Tirania purpurea, the sole species in genus Tirania, is a species of climbing plant native to Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

. This genus is related to Forchhammeria and Stixis, but the placement of these three is uncertain. They were placed in Capparaceae

Capparaceae

Capparaceae , commonly known as the Caper family, is a family of plants in order Brassicales. As currently circumscribed, it contains 33 genera and about 700 species...

 until DNA studies showed them to be more closely related to Resedaceae

Resedaceae

Resedaceae is a family of generally herbaceous dicotyledonous plants comprising some 70 species in six genera:*Caylusea*Ochradenus*Oligomeris*Randonia*Reseda*Sesamoides...

 that to Capparaceae. They are sometimes placed in their own family Stixaceae

Stixaceae

Stixaceae is a family in the plant order Brassicales. It is no longer recognised by most taxonomists. The three genera formerly included in Stixaceae — Forchhammeria, Stixis and Tirania — have sometimes been placed instead in the Capparaceae, but it is now clear that they do not belong there...

, but since it is not yet clear whether they are form a clade, they are better left in Brassicales

Brassicales

The Brassicales are an order of flowering plants, belonging to the eurosids II group of dicotyledons under the APG II system. One character common to many members of the order is the production of glucosinolate compounds...

unplaced at family rank.