''Rumex spinosus'' ( synonym ''Emex spinosa''), commonly known as devil's thorn, spiny dock, or lesser jack, is an annual herbaceous plant of the

Polygonaceae The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus '' Polygonum'', and was first used by Antoine Laurent de Jussieu in 1 ...

. It originates in the warmer parts of the old world, but now has spread with humans to other places. It is common in disturbed areas, especially in sandy soils. It has shown some weedy behaviour in restricted areas within southern Australia.

Description

The lesser jack tends to grow as a sprawling weed. The leaves are plain in shape, resembling spinach. The flowers of different sexes are clustered separately on the same plant. The plant produces many seeds with a hard, prickly casing. These are produced both in clusters along the branches and at the base of the stem. The root is thick and succulent. At the end of the plant's life, the root dries up and pulls the seeds at the base of the stem into the ground. The spiny, durable seeds make the plant a nuisance around human habitats, much like the similarly shaped seeds of ''

Tribulus terrestris ''Tribulus terrestris'' is an annual plant in the caltrop family (Zygophyllaceae) widely distributed around the world. It is adapted to thrive in dry climate locations in which few other plants can survive. It is native to warm temperate and t ...

''.

Taxonomy

''Rumex spinosus'' was first described by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

in 1753. It was transferred to the genus ''Emex'' by

Francisco Campderá Francisco is the Spanish and Portuguese form of the masculine given name '' Franciscus''. Nicknames In Spanish, people with the name Francisco are sometimes nicknamed " Paco". San Francisco de Asís was known as ''Pater Comunitatis'' (father o ...

in 1819. However in 2015, Schuster et al. demoted ''Emex'' to a subgenus of ''Rumex'', restoring the species to Linnaeus's original genus. a move accepted by Plants of the World Online, among other sources.

Uses

Although bitter, the root and leaves can be eaten.

References

spinosus Plants described in 1753 Taxa named by Carl Linnaeus {{Polygonaceae-stub