee substitute. Florets have been used as imitation saffron.
The root bark of S. hispanicus has been shown to contain the triterpenoid taraxasteryl acetate, and this substance is effective in suppressing spasms. In Turkey it is a component of a herbal elixir called lityazol çemil.
Studies have indicated that Scolymus might be used for the bio-removal of cadmium, with the highest concentration measured over 50 μg/g dry weight, and of methylene blue and Eriochrome Black T.