Cynoglossum is a genus of flowering plants in the borage family, Boraginaceae, placed in the order Boraginales. The genus was established by Linnaeus in his foundational work Species Plantarum (1753) and currently encompasses approximately 81 accepted species. Its members are herbaceous plants bearing characteristically small flowers and distinctive hooked or bristled nutlets (mericarps) that function as effective burrs, clinging readily to animal fur, wool, and clothing — an adaptation that aids seed dispersal.
The genus has a wide natural distribution spanning Eurasia, Africa, New Guinea, and Australia, reflecting its success across a broad range of temperate and subtropical habitats. The best-known member, Cynoglossum officinale (common hound's-tongue), is native to Europe, Asia, and parts of Africa and has become a troublesome introduced weed in North America, where its burs entangle sheep wool and its foliage, containing pyrrolizidine alkaloids, is toxic to cattle and other grazing animals — causing liver damage and photosensitivity when ingested.
The common name "hound's-tongue," shared by several species in the genus, refers to the broad, rough-textured leaves reminiscent of a dog's tongue. Flowers within the genus are typically small, tubular, and borne on scorpioid cymes in shades of blue, purple, or red, consistent with the broader Boraginaceae family.
Etymology
The genus name Cynoglossum derives from the Greek kyon (κύων, "dog") and glossa (γλῶσσα, "tongue"), a reference to the broad, rough leaves of the type species that were likened to a dog's tongue. The same image gives rise to the common English name "hound's-tongue."
Distribution
Members of Cynoglossum are native across Eurasia, Africa, New Guinea, and Australia, with the genus most diverse in temperate and montane regions. Cynoglossum officinale, the most widely studied species, is native to Europe, Asia, and Africa and has been introduced — and become invasive — in North America.
Ecology
Several Cynoglossum species produce hooked nutlets (burrs) that adhere to the fur of mammals and the wool of sheep, facilitating long-distance seed dispersal by animals (epizoochory). Cynoglossum officinale contains pyrrolizidine alkaloids, which are toxic to horses, cattle, and other grazing animals, causing hepatotoxicity and photosensitivity upon ingestion; the species is considered a noxious weed in North American pastures for this reason.
