Tuberaria lignosa is a perennial herb, often woody towards the base. It reaches a height of Template:Convert and branches freely. Its leaves are simple, Template:Convert long and Template:Convert wide. The inflorescence is lax, with each flower Template:Convert in diameter.<ref name="Iberica">Template:Cite book</ref>
Distribution and ecology
The species was first described by Carl Linnaeus in his 1753 work Template:Lang, as "Cistus tuberaria". It was later transferred to the genus Helianthemum, and when Michel Félix Dunal erected Helianthemum sect. Tuberaria in 1824, he designated "Helianthemum tuberaria" as its type species. In 1827, Robert Sweet published a description of "Helianthemum lignosum", but this name was invalid as a junior synonym of H. tuberaria. In 1836, Édouard Spach raised this subgenus to the rank of genus as Tuberaria; because the International Code of Nomenclature for algae, fungi, and plants forbids tautonyms (such as "Tuberaria tuberaria"), the next oldest available name has to be used. In 1922, Gonçalo Sampaio introduced the combination Tuberaria lignosa, which is the name generally used today. Some botanists consider the species part of the genus Xolantha, in which case it is known as Xolantha tuberaria.
- Dunal's publication of Helianthemum sect. Tuberaria in de Candolle's Prodromus