Stachyacanthus

{{Short description|Genus of plants}}

{{Speciesbox

| image =

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| genus = Stachyacanthus

| parent_authority = Nees (1847)

| species = riedelianus

| authority = Nees (1847)

}}

Stachyacanthus is a monotypic genus of flowering plants belonging to the family Acanthaceae. The only species is Stachyacanthus riedelianus.{{cite web |title=Stachyacanthus Nees {{!}} Plants of the World Online {{!}} Kew Science |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:945-1 |website=Plants of the World Online |access-date=25 September 2021 |language=en}}

The species is found in Mato Grosso state of west-central Brazil.