Chamaeleon is a genus of thistle-like perennial plants in the Asteraceae family (tribe Cardueae, subtribe Carlininae), described by French botanist Henri Cassini. The genus is native to a broad range from the Western Mediterranean eastward to Pakistan. Plants are characterized by a growth form with spiky, radiating leaves and a notably stemless inflorescence — the pinkish capitulum (flower head) of threadlike florets arises directly from the basal rosette surrounded by spiny bracts, rather than atop a flowering stem. A long rhizome anchors the plant, and ripe fruits may exude a white or yellowish gummy latex. Five species are accepted, the most widely documented being Chamaeleon gummifer (distaff thistle), which also has a history of folk medicinal use despite being dangerously toxic due to atractyloside and carboxyatractyloside glycosides.
Etymology
The genus name Chamaeleon is derived from Greek χαμαιλέων (chamailéōn), meaning "chameleon" — from χαμαί (chamaí, "on the ground") and λέων (léōn, "lion"), literally "ground lion." The name was applied by Cassini; in classical antiquity "chamaeleon" was used for a thistle-like plant.
Distribution
The genus ranges from the Western Mediterranean basin — including the Iberian Peninsula, Italy, Greece, Malta, and Northern Africa — eastward through the Middle East to Pakistan. Species occupy a variety of habitats from cultivated fields and shrublands to forests and rocky terrain.
Ecology
Species grow in diverse habitats including cultivated and uncultivated fields, shrublands, forests, and rocklands, on various substrates. The plants produce a gummy latex from the rhizome when fruiting, and flower in late summer or early autumn. They are insect-pollinated, with capitula composed of many small threadlike disc florets.
Conservation
Chamaeleon gummifer, the most widespread and documented species, is rated as Least Concern on the IUCN Red List. No specific conservation assessments are recorded for the other four accepted species.
Cultural Uses
Chamaeleon gummifer has a history of use in folk medicine, particularly in the Mediterranean region. However, the plant is extremely toxic — at least 98 fatalities occurred due to poisoning in Morocco between 1981 and 2004, most in children. Accidental ingestion has occurred through confusion with edible artichoke thistle or through use of the plant's gummy latex as chewing gum. Toxicity is caused by two glycosides, atractyloside and carboxyatractyloside; there is no specific antidote.
Taxonomy
The genus was described by Henri Cassini and is placed in the Asteraceae family, tribe Cardueae, subtribe Carlininae. Chamalium Cass. is treated as a synonym. Species now in Chamaeleon were formerly classified under Atractylis or Carlina. GBIF lists two descendant species while Plants of the World Online (cited by Wikipedia) accepts five: C. comosus, C. cuneatus, C. gummifer, C. macrocephalus, and C. macrophyllus.
