T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Verbena rigida (Rough verbena)

Kingdom:   Plantae
(Unranked):        Angiosperms
(Unranked):        Eudicots
(Unranked):        Asterids
Order:       Lamiales
Family:      Verbenaceae
Genus:      Verbena
Species:     V. rigida
Binomial name: Verbena rigida
Synonyms: Verbena rigida var. lilacina, Verbena rigida var. rigida, Verbena venosa
Common name: Rough Verbena, Stiff Verbena, Sandpaper Verbena, Upright Verbena, Tuberous Vervain, Slender vervain

Verbena rigida is a flowering herbaceous perennial plant and is native to Brazil and Argentina. It will grow to 60 centimetres and it has a spreading habit, with stalkless toothed leaves and bright purple or magenta, scented flowers in summer. There are numerous cultivars.
It can become invasive.

Verbena rigida near the end of flowering

The rough stem.

More photos  http://davesgarden.com/guides/pf/showimage/124600/ 

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/