Helminthotheca echioides, known as bristly (or prickly) oxtongue, is a sprawling annual or biennial herb native to Europe and North Africa.

It is a ruderal plant, found on waste ground and agricultural soils around the world, and in some places it is considered a troublesome weed.

The normal achenes are yellow to orange or brown in colour and have transverse scaly ridges, and a narrowed tip (beak) about as long as the body, to which is affixed a pappus of two rows of white, feathery plumes which enable the seeds to be dispersed by the wind.

Prickly oxtongue has therefore been assigned to two different genera from earliest days, but the combination of Zinn's Helminthotheca and Linnaeus's echioides was not formed until 1973, when the name was coined by the Czech botanist Josef Holub in a paper in the journal Folia Geobotanica & Phytotaxonomica.

Sell & Murrell[3] list four varieties in Britain: The generic name Helminthotheca derives from the Ancient Greek ἕλμινθος (helmins, helminthos), which means "intestinal worm", and θήκη (theca), which is a box or a case (used in anatomy and zoology to describe the sheath around an organ), to make the word "worm-case".

[14][15] The "theca" part of the name might be a reference to the way the capitulum closes up after fruiting, trapping some of the seeds within the "case" of the dead flowerhead.

Helminthotheca echioides is thought to be native to North Africa and the Mediterranean Basin, where it grows in semi-arid conditions that are reproduced in the ruderal habitats associated with agriculture and the disturbed soils created by human activity throughout the world.

[25][26] It has been introduced to North America, where it can now be found from Nova Scotia to British Columbia and California, and it is classified as an invasive weed.

It is considered to act as a therophyte, which completes its life cycle quickly, or a hemicryptophyte, which has a basal rosette to survive unfavourable conditions such as winter or drought.

[1] Typical habitats for it include waste ground, field margins, sea walls, road verges and banks on clay soils or chalk.

The wasp Phanacis caulicola (Hedicke, 1939) has larvae that tunnel chambers inside the stem, leaving no visible sign of their presence until they emerge.

[34][16] The English herbalist Nicholas Culpeper considered "Lang de Boeuf" to be a good cure for melancholy (when steeped in wine), and a general alexipharmic (antidote to unspecified toxins).